Exercise for knee osteoarthritis pain: Association or causation?

Exercise is universally recommended as a primary strategy for the management of knee osteoarthritis (OA) pain. The recommendations are based on results from more than 100 randomized controlled trials (RCTs) that compare exercise to no-attention control groups. However, due to the inherent difficulties with adequate placebo control, participant blinding and the use of patient-reported outcomes, the existing RCT evidence is imperfect. To better understand the evidence used to support a causal relationship between exercise and knee OA pain relief, we examined the existing evidence through the Bradford Hill considerations for causation. The Bradford Hill considerations, first proposed in 1965 by Sir Austin Bradford Hill, provide a framework for assessment of possible causal relationships. There are 9 considerations by which the evidence is reviewed: Strength of association, Consistency, Specificity, Temporality, Biological Gradient (Dose-Response), Plausibility, Coherence, Experiment, and Analogy. Viewing the evidence from these 9 viewpoints did neither bring forward indisputable evidence for nor against the causal relationship between exercise and improved knee OA pain. Rather, we conclude that the current evidence is not sufficient to support claims about (lack of) causality. With our review, we hope to advance the continued global conversation about how to improve the evidence-based management of patients with knee OA.

"You don't put it down to arthritis": A qualitative study of the first symptoms recalled by individuals with knee osteoarthritis

Objective

As part of the first phase of the OARSI Early-stage Symptomatic Knee Osteoarthritis (EsSKOA) initiative, we explored the first symptoms and experiences recalled by individuals with knee osteoarthritis (OA).

Design

This qualitative study, informed by qualitative description, was a secondary analysis of focus groups (n ​= ​17 groups) and one-on-one interviews (n ​= ​3) conducted in 91 individuals living with knee OA as part of an international study to better understand the OA pain experience. In each focus group or interview, participants were asked to describe their first symptoms of knee OA. We inductively coded these transcripts and conducted thematic analysis.

Results

Mean age of participants was 70 years (range 47-92) and 68 ​% were female. We developed four overarching themes: Insidious and Episodic Onset, Diverse Early Symptoms, Must be Something Else, and Adjustments. Participants described the gradual and intermittent way in which symptoms of knee OA developed over many years; many could not identify a specific starting point. Participants described diverse initial knee symptoms, including activity-exacerbated joint pain, stiffness and crepitus. Most participants dismissed early symptoms or rationalized their presence, employing various strategies to enable continued participation in recreational and daily activities. Few sought medical attention until physical functioning was demonstrably impacted.

Conclusions

The earliest symptoms of knee OA are frequently insidious in onset, episodic and present long before individuals present to health professionals. These results highlight challenges to identifying people with knee OA early and support the development of specific classification criteria for EsSKOA to capture individuals at an early stage.

Diagnostic Accuracy of Candidate Magnetic Resonance Imaging Knee Osteoarthritis Definitions Versus Radiograph in an Acute Anterior Cruciate Ligament Injury Cohort

OBJECTIVE

We tested the diagnostic accuracy of previously proposed magnetic resonance imaging (MRI) osteoarthritis (OA) definitions in a cohort after acute anterior cruciate ligament (ACL) injury.

METHODS

We studied participants with posteroanterior and lateral knee radiographs and MRI 5 years after ACL injury, scored using the Anterior Cruciate Ligament Osteoarthritis Score. Radiographic OA (ROA) was defined using Osteoarthritis Research Society International scoring of osteophytes and joint space narrowing considering medial/lateral tibiofemoral and patellofemoral compartments. We tested three candidate MRI OA definitions that performed well in an older adult cohort. "Multicenter Osteoarthritis Study (MOST) simple" required cartilage score ≥2 (range 0-6) and osteophyte score ≥2 (0-7); "MOST optional" included cartilage score ≥2, osteophyte score ≥2, and either bone marrow lesions (BMLs) ≥1 (0-3) or synovitis ≥2 (0-3). The third, a Delphi panel definition, included nonzero scores for cartilage, osteophyte, BMLs, meniscus, and other structures. We calculated sensitivity and specificity with 95% confidence intervals (95% CIs) for each MRI definition versus ROA.

RESULTS

We included 113 participants (mean age 26 years, 26% female). At 5 years, 29 participants (26%) had ROA. "MOST simple" had a sensitivity of 52% (95% CI 33%-71%), and specificity of 76% (95% CI 66%-85%). Sensitivity and specificities for "MOST optional" were 28% (95% CI 29%-67%) and 83% (95% CI 74%-91%), respectively. The Delphi panel definition had a sensitivity of 48% (95% CI 29%-67%) and specificity of 77% (95% CI 67%-86%).

CONCLUSION

Simple MRI-based OA definitions requiring at least cartilage damage and an osteophyte have low sensitivity and high specificity in young persons after knee injury.

Genetic Influence on Osteoarthritis Versus Other Rheumatic Diseases

OBJECTIVE

We aimed to compare the genetic contribution to osteoarthritis (OA) versus other rheumatic/musculoskeletal diseases (RMDs) in the same population and to explore the role for any shared genetics between OA and other RMDs.

METHODS

In 59,970 Swedish twins aged 35 years or older, we estimated the heritability (the variance explained by genetic factors) of OA in peripheral joints, back and neck pain, shoulder pain (adhesive capsulitis, impingement syndrome, etc), rheumatoid arthritis, spondyloarthritis (SpA) and psoriatic arthritis, myalgia, and osteoporosis diagnosed in specialist and inpatient care. We also studied how much covariance between OA and each of the RMDs could be explained by genetics by studying phenotypic correlations in bivariate classical twin models.

RESULTS

Any-site OA and hip OA (50% and 64%) were among the most heritable RMDs (as compared with 23% for fibromyalgia [lowest] and 63% for SpA [highest]). The highest phenotypic correlations were between OA (any joint site) and shoulder pain in the same individual (r = 0.33, 95% confidence interval 0.31-0.35), of which 70% (95% confidence interval 52-88) could be explained by shared genetics. The phenotypic correlation between OA and back/neck pain was r = 0.25, with 25% to 75% explained by genetics. Phenotypic correlations between OA and each of the other RMDs were lower (r ~ 0.1 to r ~ 0.2), with inconclusive sources of variation.

CONCLUSION

OA has relatively large heritability as compared with other RMDs. The coexistence of OA and shoulder pain, as well as back pain, was common and could often be explained by genetic factors. Findings imply similar etiologies of OA and several pain conditions.

Proteomic profiling of human menisci from mild joint degeneration and end-stage osteoarthritis versus healthy controls

Objective

To gain new insight into the molecular changes of the meniscus by comparing the proteome profiles of healthy controls with mild degeneration and end-stage osteoarthritis (OA).

Method

We obtained tissue plugs from lateral and medial menisci of 37 individuals (central part of the posterior horn) classified as healthy (n ​= ​12), mild signs of joint damage (n ​= ​13) and end-stage OA (n ​= ​12). The protein profile was analysed by nano-liquid chromatography-mass spectrometry using data-independent acquisition and quantified by Spectronaut. Linear-mixed effects modelling was applied to extract the between-group comparisons.

Results

A similar protein profile was observed for the mild group as compared to healthy controls while the most different group was end-stage OA mainly for the medial compartment. When a pattern of gradual change in protein levels from healthy to end-stage OA was required, a 42-proteins panel was identified, suggesting a potential role in OA development. The levels of QSOX1 were lower and G6PD higher in the mild group following the proposed protein abundance pattern. Qualitative protein changes suggest lower levels of CYTL1 as a potential biomarker of early joint degradation.

Conclusion

For future targeted proteomic approaches, we propose a candidate panel of 42 proteins based on gradually altered meniscal posterior horn protein abundance patterns associated with joint degradation.

A human meniscus explant model for studying early events in osteoarthritis development by proteomics

Degenerative meniscus lesions have been associated with both osteoarthritis etiology and its progression. We, therefore, sought to establish a human meniscus ex vivo model to study the meniscal response to cytokine treatment using a proteomics approach. Lateral menisci were obtained from five knee-healthy donors. The meniscal body was cut into vertical slices and further divided into an inner (avascular) and outer region. Explants were either left untreated (controls) or stimulated with cytokines. Medium changes were conducted every 3 days up to Day 21 and liquid chromatography-mass spectrometry was performed at all the time points for the identification and quantification of proteins. Mixed-effect linear regression models were used for statistical analysis to estimate the effect of treatments versus control on protein abundance. Treatment by IL1ß increased release of cytokines such as interleukins, chemokines, and matrix metalloproteinases but a limited catabolic effect in healthy human menisci explants. Further, we observed an increased release of matrix proteins (collagens, integrins, prolargin, tenascin) in response to oncostatin M (OSM) + tumor necrosis factor (TNF) and TNF+interleukin-6 (IL6) + sIL6R treatments, and analysis of semitryptic peptides provided additional evidence of increased catabolic effects in response to these treatments. The induced activation of catabolic processes may play a role in osteoarthritis development.

Use of non-surgical treatments on the journey to knee replacement in patients with knee osteoarthritis: a 10-year population-based case-control study

AIM

To investigate temporal trends in primary care visits, physiotherapy visits, dispensed non-steroidal anti-inflammatory drugs (NSAIDs) and opioids in knee osteoarthritis (OA) patients who have and have not undergone knee replacement.

METHODS

We analysed 5665 OA patients from the Skåne Healthcare Register, Sweden, who underwent knee replacement between 2015 and 2019. Controls were OA patients without knee replacement, matched 1:1 by sex, age, time and healthcare level of initial OA diagnosis, and assigned a pseudo-index date corresponding to their case's knee replacement date. Annual prevalence and prevalence ratio of primary care and physiotherapy visits, dispensed NSAIDs and opioids (all for any cause) in the 10 years before knee replacement were estimated using Poisson regression.

RESULTS

The annual prevalence of all-cause primary care visits, physiotherapy visits and opioid use was similar between cases and controls until 3 years before the index date when it started to increase among the cases. The year before the index date, the prevalence ratio (cases vs controls) for physiotherapy use was 1.8 (95% CI 1.7, 1.8), while for opioid use 1.6 (1.5, 1.7). NSAID use was consistently higher among cases, even 10 years before the index date when the prevalence ratio versus controls was 1.3 (1.2, 1.3), increasing to 1.8 (1.7, 1.9) in the year preceding the index date.

CONCLUSIONS

Management of OA patients who have and have not undergone knee replacement appears largely similar except for higher use of NSAIDs in knee replacement cases. Symptomatic treatments start to increase a few years before the surgery in knee replacement cases.

Identifying Non-Steroidal Anti-Inflammatory Drug (NSAID) Users Among People with Osteoarthritis Through Administrative and Clinician-Reported Data - A Validation Study of 116,162 Patients

Purpose

(i) To report the prevalence of participants to a first-line intervention for OA in Sweden using over-the-counter (OTC) and/or prescribed NSAIDs; (ii) To estimate the accuracy of dispensed prescriptions of NSAIDs recorded in a Swedish health-care register to capture the use of NSAID considering clinician-report as reference standard.

Methods

Register-based study. We used data from OA individuals who participated in the Swedish first-line intervention recorded in the Swedish Osteoarthritis Register (SOAR). SOAR includes clinician-reported use of NSAIDs in the three months preceding the intervention. We used the Prescribed Drug Register to retrieve data on NSAID prescriptions dispensed in the same period. We estimated the prevalence of OTC users (individuals with clinicians-reported use of NSAID but no prescription dispensed), prescription users (individuals with clinicians-reported use of NSAID and a prescription dispensed) and non-users (neither of the previous). We calculated sensitivity, specificity, positive predictive value, and negative predictive value of dispensed prescriptions of NSAIDs vs clinician-report.

Results

We included 116,162 individuals (mean age [Standard Deviation]: 66 [9.6] years, 79% women, 77% knee OA). Overall, 24.7% (95% Confidence Intervals [CI] 24.5%; 25.0%) used OTC NSAIDs only, 18.2% (18.0%; 18.5%) used prescribed NSAIDs, 6.6% (6-4%; 6.7%) reported not using NSAIDs while having an NSAID prescription dispensed. Of the 49,913 individuals with clinician-reported use of NSAIDs, 21,190 had a prescription dispensed (sensitivity: 42.5% [95% CI 42.0%, 42.9%]; positive predictive value: 73.5% [73.0%, 74.0%]). Of the 66,249 individuals reporting not using NSAIDs, 58,617 did not have a prescription dispensed (specificity: 88.5% [88.2%, 88.7%]; negative predictive value: 67.1% [66.8%, 67.4%]).

Conclusion

Overall, 24.7% of participants in a first-line intervention for OA used OTC NSAIDs only while 18.2% used prescribed NSAIDs. Dispensed prescriptions of NSAIDs have high specificity but low sensitivity and can correctly identify about 70% of both the non-users and users in this population.

Identification and quantification of degradome components in human synovial fluid reveals an increased proteolytic activity in knee osteoarthritis patients vs controls

Synovial fluid (SF) may contain cleavage products of proteolytic activities. Our aim was to characterize the degradome through analysis of proteolytic activity and differential abundance of these components in a peptidomic analysis of SF in knee osteoarthritis (OA) patients versus controls (n = 23). SF samples from end-stage knee osteoarthritis patients undergoing total knee replacement surgery and controls, that is, deceased donors without known knee disease were previously run using liquid chromatography mass spectrometry (LC-MS). This data was used to perform new database searches generating results for non-tryptic and semi-tryptic peptides for studies of degradomics in OA. We used linear mixed models to estimate differences in peptide-level expression between the two groups. Known proteolytic events (from the MEROPS peptidase database) were mapped to the dataset, allowing the identification of potential proteases and which substrates they cleave. We also developed a peptide-centric R tool, proteasy, which facilitates analyses that involve retrieval and mapping of proteolytic events. We identified 429 differentially abundant peptides. We found that the increased abundance of cleaved APOA1 peptides is likely a consequence of enzymatic degradation by metalloproteinases and chymase. We identified metalloproteinase, chymase, and cathepsins as the main proteolytic actors. The analysis indicated increased activity of these proteases irrespective of their abundance.

Prevalence of long COVID complaints in persons with and without COVID-19

We studied the prevalence and patterns of typical long COVID complaints in ~ 2.3 million individuals aged 18-70 years with and without confirmed COVID-19 in a Nation-wide population-based prospective cohort study in Norway. Our main outcome measures were the period prevalence of single-occurring or different combinations of complaints based on medical records: (1) Pulmonary (dyspnea and/or cough), (2) Neurological (concentration problems, memory loss), and/or (3) General complaints (fatigue). In persons testing positive (n = 75 979), 64 (95% confidence interval: 54 to 73) and 122 (111 to 113) more persons per 10 000 persons had pulmonary complaints 5-6 months after the test compared to 10 000 persons testing negative (n = 1 167 582) or untested (n = 1 084 578), respectively. The corresponding difference in prevalence of general complaints (fatigue) was 181 (168 to 195) and 224 (211 to 238) per 10 000, and of neurological complaints 5 (2 to 8) and 9 (6-13) per 10 000. Overlap between complaints was rare. Long COVID complaints were only slightly more prevalent in persons with than without confirmed COVID-19. Still, long COVID may pose a substantial burden to healthcare systems in the future given the lasting high incidence of symptomatic COVID-19 in both vaccinated and unvaccinated individuals.

3D analysis and grading of calcifications from ex vivo human meniscus

OBJECTIVE

Meniscal calcifications are associated with the pathogenesis of knee osteoarthritis (OA). We propose a micro-computed tomography (μCT) based 3D analysis of meniscal calcifications ex vivo, including a new grading system.

METHOD

Human medial and lateral menisci were obtained from 10 patients having total knee replacement for medial compartment OA and 10 deceased donors without knee OA (healthy references). The samples were fixed; one subsection was imaged with μCT, and the adjacent tissue was processed for histological evaluation. Calcifications were examined from the reconstructed 3D μCT images, and a new grading system was developed. To validate the grading system, meniscal calcification volumes (CV_M) were quantitatively analyzed and compared between the calcification grades. Furthermore, we estimated the relationship between histopathological degeneration and the calcification severity.

RESULTS

3D μCT images depict calcifications in every sample, including diminutive calcifications that are not visible in histology. In the new grading system, starting from grade 2, each grade results in a CV_M that is 20.3 times higher (95% CI 13.3-30.5) than in the previous grade. However, there was no apparent difference in CV_M between grades 1 and 2. The calcification grades appear to increase with the increasing histopathological degeneration, although histopathological degeneration is also observed with small calcification grades.

CONCLUSIONS

3D μCT grading of meniscal calcifications is feasible. Interestingly, it seems that there are two patterns of degeneration in the menisci of our sample set: 1) with diminutive calcifications (calcification grades 1-2), and 2) with large to widespread calcifications (calcification grades 3-5).

Evidence of ACL healing on MRI following ACL rupture treated with rehabilitation alone may be associated with better patient-reported outcomes: a secondary analysis from the KANON trial

OBJECTIVES

Evaluate the natural course of anterior cruciate ligament (ACL) healing on MRI within 5 years of acute ACL rupture and compare 2-year and 5-year outcomes based on healing status and treatment group.

METHODS

Secondary analysis of 120 Knee Anterior Cruciate Ligament Nonsurgical vs Surgical Treatment (KANON) trial participants randomised to rehabilitation and optional delayed ACL reconstruction (ACLR) or early ACLR and rehabilitation. ACL continuity on MRI (Anterior Cruciate Ligament OsteoArthritis Score 0-2) was considered evidence of ACL healing. Outcomes included Knee Injury and Osteoarthritis Outcome Score (KOOS), KOOS patient acceptable symptomatic state (PASS) and treatment failure criteria. Linear mixed models were used to estimate adjusted mean differences (95% CIs) in patient-reported sport and recreational function (KOOS-Sport/Rec) and quality of life (KOOS-QOL) at 2 and 5 years, between participants with MRI evidence of ACL healing and those who had (1) no evidence of ACL healing, (2) delayed ACLR or (3) early ACLR.

RESULTS

MRI evidence of ACL healing at 2-year follow-up was observed in 16 of 54 (30%, 95% CI 19 to 43%) participants randomised to optional delayed ACLR. Excluding participants who had delayed ACLR, 16 of 30 (53%, 36-70%) participants managed with rehabilitation-alone displayed MRI evidence of ACL healing. Two-year outcomes were better in the healed ACL group (n=16) compared with the non-healed (n=14) (mean difference (95% CI) KOOS-Sport/Rec: 25.1 (8.6-41.5); KOOS-QOL: 27.5 (13.2-41.8)), delayed ACLR (n=24) (KOOS-Sport/Rec: 24.9 (10.2-39.6); KOOS-QOL: 18.1 (5.4-30.8)) and early ACLR (n=62) (KOOS-Sport/Rec: 17.4 (4.1-30.7); KOOS-QOL: 11.4 (0.0-22.9)) groups. Five-year KOOS-QOL was better in the healed versus non-healed group (25.3 (9.4-41.2)). Of participants with MRI evidence of ACL healing, 63-94% met the PASS criteria for each KOOS subscale, compared with 29-61% in the non-healed or reconstructed groups.

CONCLUSIONS

MRI appearance of ACL healing after ACL rupture occurred in one in three adults randomised to initial rehabilitation and one in two who did not cross-over to delayed ACLR and was associated with favourable outcomes. The potential for spontaneous healing of the ACL to facilitate better clinical outcomes may be greater than previously considered.

TRIAL REGISTRATION NUMBER

ISRCTN84752559.

Associations of human femoral condyle cartilage structure and composition with viscoelastic and constituent-specific material properties at different stages of osteoarthritis

The relationships between structure and function in human knee femoral cartilage are not well-known at different stages of osteoarthritis. Thus, our aim was to characterize the depth-dependent composition and structure (proteoglycan content, collagen network organization and collagen content) of normal and osteoarthritic human femoral condyle cartilage (n = 47) and relate them to their viscoelastic and constituent-specific mechanical properties that are obtained through dynamic sinusoidal testing and fibril-reinforced poroelastic material modeling of stress-relaxation testing, respectively. We characterized the proteoglycan content using digital densitometry, collagen network organization (orientation angle and anisotropy) using polarized light microscopy and collagen content using Fourier transform infrared spectroscopy. In the superficial cartilage (0-10 % of thickness), the collagen network disorganization and proteoglycan loss were associated with the smaller initial fibril network modulus - a parameter representing the pretension of the collagen network. Furthermore, the proteoglycan loss was associated with the greater strain-dependent fibril network modulus - a measure of nonlinear mechanical behavior. The proteoglycan loss was also associated with greater cartilage viscosity at a low loading frequency (0.005 Hz), while the collagen network disorganization was associated with greater cartilage viscosity at a high loading frequency (1 Hz). Our results suggest that proteoglycan loss and collagen network disorganization reduce the pretension of the collagen network while proteoglycan degradation also increases the nonlinear mechanical behavior of the collagen network. Further, the results also highlight that proteoglycan loss and collagen disorganization increase the viscosity of femoral cartilage, but their contribution to increased viscosity occurs in completely different loading frequencies.

Post-covid medical complaints following infection with SARS-CoV-2 Omicron vs Delta variants

The SARS-CoV-2 Omicron (B.1.1.529) variant has been associated with less severe acute disease, however, concerns remain as to whether long-term complaints persist to a similar extent as for earlier variants. Studying 1 323 145 persons aged 18-70 years living in Norway with and without SARS-CoV-2 infection in a prospective cohort study, we found that individuals infected with Omicron had a similar risk of post-covid complaints (fatigue, cough, heart palpitations, shortness of breath and anxiety/depression) as individuals infected with Delta (B.1.617.2), from 14 to up to 126 days after testing positive, both in the acute (14 to 29 days), sub-acute (30 to 89 days) and chronic post-covid (≥90 days) phases. However, at ≥90 days after testing positive, individuals infected with Omicron had a lower risk of having any complaint (43 (95%CI = 14 to 72) fewer per 10,000), as well as a lower risk of musculoskeletal pain (23 (95%CI = 2-43) fewer per 10,000) than individuals infected with Delta. Our findings suggest that the acute and sub-acute burden of post-covid complaints on health services is similar for Omicron and Delta. The chronic burden may be lower for Omicron vs Delta when considering musculoskeletal pain, but not when considering other typical post-covid complaints.

The Road to Total Knee Replacement - Utilisation of Knee Surgeries up to 10 Years Before TKR in England and Sweden

OBJECTIVES

To compare the prevalence and timing of knee surgery (including meniscal, ligamentous, synovial and osteotomy) in the ten years prior to primary total knee replacement (TKR) between England and Sweden.

METHODS

This was a population-based, case-control study within England and southern Sweden using electronic healthcare databases. Cases underwent primary TKR between 2015 and 2019. Risk-set sampling identified general population controls matched 1:1 by age, sex and practice/municipality. The annual prevalence and prevalence ratio (PR) of having at least one recorded surgery in each of the 10 years preceding TKR was estimated using Poisson regressions.

RESULTS

We included 6,308 and 47,010 TKR cases in Sweden and England, respectively. Meniscal surgeries were the most frequent procedure prior to TKR in both countries - prevalence was higher in England across all time points. The prevalence of meniscal surgery increased in both countries in the years approaching TKR, reaching 33.2 (95% confidence interval 31.6-34.9) per 1,000 persons in England, and 9.83 (7.66, 12.61) in Sweden. In England, we observed a decrease from 2014 to 2018 in the utilisation of this procedure in the four years preceding a TKR. The prevalence of all analysed surgeries was consistently lower in controls.

CONCLUSIONS

There are comparable trends in the use of knee surgery in the years preceding TKR across England and Sweden. Of note, meniscal surgeries remain common, even within the year prior to TKR, highlighting that these patients may experience low-value care. Careful consideration of knee surgery in those with late-stage disease is required.

Mineral Crystal Thickness in Calcified Cartilage and Subchondral Bone in Healthy and Osteoarthritic Human Knees

Osteoarthritis (OA) is the most common joint disease, where articular cartilage degradation is often accompanied with sclerosis of the subchondral bone. However, the association between OA and tissue mineralization at the nanostructural level is currently not understood. In particular, it is technically challenging to study calcified cartilage, where relevant but poorly understood pathological processes such as tidemark multiplication and advancement occur. Here, we used state-of-the-art microfocus small-angle X-ray scattering with a 5-μm spatial resolution to determine the size and organization of the mineral crystals at the nanostructural level in human subchondral bone and calcified cartilage. Specimens with a wide spectrum of OA severities were acquired from both medial and lateral compartments of medial compartment knee OA patients (n = 15) and cadaver knees (n = 10). Opposing the common notion, we found that calcified cartilage has thicker and more mutually aligned mineral crystals than adjoining bone. In addition, we, for the first time, identified a well-defined layer of calcified cartilage associated with pathological tidemark multiplication, containing 0.32 nm thicker crystals compared to the rest of calcified cartilage. Finally, we found 0.2 nm thicker mineral crystals in both tissues of the lateral compartment in OA compared with healthy knees, indicating a loading-related disease process because the lateral compartment is typically less loaded in medial compartment knee OA. In summary, we report novel changes in mineral crystal thickness during OA. Our data suggest that unloading in the knee might be involved with the growth of mineral crystals, which is especially evident in the calcified cartilage. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

A Drosophila Su(H) model of Adams-Oliver Syndrome reveals cofactor titration as a mechanism underlying developmental defects

Notch signaling is a conserved pathway that converts extracellular receptor-ligand interactions into changes in gene expression via a single transcription factor (CBF1/RBPJ in mammals; Su(H) in Drosophila). In humans, RBPJ variants have been linked to Adams-Oliver syndrome (AOS), a rare autosomal dominant disorder characterized by scalp, cranium, and limb defects. Here, we found that a previously described Drosophila Su(H) allele encodes a missense mutation that alters an analogous residue found in an AOS-associated RBPJ variant. Importantly, genetic studies support a model that heterozygous Drosophila with the AOS-like Su(H) allele behave in an opposing manner to heterozygous flies with a Su(H) null allele, due to a dominant activity of sequestering either the Notch co-activator or the antagonistic Hairless co-repressor. Consistent with this model, AOS-like Su(H) and Rbpj variants have decreased DNA binding activity compared to wild type proteins, but these variants do not significantly alter protein binding to the Notch co-activator or the fly and mammalian co-repressors, respectively. Taken together, these data suggest a cofactor sequestration mechanism underlies AOS phenotypes associated with RBPJ variants, whereby the AOS-associated RBPJ allele encodes a protein with compromised DNA binding activity that retains cofactor binding, resulting in Notch target gene dysregulation.

Adams-Oliver Syndrome (AOS) is a rare disease defined by missing skin/skull tissue, limb malformations, and cardiovascular abnormalities. Human genetic studies have revealed that ~40% of AOS patients inherit dominant mutations within specific genes in the Notch signaling pathway. Notch signaling is a highly conserved cell-to-cell communication pathway found in all metazoans and plays crucial roles during embryogenesis and tissue homeostasis in organisms from Drosophila (fruit-flies) to mammals. The Notch receptor converts cell-to-cell interactions into a Notch signal that enters the nucleus and activates target genes by binding to a highly conserved transcription factor. Here, we took advantage of the unexpected finding that a previously described dominant allele in the Drosophila Notch pathway transcription factor contains a missense variant in an analogous residue found in a family with AOS. Using this novel animal model of AOS along with biochemical DNA binding, protein-protein interaction, and transcriptional reporter assays, we found that this transcription factor variant selectively compromises DNA binding but not binding to the Notch signal nor binding to other proteins in the Notch pathway. Taken together with prior human genetic studies, these data suggest AOS phenotypes associated with variants in the Notch pathway transcription factor are caused by a dominant mechanism that sequesters the Notch signal, leading to Notch target gene dysregulation.

Trends of Dispensed Opioids in Catalonia, Spain, 2007-19: A Population-Based Cohort Study of Over 5 Million Individuals

Objective: To characterize the trend of opioid use (number of users, dispensations and oral morphine milligram equivalents) in Catalonia (Spain).

Design, setting, and participants: This population-based cohort study included all individuals aged 18 years or older, registered in the Information System for Research in Primary Care (SIDIAP), which covers >75% of the population in Catalonia, Spain, from 1 January 2007, to 31 December 2019.

Main exposure and outcomes: The exposures were all commercialized opioids and their combinations (ATC-codes): codeine, tramadol, oxycodone, tapentadol, fentanyl, morphine, and other opioids (dihydrocodeine, hydromorphone, dextropropoxyphene, buprenorphine, pethidine, pentazocine). The main outcomes were the annual figures per 1,000 individuals of 1) opioid users, 2) dispensations, and 3) oral morphine milligram equivalents (MME). Results were stratified separately by opioid types, age (5-year age groups), sex (male or female), living area (rural or urban), and socioeconomic status (from least, U1, to most deprived, U5). The overall trends were quantified using the percentage change (PC) between 2007 and 2019.

Results: Among 4,656,197 and 4,798,114 residents from 2007 to 2019, the number of opioid users, dispensations and morphine milligram equivalents per 1,000 individuals increased 12% (percentage change: 95% confidence interval (CI) 11.9–12.3%), 105% (95% confidence interval 83%–126%) and 339% (95% CI 289%–390%) respectively. Tramadol represented the majority of opioid use in 2019 (61, 59, and 54% of opioid users, dispensations, and total MME, respectively). Individuals aged 80 years or over reported the sharpest increase regarding opioid users (PC: 162%), dispensations (PC: 424%), and MME (PC: 830%). Strong opioids were increasingly prescribed for non-cancer pains over the years.

Conclusion: Despite the modest increase of opioid users, opioid dispensations and MME increased substantially, particularly in the older population. In addition, strong opioids were incrementally indicated for non-cancer pains over the years. These findings suggest a transition of opioid prescriptions from intermittent to chronic and weak to strong and call for more rigorous opioid stewardship.

OP0228 USE OF NON-STEROIDAL ANTI-INFLAMMATORY DRUGS AND RISK OF COMORBIDITIES IN PEOPLE WITH AND WITHOUT OSTEOARTHRITIS - A UK PRIMARY CARE DATABASE COHORT STUDY

Background

People with osteoarthritis (OA) are at higher risk of developing a wide array of comorbidities. Whether the use of non-steroidal anti-inflammatory drugs (NSAIDs) contributes to the increased risk of some incident comorbidities remains unknown.

Objectives

To examine the contribution of NSAIDs in the development of a wide range of comorbidities in people with and without OA.

Methods

This observational cohort study used the UK primary care Clinical Practice Research Datalink (CPRD) GOLD containing data on 20+ million people covering 937 practices. We identified 259,000 people with incident OA and 259,000 age (±2 years), sex, and practice matched controls at 1:1 ratio. Controls were assigned the same index date (the date of first diagnosis of OA) as cases for the start of follow-up. Both cases and controls were further divided into two groups according to NSAID prescriptions at any time after the index date. This allowed us to examine both the main effect of each exposure and interaction between OA and NSAID exposure after the index date. People with an NSAID prescription before the index date were excluded from the study. NSAID exposure was defined as at least two prescriptions within 90 days. Exposure status of each participant was assessed every six months as yes/no until the end of the study/outcome of interests/death/last data available, whichever came first. Comorbidities were grouped into 9 categories as cancer, cardiovascular disease (CVD), endocrine, psychological, renal, gastrointestinal (GI), genitourinary, hepatic, and neurological conditions. Propensity scores for the prescription of NSAIDs were calculated using a logistic regression model including age, sex, body mass index (BMI), musculoskeletal and pain related conditions covariates. The propensity score adjusted time varying exposure analysis was undertaken using a multivariate COX model and hazard ratio (HR) and 95% confidence intervals were calculated. Proportional hazard assumption was tested using Schoenfeld test. Smoking, alcohol, ever prescription of proton pump inhibitors (PPIs) and other comorbidities were included in the adjusted model. The additional contribution of NSAIDs and OA towards the incident comorbidity was estimated using addictive interaction methods. We also investigated the individual risk across non-selective, and COX-2 selective NSAIDs.

Results

The mean age was 59.4±12.8 years in people with OA and 60.2±12.8 years for controls with 57.7% being female. Nearly two thirds of people with OA were prescribed NSAIDs as defined, compared to one third in the control population. People with OA and exposed to NSAIDs had highest risk of developing psychological (1.51; 1.43,1.60), CVD (1.38; 1.33,1.43), cancer (1.34; 1.25,1.44), GI (1.25; 1.16,1.34) and renal (1.17; 1.11,1.24) comorbidities after adjusting for all the covariates and PPI drugs, compared to the non-OA and non-NSAID group. (Figure 1) Interaction between OA and NSAID was significant for cancer, GI, renal, hepatic, and neurological outcomes. Within people with OA, non-selective NSAIDs increased the risk of CVD (1.25; 1.20,1.30), cancer (1.11; 1.04,1.19), endocrine (1.15; 1.10,1.19), renal (1.19; 1.13,1.26) and psychological (1.21; 1.15,1.28) comorbidities, whereas COX-2 selective NSAIDs increased risk of incident CVD (1.34; 1.25,1.44), endocrine (1.13; 1.04,1.21), renal (1.25; 1.14,1.37), and psychological (1.21; 1.09,1.34) comorbidities.

Figure 1.

Hazard ratio of developing different comorbidities (reference group: no OA and no NSAIDs) OA- Osteoarthritis; NSAIDS- Non-steroidal anti-inflammatory drugs.

Conclusion

Use of NSAIDs among people with OA is associated with increased risk of a wide variety of comorbidities. Non-selective and COX-2 selective NSAIDs are both associated with increased risk of cardiovascular, renal, and psychological comorbidities.

Acknowledgements

We thank the Patient Research Participants (PRP) members Jenny Cockshull, Stevie Vanhegan, and Irene Pitsillidou for their involvement since the beginning of the project. We would like to thank the FOREUM for financially supporting the research.

Disclosure of Interests

Subhashisa Swain: None declared, Anne Kamps: None declared, Jos Runhaar: None declared, Andrea Dell’Isola: None declared, Aleksandra Turkiewicz: None declared, Danielle E Robinson: None declared, Victoria Y Strauss: None declared, Christian Mallen: None declared, Chang-Fu Kuo: None declared, Carol Coupland: None declared, Michael Doherty Consultant of: Consultant of: Advisory borads on gout for Grunenthal and Mallinckrodt, Grant/research support from: Michael Doherty Grant/research support from: AstraZeneca funded the Nottingham Sons of Gout study, Aliya Sarmanova: None declared, Daniel Prieto-Alhambra Speakers bureau: paid speaker services from Amgen and UCB Biopharma., Consultant of: His department has received advisory or consultancy fees from Amgen, Astellas, AstraZeneca, Johnson, and Johnson, and UCB Biopharma, Grant/research support from: Prof. Prieto-Alhambra’s research group has received grant support from Amgen, Chesi-Taylor, Novartis, and UCB Biopharma., Martin Englund: None declared, S.M.A. Bierma-Zeinstra: None declared, Weiya Zhang Speakers bureau: Speakers bureau: Bioiberica as an invited speaker for EULAR 2016 satellite symposium, Consultant of: Consultant of: Grunenthal for advice on gout management,

POS1132 PATTERNS OF JOINT SURGERY IN THE TEN YEARS PRIOR TO PRIMARY KNEE REPLACEMENT IN ENGLAND AND SWEDEN – A POPULATION-BASED CASE-CONTROL STUDY

Background

Primary knee replacement (KR) is an effective intervention for end-stage knee osteoarthritis (OA). However, there are no definitive recommendations for the timing at which patients should receive this surgery, potentially resulting in differences in referral patterns depending on geographical area or the clinicians‘ preferences.

Objectives

To investigate the prevalence of meniscus, knee ligament and knee synovial surgeries as well as knee osteotomy and hip replacement (HR) across the ten years preceding a KR in cases and controls in England and Sweden.

Methods

This was a multi-national, population-based, case-control study within England and Sweden. Cases underwent primary TKR and controls, matched using risk-set sampling by age, sex and practice/region, did not. Electronic healthcare databases were used; the Clinical Practice Research Datalink (CPRD) in England, and the Health Register of Skåne (Sweden’s southernmost region) in Sweden.

ICD-10 codes and KVÅ codes in Sweden and Medcodes (SNOMED CT (UK edition) and Read codes) in England were used to identify subjects aged ≥45 years who underwent primary KR between 1st January 2015 and 31st December 2019. Eligible cases had to be registered for ≥10 years prior to the primary KR (index date), and have no record of prior KR in that period.

Office of Population Censuses and Surveys (OPCS) codes in England and ICD-10 codes in Sweden were used to identify selected orthopaedic surgeries.

Meniscal (e.g. excision, resection, repair) and ligament surgery (e.g. ligament reconstruction, replacement, suture) were included, as well as osteotomy (e.g. angle, rotational or displacement osteotomy of the knee or lower leg). Hip replacement (HR) (any primary HR) was also included, to evaluate the rate at which patients undergoing KR also undergo further major arthroplasty in the years preceding this – The annual prevalence of having at least one recorded surgery for each type in each of the 10 years preceding KR was estimated using Poisson regression models and expressed per 1,000 people.

Results

We identified 6,337 and 47,010 subjects who underwent a knee replacement between 2015 and 2019 in southern Sweden and England, respectively (Table 1). Overall, the prevalence of all analysed surgeries was consistently lower in the controls with minimal trends detectable throughout follow-up in both England and Sweden (Figure 1).

Table 1.

demographic

SwedenEnglandCases(n=6,337)Controls(n=6,337)Cases(n=47,010)Controls(n=47,010)Age, mean (SD)69.0 (8.9)68.9 (9.1)69.6 (9.6)69.6 (9.6)Female Sex, n (%)3,585 (56.6%)3,585 (56.6%)26,154 (55.6%)26,154 (55.6%)Surgeries, n Hip replacement5623243,9331,889 Meniscus384448,659833 Ligaments1659011 Synovial1641536930 Osteotomy9831075

On the other hand, an increasing trend among the cases, signifying a higher prevalence of surgeries when nearing KR, was observed for HR and meniscal surgeries in both nations. The prevalence of HR was similar in England and southern Sweden at all-time points showing an increase most noticeable in the 3 years before KR. The prevalence of meniscus surgery in England was higher than the one observed in Sweden throughout the follow-up. Prevalence in England increased most noticeably in the four years prior to KR reaching 33.2 (95%CI 31.6, 34.9) surgeries per 1,000 people in the year preceding KR. In Sweden, the prevalence of meniscus surgery remained between four and eight surgeries per 1,000 people until the last year prior to KR when the prevalence increased to 13.8 (95%CI 11.9, 16.2) surgeries per 1,000 people.

Conclusion

HR and meniscal surgeries are common procedures that a person is likely to have experienced in the ten years prior to a KR. Comparing England and southern Sweden, we noticed similar prevalence and trends for what concerns HR suggesting similar practice in the two healthcare systems. Meniscus surgeries were more frequently utilised in England. Nevertheless, in both countries, a marked increase in the prevalence of this surgery was observed in the last years prior to the KR.

Disclosure of Interests

None declared

Opioid use prior to total knee replacement: comparative analysis of trends in England and Sweden

OBJECTIVES

To describe and compare trends in the frequency of opioid prescribing/dispensing in English and Swedish patients with osteoarthritis prior to total knee replacement (TKR).

METHODS

49,043 patients from an English national database (Clinical Practice Research Datalink) and 5,955 patients from the Swedish Skåne Healthcare register undergoing TKR between 2015 and 2019 were included, alongside 1:1 age-, sex-, and practice (residential area) matched controls. Annual prevalence and prevalence rates ratio (PRR) of opioid prescribing/dispensing (any, by strength) in the 10 years prior to TKR (or matched index date for controls) were estimated using Poisson regression.

RESULTS

In England and Sweden, the prevalence of patients with osteoarthritis receiving any opioid prior to TKR increased towards the date of surgery from 24% to 44% in England and from 16% to 33% in Sweden. Prescribing in controls was stable, resulting in an increasing PRR (1.6-2.7) between 10 and 1 years prior to index date in both countries. No relevant cohort or period effect was observed in either country. Prevalence of opioid prescribing was higher in English cases and controls; weaker opioids were more commonly prescribed in England, stronger opioids in Sweden.

CONCLUSIONS

Temporal prevalence patterns of opioid prescribing between cases and controls are similar in England and Sweden. Opioids are still commonly used in TKR cases in both countries highlighting the lack of valid alternatives for OA pain management.

POS1124 EVALUATION OF COMORBIDITY PATTERNS AND IDENTIFICATION OF SUB-GROUPS IN PATIENTS DIAGNOSED WITH HIP OSTEOARTHRITIS IN 94,720 PATIENTS FROM SPAIN

Background

Osteoarthritis (OA) patients are more likely to have other comorbidities (Swain, Sarmanova et al. 2020). Improving the understanding of comorbidity profiles of OA patients may lead to improvement in their clinical care.

Objectives

To identify sub-groups in patients diagnosed with hip OA using patterns of comorbidity.

Methods

Routinely-collected data of individuals ≥18 years with an incident diagnosis of hip OA (baseline/time of diagnosis), with at least 1 year of follow-up in SIDIAP (Information System for Research in Primary Care, a primary case database from Spain) were collected from January 1st 2006 to June 31st 2020. Those with soft-tissue disorders or other bone/cartilage diseases at the same joint in the year prior/after baseline were excluded. Comorbidities associated with OA in the literature and present in ≥1% of the study population were included. Clusters of comorbidities were identified at baseline using latent class analysis (LCA), a soft clustering method that classifies individuals according to the distribution of their measured items. The number of clusters or sub-groups within the study population was decided by comparing goodness of fit parameters (CAIC, BIC, ABIC) and log-likelihood changes of models from 2 to 8 clusters. The selected model was externally evaluated by a survival analysis assessing 10 years mortality within each cluster, where the weight of the posterior probability was used as a probability of sampling weight.

Results

We identified 94,720 individuals with an incident diagnosis of hip OA, 56.3% women and 43.7% men, with a mean age (SD) of 67.2 (13.1) years. We selected the LCA model with 5 clusters that could be described as: healthier (lower prevalence of all comorbidities than average in the cohort), multimorbidity (higher prevalence of all comorbidities, multiple comorbidities), back/neck pain plus mental health (B/N-mental), cardiovascular disease (CVD), and metabolic syndrome (MetS) (Figure 1). Cox regression (HR [95CI%]) showed higher mortality risk for multimorbidity (3.76 [3.70-3.83]), CVD (1.56 [1.53-1.59]) and MetS (4.56 [4.35-4.78]), compared to healthy. No difference was observed for B/N-mental cluster.

Figure 1.

Distribution of comorbidities within each cluster using latent class analysis. Clusters were described as Healthier, Multimorbidity, B/N-mental, CVD and MetS. Black horizontal lines represent the prevalence of the comorbidity before the clusterization. Abbreviations: Healthier, lower prevalence of all comorbidities; Multimorbidity, higher prevalence of all comorbidities; B/N-mental, back/neck pain plus mental health disorders; CVD, cardiovascular disease; Met, metabolic syndrome; Bhp, benign prostate hypertrophy; Chd, chronic heart disease; Chf, chronic heart failure; Ckd, chronic kidney disease; Copd, chronic obstructive pulmonary disease; Gbs, gall bladder stone; Gerd, gastroesophageal reflux disease; Ibd, inflammatory bowel disease; Ovd, other vessel diseases; Substance, substance abuse.

Conclusion

Clustering of co-morbidities in hip OA patients at the time of diagnosis has the potential to detect sub-groups of hip OA patients who might require additional care.

References

[1]Swain, S., A. Sarmanova, C. Coupland, M. Doherty and W. Zhang (2020). “Comorbidities in Osteoarthritis: A Systematic Review and Meta-Analysis of Observational Studies.” Arthritis Care Res (Hoboken) 72(7): 991-1000.

Acknowledgements

We thank the Patient Research Participants (PRP) members Jenny Cockshull, Stevie Vanhegan, and Irene Pitsillidou for their involvement since the beginning of the project. We would like to thank the FOREUM for financially supporting the research.

Disclosure of Interests

None declared

Comorbidities in osteoarthritis (ComOA): a combined cross-sectional, case-control and cohort study using large electronic health records in four European countries

INTRODUCTION

Osteoarthritis (OA) is one of the leading chronic conditions in the older population. People with OA are more likely to have one or more other chronic conditions than those without. However, the temporal associations, clusters of the comorbidities, role of analgesics and the causality and variation between populations are yet to be investigated. This paper describes the protocol of a multinational study in four European countries (UK, Netherlands, Sweden and Spain) exploring comorbidities in people with OA.

METHODS AND ANALYSIS

This multinational study will investigate (1) the temporal associations of 61 identified comorbidities with OA, (2) the clusters and trajectories of comorbidities in people with OA, (3) the role of analgesics on incidence of comorbidities in people with OA, (4) the potential biomarkers and causality between OA and the comorbidities, and (5) variations between countries.A combined case-control and cohort study will be conducted to find the temporal association of OA with the comorbidities using the national or regional health databases. Latent class analysis will be performed to identify the clusters at baseline and joint latent class analysis will be used to examine trajectories during the follow-up. A cohort study will be undertaken to evaluate the role of non-steroidal anti-inflammatory drugs (NSAIDs), opioids and paracetamol on the incidence of comorbidities. Mendelian randomisation will be performed to investigate the potential biomarkers for causality between OA and the comorbidities using the UK Biobank and the Rotterdam Study databases. Finally, a meta-analyses will be used to examine the variations and pool the results from different countries.

ETHICS AND DISSEMINATION

Research ethics was obtained according to each database requirement. Results will be disseminated through the FOREUM website, scientific meetings, publications and in partnership with patient organisations.

Proteomics profiling of human synovial fluid suggests increased protein interplay in early-osteoarthritis (OA) that is lost in late-stage OA

The underlying molecular mechanisms in osteoarthritis (OA) development are largely unknown. This study explores the proteome and the pairwise interplay of proteins in synovial fluid from patients with late-stage knee OA (arthroplasty), early knee OA (arthroscopy due to degenerative meniscal tear), and from deceased controls without knee OA. Synovial fluid samples were analyzed using state-of-the-art mass spectrometry with data-independent acquisition. The differential expression of the proteins detected was clustered and evaluated with data mining strategies and a multilevel model. Group-specific slopes of associations were estimated between expressions of each pair of identified proteins to assess the co-expression (i.e., interplay) between the proteins in each group. More proteins were increased in early-OA versus controls than late-stage OA versus controls. For most of these proteins, the fold changes between late-stage OA versus controls and early-stage OA versus controls were remarkably similar suggesting potential involvement in the OA process. Further, for the first time, this study illustrated distinct patterns in protein co-expression suggesting that the interplay between the protein machinery is increased in early-OA and lost in late-stage OA. Further efforts should focus on earlier stages of the disease than previously considered.

•

Synovial fluid proteomics study of different stages of osteoarthritis (OA).

•

Higher catabolic activity is found in both early- and late-stage OA.

•

Imbalance of the metabolic homeostasis in late-stage OA.

•

Understanding early-stage OA may lead to finding better effective therapies.

Association of Tramadol vs Codeine Prescription Dispensation With Mortality and Other Adverse Clinical Outcomes

IMPORTANCE

Although tramadol is increasingly used to manage chronic noncancer pain, few safety studies have compared it with other opioids.

OBJECTIVE

To assess the associations of tramadol, compared with codeine, with mortality and other adverse clinical outcomes as used in outpatient settings.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective, population-based, propensity score-matched cohort study using a primary care database with routinely collected medical records and pharmacy dispensations covering more than 80% of the population of Catalonia, Spain (≈6 million people). Patients 18 years or older with 1 or more year of available data and dispensation of tramadol or codeine (2007-2017) were included and followed up to December 31, 2017.

EXPOSURES

New prescription dispensation of tramadol or codeine (no dispensation in the previous year).

MAIN OUTCOMES AND MEASURES

Outcomes studied were all-cause mortality, cardiovascular events, fractures, constipation, delirium, falls, opioid abuse/dependence, and sleep disorders within 1 year after the first dispensation. Absolute rate differences (ARDs) and hazard ratios (HRs) with 95% confidence intervals were calculated using cause-specific Cox models.

RESULTS

Of the 1 093 064 patients with a tramadol or codeine dispensation during the study period (326 921 for tramadol, 762 492 for codeine, 3651 for both drugs concomitantly), a total of 368 960 patients (184 480 propensity score-matched pairs) were included after study exclusions and propensity score matching (mean age, 53.1 [SD, 16.1] years; 57.3% women). Compared with codeine, tramadol dispensation was significantly associated with a higher risk of all-cause mortality (incidence, 13.00 vs 5.61 per 1000 person-years; HR, 2.31 [95% CI, 2.08-2.56]; ARD, 7.37 [95% CI, 6.09-8.78] per 1000 person-years), cardiovascular events (incidence, 10.03 vs 8.67 per 1000 person-years; HR, 1.15 [95% CI, 1.05-1.27]; ARD, 1.36 [95% CI, 0.45-2.36] per 1000 person-years), and fractures (incidence, 12.26 vs 8.13 per 1000 person-years; HR, 1.50 [95% CI, 1.37-1.65]; ARD, 4.10 [95% CI, 3.02-5.29] per 1000 person-years). No significant difference was observed for the risk of falls, delirium, constipation, opioid abuse/dependence, or sleep disorders.

CONCLUSIONS AND RELEVANCE

In this population-based cohort study, a new prescription dispensation of tramadol, compared with codeine, was significantly associated with a higher risk of subsequent all-cause mortality, cardiovascular events, and fractures, but there was no significant difference in the risk of constipation, delirium, falls, opioid abuse/dependence, or sleep disorders. The findings should be interpreted cautiously, given the potential for residual confounding.

Transcription Factor RBPJL Is Able to Repress Notch Target Gene Expression but Is Non-Responsive to Notch Activation

Simple Summary

The transcription factor RBPJ is an integral part of the Notch signaling cascade. RBPJ can function as a coactivator when Notch signaling is activated but acts as a repressor in the absence of a Notch stimulus. Here, we characterized the function of RBPJL, a pancreas-specific paralog of RBPJ. Upon depletion of RBPJ using CRISPR/Cas9, we observed specific upregulation of Notch target gene expression. Reconstitution with RBPJL can compensate for the lack of RBPJ function in the repression of Notch target genes but is not able to mediate the Notch-dependent activation of gene expression. On the molecular level, we identified a limited capacity of RBPJL to interact with activated Notch1–4.

Abstract

The Notch signaling pathway is an evolutionary conserved signal transduction cascade present in almost all tissues and is required for embryonic and postnatal development, as well as for stem cell maintenance, but it is also implicated in tumorigenesis including pancreatic cancer and leukemia. The transcription factor RBPJ forms a coactivator complex in the presence of a Notch signal, whereas it represses Notch target genes in the absence of a Notch stimulus. In the pancreas, a specific paralog of RBPJ, called RBPJL, is expressed and found as part of the heterotrimeric PTF1-complex. However, the function of RBPJL in Notch signaling remains elusive. Using molecular modeling, biochemical and functional assays, as well as single-molecule time-lapse imaging, we show that RBPJL and RBPJ, despite limited sequence homology, possess a high degree of structural similarity. RBPJL is specifically expressed in the exocrine pancreas, whereas it is mostly undetectable in pancreatic tumour cell lines. Importantly, RBPJL is not able to interact with Notch−1 to −4 and it does not support Notch-mediated transactivation. However, RBPJL can bind to canonical RBPJ DNA elements and shows migration dynamics comparable to that of RBPJ in the nuclei of living cells. Importantly, RBPJL is able to interact with SHARP/SPEN, the central corepressor of the Notch pathway. In line with this, RBPJL is able to fully reconstitute transcriptional repression at Notch target genes in cells lacking RBPJ. Together, RBPJL can act as an antagonist of RBPJ, which renders cells unresponsive to the activation of Notch.

Knee and hip osteoarthritis and risk of nine cancers in a large real-world matched cohort study

OBJECTIVES

Joint replacement due to end-stage osteoarthritis (OA) has been linked to incidence of several cancers. We aimed to estimate the association between newly diagnosed knee and hip OA and incidence of nine common cancer types.

METHODS

We identified persons with incident knee or hip OA, aged ≥40 years, between 2009 and 2015 in the SIDIAP database in Catalonia, Spain. We matched up to 3 OA-free controls on age, sex and general practitioner. We followed participants from 1 year after OA diagnosis until migration, death, end of study at Dec 31st 2017 or incident cancer of: stomach, colorectal, liver, pancreas, lung, skin, breast, prostate, and bladder. We used flexible parametric survival models, adjusted for confounders. Estimates were corrected for misclassification using probabilistic bias analysis.

RESULTS

We included 117 750 persons with knee OA and matched 309 913 persons without, with mean (SD) age of 67.5 (11.1) years and 63% women. The hip cohort consisted of 39 133 persons with hip OA and 116 713 controls. For most of included cancers, the hazard ratios (HRs) were close to 1. The HR of lung cancer for knee OA exposure was 0.80 (95%CI 0.71, 0.89) and attenuated to 0.98 (0.76, 1.27) in non-smokers. The hazard of colorectal cancer was lower in persons with both knee and hip OA by 10-20%.

CONCLUSIONS

Knee and hip OA are not associated with studied incident cancers, apart from lower risk of colorectal cancer. The often-reported protective association of knee OA with lung cancer is explained by residual confounding.

Relationship Between Magnetic Resonance Imaging Features and Knee Pain Over Six Years in Knees Without Radiographic Osteoarthritis at Baseline

Objective

To explore whether magnetic resonance imaging (MRI) features suggestive of knee osteoarthritis (OA) are associated with presence of knee pain in possible early‐stage OA development.

Methods

We included 294 participants from the Osteoarthritis Initiative (mean ± SD age 50 ± 3 years; 50% women) with baseline Kellgren/Lawrence grade of 0 in both knees, all of whom had received knee MRIs at 4 different time points over 6 years (baseline, 24, 48, and 72 months). Using a linear mixed model (knees matched within individuals), we studied whether MRI features (meniscal body extrusion [in mm], cartilage area loss [score 0–39], cartilage full thickness loss [range 0–16], osteophytes [range 0–29], meniscal integrity [range 0–10], bone marrow lesions [BMLs] including bone marrow cysts [range 0–20], Hoffa‐ or effusion‐synovitis [absent/present], and popliteal cysts [absent/present]) were associated with knee‐specific pain as reported on the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire using a 0–100 scale (worst to best).

Results

The differences in KOOS knee pain score for a knee with a 1 unit higher score on MRI were the following: meniscal extrusion –1.52 (95% confidence interval [95% CI] –2.35, –0.69); cartilage area loss –0.23 (95% CI –0.48, 0.02); cartilage full thickness loss –1.04 (95% CI –1.58, –0.50); osteophytes –0.32 (95% CI –0.61, –0.03); meniscal integrity –0.28 (95% CI –0.58, 0.02); BMLs including potential cysts –0.19 (95% CI –0.55, 0.16); synovitis 0.23 (95% CI –1.14, 1.60); and popliteal cysts 0.86 (95% CI –0.56, 2.29).

Conclusion

Meniscal extrusion, full thickness cartilage loss, and osteophytes are associated with having more knee pain. Although these features may be relevant targets for future trials, the clinical relevance of our findings is unclear because no feature was associated with a clinically important difference in knee pain.

What Are the Patient-reported Outcomes of Trapeziectomy and Tendon Suspension at Long-term Follow-up?

BACKGROUND

There are multiple options for the treatment of thumb carpometacarpal joint osteoarthritis (CMC1 OA), with evidence for pain relief and improved function. Although simple trapeziectomy has the lowest complication risk, tendon suspension of the first metacarpal and interposition is still the most commonly used surgical procedure in patients with CMC1 OA. Although there are several reports of good short-term results after trapeziectomy and tendon suspension-interposition arthroplasty, few studies have evaluated long-term outcomes. This study is one of the largest and longest follow-up evaluations of a cohort of patients with CMC1 OA who were treated with trapeziectomy and suspension-interposition arthroplasty, capturing 96% of the original cohort for evaluation.

QUESTIONS/PURPOSES

(1) After trapeziectomy and tendon suspension surgery, what are the long-term, patient-reported outcomes and clinical measurements (strength and ROM); and in unilateral procedures, how do these parameters compare with those of the contralateral hand that was not operated on? (2) What is the mean subsidence (unloaded trapezial space), and does pinch strength correlate with the amount of subsidence?

METHODS

From 1998 to 2005, 130 patients underwent trapeziectomy and abductor pollicis longus (APL) suspension-interposition arthroplasty for CMC1 OA at one orthopaedic department. During this period, 15 patients were treated with CMC1 arthrodesis and four were treated with implant arthroplasty, for a total of 149 patients. The surgeons used APL suspensionplasty for most patients, based on age and expected postoperative function; they also employed this procedure to avoid hardware or implant failure issues. The 100 living patients were asked to participate in this retrospective study, 96% (96) of whom were enrolled. The mean age at surgery was 58 ± 7 years. The patients completed a two-item thumb pain scale (modified from the SF-36 body pain scale), a hand pain VAS (average level of pain experienced over the week preceding measurement), and the 11-item QuickDASH. Patient-reported outcomes data were obtained from all 96 patients, and 83% (80) of patients underwent bilateral hand radiography and a physical examination at a mean follow-up of 17 ± 2.4 years. We calculated outcome data for each patient, and in 39 patients with unilateral surgery and intact contralateral CMC1 joint, we compared the operated side with the contralateral side. We compared our outcome data with that from the Swedish National Quality Registry for Hand Surgery (HAKIR), noting comparable outcomes for pain and QuickDASH scores.

RESULTS

At long-term follow-up after trapeziectomy and APL suspension surgery, the mean thumb pain score was 19 ± 26, hand pain VAS score 23 ± 25, and QuickDASH score 26 ± 21. In the patients with unilateral surgery and intact contralateral CMC1 joint, the thumb pain score for the operated side was lower than the contralateral side, specifically 19 ± 25 compared with 29 ± 30 (mean difference -9.8 [95% CI -19.5 to -0.2]; p = 0.045); hand pain VAS score was 24 ± 23 versus 30 ± 25 (mean difference -6.1 [95% CI -15.2 to 3.1]; p = 0.19), and the QuickDASH score was 27 ± 19. Grip strength showed no differences between the operated and contralateral sides (mean 16.7 ± 7.3 kg versus 16.6 ± 6.9 kg, mean difference 0.1 [95% CI -1.6 to 1.8]; p = 0.90), while pinch was different (4.4 ± 1.4 versus 5.0 ± 1.5 kg, mean difference -0.6 [95% CI -0.9 to -0.3]; p = 0.001). The mean trapezial space was 4.4 ± 2.2 mm, and there was no association between the trapezial space and pinch strength (0.07 kg [95% CI -0.04 to 0.18] per mm of space; p = 0.17).

CONCLUSION

The finding of comparable pain and function between operated and unoperated sides at long-term follow-up suggests that trapeziectomy and tendon suspension-interposition arthroplasty provides predictable outcomes, and surgeons can use these data to counsel patients that surgery can potentially return them to comparable use. However, as patients often have asymptomatic radiographic OA on the contralateral side, future studies are needed to examine the impact of asymptomatic disease on function.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Cardiovascular drug treatment, statins and biopsy-confirmed giant cell arteritis: a population-based case-control study

Objective

To determine whether exposure to cardiovascular medications and statins is associated with increased risk of giant cell arteritis (GCA).

Design

The population-based case–control study comprised a cohort of patients with biopsy-confirmed GCA linked to the Swedish Prescribed Drug Register to identify all exposure to drugs prior to diagnosis of GCA. Ten controls per GCA case, matched for age, sex and residential area, were included. Using corresponding Anatomical Therapeutic Chemical codes, ACE inhibitors, angiotensin II receptor blockers, beta-blocking agents, calcium antagonists, diuretics, statins and cardiac therapy drugs were investigated from July 1, 2005 to the diagnosis/index date. A conditional logistic regression model was fitted adjusted for income, education level and marital status. We repeated the analyses including only new drug users excluding those with any prescription during the year from July 1, 2005 to July 1, 2006.

Results

574 cases (29% men) of diagnosed GCA and 5740 controls (29% men) were included. The mean age at diagnosis is 75 years (SD 8). Of the GCA cases, 71% had at least one dispensation of a cardiovascular drug prior to the index date, compared to 74% of controls. The ORs for the association of target drug exposure with GCA were <1 for most drugs, but close to 1 in the analysis of new users. Statins were consistently associated with lower risk of GCA, OR 0.74 (95% CI 0.61 to 0.90).

Conclusion

Statins may be associated with lower risk of incident biopsy-confirmed GCA. No association was evident for other studied drugs.

The impact of first and second wave of COVID-19 on knee and hip surgeries in Sweden

PURPOSE

To investigate the impact of COVID-19 in Sweden on rates of knee and hip surgeries.

METHODS

We used healthcare data for the population of the southernmost region in Sweden (1.4 million inhabitants). We did an interrupted time-series analysis to estimate changes in rates and trends of joint replacements (JR), arthroscopies, and fracture surgeries for knee or hip in April-December 2020 compared to pre-COVID-19 levels adjusting for seasonal variations.

RESULTS

We found a drop of 54% (95% CI 42%; 68%) and 42% (95% CI 32%; 52%), respectively, in the rate of JRs and arthroscopies in April 2020 when compared to the counterfactual scenario. This was followed by an increase that brought the rates of JRs and arthroscopies back to their predicted levels also during the beginning of the second wave (November-December 2020). Acute fracture surgeries were largely unaffected, i.e. did not show any decrease as observed for the other surgeries.

CONCLUSIONS

In southern Sweden, we observed a marked decrease in elective knee and hip surgeries following the first wave of Covid-19. The rates remained close to normal during the beginning of the second wave suggesting that important elective surgeries for patients with end-stage osteoarthritis can still be offered despite an ongoing pandemic provided adequate routines and hospital resources.

The heritability of doctor-diagnosed traumatic and degenerative meniscus tears

OBJECTIVE

To estimate the genetic contribution to traumatic and degenerative meniscus tears for men and women across the lifespan.

METHODS

We linked the Swedish Twin Register with individual-level national healthcare data to form a 30-year, population-wide, longitudinal twin cohort. To study genetic contribution to meniscus tears, we estimated the heritability and familial risk using incident traumatic and degenerative tear diagnostic codes in a cohort of 88,414 monozygotic and dizygotic twin-pairs, aged ≥17 years.

RESULTS

During follow-up, 3,372 (3.8%) of 88,414 twins were diagnosed with a traumatic or degenerative meniscus tear. The heritability was 0.39 (95% CI = 0.32-0.47) for men and 0.43 (95% CI = 0.36-0.50) for women, and did not vary by age. Environmental factors that were unique to each twin in a pair explained a greater proportion of the variance than genetic factors, both for men (0.61, 95% CI = 0.53-0.68) and women (0.57, 95% CI = 0.50-0.64). Separate analyses of traumatic vs degenerative meniscus tears yielded similar results.

CONCLUSION

For the first time, we have estimated the genetic contribution to doctor-diagnosed meniscus tears using a twin study design. We found a relatively low to modest heritability for meniscus tears (∼40%). The heritability was also fairly stable over the lifespan, and equal in both men and women. Our findings suggest that environmental risk factors are a more important contributor to both traumatic and degenerative doctor-diagnosed meniscus tears than genetic factors.

Risk of comorbidities following physician-diagnosed knee or hip osteoarthritis: a register-based cohort study

OBJECTIVE

To estimate the risk of developing comorbidities in patients after physician-diagnosed knee or hip osteoarthritis (OA).

DESIGN

Cohort study using Swedish longitudinal healthcare register data; we studied residents in the Skåne region aged ≥35 years at January 1, 2010 free from diagnosed hip or knee OA (n= 548,681). We then identified subjects with at least one new diagnosis of knee or hip OA (incident OA) between 2010 and 2017 (n=50,942 considered exposed). Subjects without diagnosed OA were considered unexposed. From January 2010 both unexposed and exposed subjects were observed for the occurrence of 18 different pre-defined comorbidities until either relocation outside of the region, death, occurrence of the comorbidity, or December 2017, whichever came first. We calculated unadjusted and adjusted hazard ratios (HR, aHR) of comorbidities using Cox models with knee and hip OA as time-varying exposures.

RESULTS

Subjects with incident knee or hip OA had 7% to 60% higher adjusted hazards (aHR between 1.07 to 1.60), of depression, cardiovascular diseases, back pain, and osteoporosis than individuals without an OA diagnosis. An increased risk of diabetes was found only for knee OA (aHR 1.19, 95% CI 1.13-1.26). For the rest of the diagnoses, we found either no increased risk or estimates with wide confidence intervals, excluding clear interpretations of the direction or size of effects.

CONCLUSIONS

Incident physician-diagnosed knee and hip OA is associated with increased risk of depression, cardiovascular diseases, back pain, osteoporosis, and diabetes. However, the latter only for knee OA.

AB0678 RATES OF SURGICAL PROCEDURES OF THE KNEE AND HIP DURING THE “FIRST WAVE” OF COVID 19 IN SWEDEN

Background:

Many countries imposed lockdowns in March 2020, in anticipation of the “first wave” of COVID-19 and the massive healthcare resources required to meet its acute medical needs. Sweden adopted a different strategy to contain the epidemic, opting for non-binding recommendations. Nonetheless, elective and acute surgical procedures in health care may have been affected.

Objectives:

To investigate the effect of the “first-wave” of COVID-19 and the government’s response in Sweden on the rates of total joint replacements (TJR), arthroscopies, and fracture surgeries of the knee and hip.

Methods:

We used register data for the entire population of Skåne, the southernmost region in Sweden with 1.3 million inhabitants (13% of the total Swedish population). We identified all residents aged ≥18 years who between 1st January 2015 and 31st November 2020 underwent any of the following surgical procedures of the knee or hip: TJR (TJR due to fracture excluded), arthroscopy, and surgery due to fracture (including TJR). To demarcate pre-event and post-event periods, we established a differentiation point corresponding to mid-March 2020, the timepoint at which the the Swedish Public Health Agency began recommending social distancing, working from home, distance learning for secondary schools and universities,. At the aggregate level, we modelled the number of surgeries per 10,000 adults from January 2015 up to September 2020. We did an interrupted time-series (ITSA) analysis using segmented ordinary least-squares regression to estimate changes in the levels and trends of surgical procedures compared to pre-COVID-19 levels, adjusting for seasonal variations. The month of March was treated as a “phase-in” period to give time for the new recommendations to be implemented. In addition, we estimated the absolute and relative difference (with its 95% confidence interval [CI]) between the predicted and the counterfactual scenario in the monthly number of surgeries from April 2020, where the counterfactual is the rate of surgery that would have been expected if COVID-19 had not happened. To account for the possibility that other co-occurring events may be responsible for the observed changes, we assessed changes in the number of surgeries due to fractures, which are normally treated as emergencies that cannot be cancelled or rescheduled, and thus should be less affected, at least by policies at the hospital level.

Results:

We identified a total of 20,831 TJRs, 12,156 arthroscopies and 15,041 fracture surgeries of the knee or hip over the study period. The monthly rate of surgeries and ITSAs are presented in Figure 1, with the pre-COVID period starting from February 2019 for readability (Figure 1). The results suggest that in April 2020, there was a decrease of 2.08 (95%CI 1.81; 2.35) TJRs per 10,000 adults which corresponds to a decrease of 74% (95%CI 65%; 85%) when compared to the counterfactual scenario. This was followed by a positive trend signifying a monthly increase of 0.36 (95%CI 0.31; 0.40) TJRs per 10,000 adults. The rate of arthroscopies followed a similar pattern with a decrease of 0.55 (95%CI 0.39; 0.71) arthroscopies per 10,000 adults in April, which corresponds to a 49% decrease (95%CI 28%; 63%) followed by a positive trend signifying a monthly increase of 0.11 (95%CI 0.07; 0.15) arthroscopies per 10,000 adults. The rate of surgery due to knee or hip fractures showed no decrease in April and was followed by a negative trend signifying a monthly decrease of 0.03 (95%CI 0.002; 0.04) surgeries per 10,000 adults.

Conclusion:

In Sweden, we observed a marked decrease in the number of typical elective knee and hip surgeries such as TJRs and arthroscopies, following the government’s response to Covid-19. We then observed a slow but steady recovery that brought the rates of procedures towards expected levels by Fall 2020, before the “second wave” hit the country. The number of acute fracture surgeries showed no sharp drop, instead showing a steady and slow decline potentially due to reduction in commuting and in physical activities linked to recommendations of social

Disclosure of Interests:

None declared

Is meniscal status in the anterior cruciate ligament injured knee associated with change in bone surface area? An exploratory analysis of the KANON trial

OBJECTIVES

To study bone shape changes as a potential early feature of post-traumatic structural knee OA development, we estimated the association between meniscal status in the anterior cruciate ligament (ACL) injured knee and longitudinal condyle changes in bone surface area.

DESIGN

We used data from the KANON trial, including 121 young ACL-injured adults. We obtained baseline and 2-year follow-up knee MRIs. Our outcome was change in the bone surface areas (mean mm2, log-transformed) in 4 locations (femur, tibia, patella, and trochlea femur) in the medial and lateral compartment from baseline to 2 years. Meniscal pathology was defined as both present at baseline and newly developed (i.e., incident or progressed) using ACLOAS. We used multilevel linear regression adjusted for baseline bone area, age, sex, body mass index, treatment arm (i.e., early or optional delayed ACL reconstruction), and location. We analyzed medial and lateral compartment separately. We present results as percentage (%) bone area change difference with 95% confidence intervals (CI).

RESULTS

We analyzed 109 subjects (median 27 (18-36) years, 83% men) due to missing MRI information. The bone surface area increased on average by ∼2% over 2 years. The differences between knees with and without baseline meniscal pathology were 1.1% (95%CI 0.0-2.3%) and 1.4% (95%CI 0.6-2.2%) in the medial and lateral compartment, respectively, and 1.2% (95%CI 0.3-2.0%) and 1.3% (95%CI 0.6-2.0%) for medial and lateral newly developed pathology, respectively.

CONCLUSION

Our finding of ∼1% increase bone area in compartment with meniscal pathology suggests a potentially important association between meniscal integrity and early bone surface area changes after ACL injury. Trial registration number ISRCTN 84752559.

Quantitative three-dimensional collagen orientation analysis of human meniscus posterior horn in health and osteoarthritis using micro-computed tomography

OBJECTIVE

Knee osteoarthritis (OA) is associated with meniscal degeneration that may involve disorganization of the meniscal collagen fiber network. Our aims were to quantitatively analyze the microstructural organization of human meniscus samples in 3D using micro-computed tomography (μCT), and to compare the local microstructural organization between OA and donor samples.

METHOD

We collected posterior horns of both medial and lateral human menisci from 10 end-stage medial compartment knee OA patients undergoing total knee replacement (medial & lateral OA) and 10 deceased donors without knee OA (medial & lateral donor). Posterior horns were dissected and fixed in formalin, dehydrated in ascending ethanol concentrations, treated with hexamethyldisilazane (HMDS), and imaged with μCT. We performed local orientation analysis of collagenous microstructure in 3D by calculating structure tensors from greyscale gradients within selected integration window to determine the polar angle for each voxel.

RESULTS

In donor samples, meniscus bundles were aligned circumferentially around the inner border of meniscus. In medial OA menisci, the organized structure of collagen network was lost, and main orientation was shifted away from the circumferential alignment. Quantitatively, medial OA menisci had the lowest mean orientation angle compared to all groups, -24° (95%CI -31 to -18) vs medial donor and -25° (95%CI -34 to -15) vs lateral OA.

CONCLUSIONS

HMDS-based μCT imaging enabled quantitative analysis of meniscal collagen fiber bundles and their orientations in 3D. In human medial OA menisci, the collagen disorganization was profound with overall lower orientation angles, suggesting collagenous microstructure disorganization as an important part of meniscus degradation.

Phospho-Site Mutations in Transcription Factor Suppressor of Hairless Impact Notch Signaling Activity During Hematopoiesis in Drosophila

The highly conserved Notch signaling pathway controls a multitude of developmental processes including hematopoiesis. Here, we provide evidence for a novel mechanism of tissue-specific Notch regulation involving phosphorylation of CSL transcription factors within the DNA-binding domain. Earlier we found that a phospho-mimetic mutation of the Drosophila CSL ortholog Suppressor of Hairless [Su(H)] at Ser269 impedes DNA-binding. By genome-engineering, we now introduced phospho-specific Su(H) mutants at the endogenous Su(H) locus, encoding either a phospho-deficient [Su(H) S269A ] or a phospho-mimetic [Su(H) S269D ] isoform. Su(H) S269D mutants were defective of Notch activity in all analyzed tissues, consistent with impaired DNA-binding. In contrast, the phospho-deficient Su(H) S269A mutant did not generally augment Notch activity, but rather specifically in several aspects of blood cell development. Unexpectedly, this process was independent of the corepressor Hairless acting otherwise as a general Notch antagonist in Drosophila. This finding is in agreement with a novel mode of Notch regulation by posttranslational modification of Su(H) in the context of hematopoiesis. Importantly, our studies of the mammalian CSL ortholog (RBPJ/CBF1) emphasize a potential conservation of this regulatory mechanism: phospho-mimetic RBPJ S221D was dysfunctional in both the fly as well as two human cell culture models, whereas phospho-deficient RBPJ S221A rather gained activity during fly hematopoiesis. Thus, dynamic phosphorylation of CSL-proteins within the DNA-binding domain provides a novel means to fine-tune Notch signal transduction in a context-dependent manner.

Socioeconomic inequalities in all-cause and cause-specific mortality among patients with osteoarthritis in the Skåne region, Sweden

OBJECTIVE

To assess the association between education and all-cause and cause-specific mortality among patients with osteoarthritis (OA) in comparison to an OA-free reference cohort.

METHODS

Using data from the Skåne healthcare register, we identified all residents aged ≥45 years in the region of Skåne, with doctor-diagnosed OA of peripheral joints between 1998 and 2013 (n=123,993). We created an age and sex-matched reference cohort without OA diagnosis (n=121,318). Subjects were followed until death, relocation outside Skåne, or the end of 2014. The relative index of inequality (RII) and the slope index of inequality (SII) were estimated by the Cox model and Aalen´s additive hazard model, respectively.

RESULTS

We found an inverse association between education and mortality. The magnitude of relative inequalities in all-cause mortality were comparable in the OA (RII 1.53, 95% CI:1.46, 1.61) and reference cohorts (RII:1.54, 95% CI:1.47, 1.62). The absolute inequalities were smaller in the OA (SII 937 all-cause deaths per 100,000 person-years, 95% CI:811, 1063) compared with the reference cohort (SII 1265, 95% CI:1109, 1421). Cardiovascular mortality contributed more to the absolute inequalities in the OA than in the reference cohort (60.1% vs. 48.1%) while the opposite was observed for cancer mortality (8.5% vs. 22.3%).

CONCLUSION

We found higher all-cause and cause-specific mortality in OA patients with lower education. The observed inequalities in the OA cohort reflect the inequalities in the population at large. The greater burden of cardiovascular diseases in OA patients suggests that proper management of cardiovascular risk factors in OA patients is important.

Epidemiology of biopsy-confirmed giant cell arteritis in southern Sweden - an update on incidence and first prevalence estimate

Objective

To characterize the epidemiology of temporal artery biopsy-positive (TAB+) GCA, including trends in incidence, seasonal variation and prevalence in Skåne, the southernmost region of Sweden.

Methods

All histopathology reports of TABs from 1997 through 2019 were reviewed to identify patients diagnosed with TAB+ GCA. Incidence rates based on the 23-year period and the point-prevalence at 31 December 2014 were determined. An alternative prevalence calculation included only TAB+ GCA patients living in the study area and receiving immunosuppressant therapy on the point-prevalence date.

Results

One thousand three hundred and sixty patients were diagnosed with TAB+ GCA (71% female). The average annual incidence 1997–2019 was 13.3 (95% CI: 12.6, 14.0) per 100 000 inhabitants aged ≥50 years and was higher in females (17.8; 95% CI: 16.7, 18.9) than in males (8.2; 95% CI: 7.4, 9.0). The age- and sex-standardized incidence declined from 17.3 in 1997 to 8.7 in 2019, with incidence ratio (IR) of 0.98 per year (95% CI: 0.98, 0.99). A seasonal variation was observed with higher incidence during spring than winter [IR = 1.19 (95% CI: 1.03, 1.39)]. The overall point-prevalence of TAB+ GCA was 127.1/100 000 (95% CI: 117, 137.3) and was 75.5 (95% CI: 67.7, 83.3) when including only patients receiving immunosuppressants.

Conclusion

Over the past 2 decades, the incidence of biopsy-confirmed GCA has decreased by ∼2% per year. Still, a high prevalence of GCA on current treatment was observed. More cases are diagnosed during spring and summer than in the winter.

Trajectory of Healthcare Resource Utilization in Giant Cell Arteritis: A Population-based Study

OBJECTIVE

To estimate the healthcare resource utilization (HRU) in patients with giant cell arteritis (GCA) compared with the general population in southern Sweden.

METHODS

The study sample comprised 653 patients with GCA along with 10 age-, sex-, and residency area-matched reference subjects per patient. Data on public and private healthcare consultations and hospitalizations were extracted from the Skåne Healthcare Register. We assessed trajectories of primary and specialist healthcare visits, as well as hospital admissions and inpatient days from 3 years before through 5 years after the date of GCA diagnosis for patients and matched references. HRU was analyzed using generalized estimating equations adjusted for sex, age at the index year, calendar year of diagnosis, education, income, marital status, place of birth, and Charlson Comorbidity Index. Inverse probability weighting was used to account for dropout during study.

RESULTS

Patients with GCA had higher rates of healthcare visits than the references from the year before GCA diagnosis and up to 4 years after diagnosis, with the largest relative (rate ratio 1.85, 95% CI 1.68-2.05) and absolute (mean difference 10.2, 95% CI 8.1-12.3 visits per person) differences in the year of diagnosis. Similar trajectories were observed for primary and specialist healthcare visits. For hospital admissions and inpatient days, the differences disappeared 1 year after diagnosis date.

CONCLUSION

Patients with GCA utilized healthcare services at a significantly higher rate than the reference population. The increased utilization among Swedish patients with GCA was evident 1 year before and prolonged up to 4 years after diagnosis date.

High genetic contribution to anterior cruciate ligament rupture: Heritability ~69

OBJECTIVES

We aimed to determine the lifetime genetic risk for anterior cruciate ligament (ACL) rupture.

METHODS

We used a twin study approach, linking the Swedish Twin Register with national healthcare data to form a 30 year, population wide, longitudinal twin cohort. We studied ACL rupture in this cohort of 88 414 identical and fraternal twins, aged ≥17 years, to determine the familial risk and heritability of ACL rupture.

RESULTS

The incidence rate of ACL rupture was 70 (95% CI 66 to 74) per 100 000 person years. The familial risk, which is the excess risk ratio (RR) of the second twin having ACL rupture given that the first twin has had such a rupture, was higher in identical twin pairs (RR=8.6, 95% CI 6.2 to 11.0) than in fraternal twin pairs (RR=1.9, 95% CI 0.9 to 3.0). The overall heritability of ACL rupture was high, 69% (95% CI 47 to 91), increasing from 60% at age 17 years to 80% at age 60 years. Women and men had similar familial risk and heritability of ACL rupture.

CONCLUSION

The genetic contribution to ACL rupture of ~69% is high and suggests strong familial clustering. If clinicians recognise the high genetic risk of such injury, they may be better able to counsel athletes whose near relatives have had ACL rupture.

Probabilistic Quantification of Bias to Combine the Strengths of Population-Based Register Data and Clinical Cohorts-Studying Mortality in Osteoarthritis

We propose combining population-based register data with a nested clinical cohort to correct misclassification and unmeasured confounding through probabilistic quantification of bias. We have illustrated this approach by estimating the association between knee osteoarthritis and mortality. We used the Swedish Population Register to include all persons resident in the Skåne region in 2008 and assessed whether they had osteoarthritis using data from the Skåne Healthcare Register. We studied mortality through year 2017 by estimating hazard ratios. We used data from the Malmö Osteoarthritis Study (MOA), a small cohort study from Skåne, to derive bias parameters for probabilistic quantification of bias, to correct the hazard ratio estimate for differential misclassification of the knee osteoarthritis diagnosis and confounding from unmeasured obesity. We included 292,000 persons in the Skåne population and 1,419 from the MOA study. The adjusted association of knee osteoarthritis with all-cause mortality in the MOA sample had a hazard ratio of 1.10 (95% confidence interval (CI): 0.80, 1.52) and was thus inconclusive. The naive association in the Skåne population had a hazard ratio of 0.95 (95% CI: 0.93, 0.98), while the bias-corrected estimate was 1.02 (95% CI: 0.59, 1.52), suggesting high uncertainty in bias correction. Combining population-based register data with clinical cohorts provides more information than using either data source separately.

Arthroscopic partial meniscectomy for a degenerative meniscus tear: a 5 year follow-up of the placebo-surgery controlled FIDELITY (Finnish Degenerative Meniscus Lesion Study) trial

Objectives

To assess the long-term effects of arthroscopic partial meniscectomy (APM) on the development of radiographic knee osteoarthritis, and on knee symptoms and function, at 5 years follow-up.

Design

Multicentre, randomised, participant- and outcome assessor-blinded, placebo-surgery controlled trial.

Setting

Orthopaedic departments in five public hospitals in Finland.

Participants

146 adults, mean age 52 years (range 35–65 years), with knee symptoms consistent with degenerative medial meniscus tear verified by MRI scan and arthroscopically, and no clinical signs of knee osteoarthritis were randomised.

Interventions

APM or placebo surgery (diagnostic knee arthroscopy).

Main outcome measures

We used two indices of radiographic knee osteoarthritis (increase in Kellgren and Lawrence grade ≥1, and increase in Osteoarthritis Research Society International (OARSI) atlas radiographic joint space narrowing and osteophyte sum score, respectively), and three validated patient-relevant measures of knee symptoms and function (Western Ontario Meniscal Evaluation Tool (WOMET), Lysholm, and knee pain after exercise using a numerical rating scale).

Results

There was a consistent, slightly greater risk for progression of radiographic knee osteoarthritis in the APM group as compared with the placebo surgery group (adjusted absolute risk difference in increase in Kellgren-Lawrence grade ≥1 of 13%, 95% CI −2% to 28%; adjusted absolute mean difference in OARSI sum score 0.7, 95% CI 0.1 to 1.3). There were no relevant between-group differences in the three patient-reported outcomes: adjusted absolute mean differences (APM vs placebo surgery), −1.7 (95% CI −7.7 to 4.3) in WOMET, −2.1 (95% CI −6.8 to 2.6) in Lysholm knee score, and −0.04 (95% CI −0.81 to 0.72) in knee pain after exercise, respectively. The corresponding adjusted absolute risk difference in the presence of mechanical symptoms was 18% (95% CI 5% to 31%); there were more symptoms reported in the APM group. All other secondary outcomes comparisons were similar.

Conclusions

APM was associated with a slightly increased risk of developing radiographic knee osteoarthritis and no concomitant benefit in patient-relevant outcomes, at 5 years after surgery.

Trial registration

ClinicalTrials.gov (NCT01052233 and NCT00549172).

Proteomic comparison of osteoarthritic and reference human menisci using data-independent acquisition mass spectrometry

OBJECTIVE

Recent research in knee osteoarthritis (OA) highlights the role of the meniscus in OA pathology. Our aim was to compare the proteomes of medial and lateral menisci from end-stage medial compartment knee OA patients, with reference menisci from knee-healthy deceased donors, using mass spectrometry.

DESIGN

Tissue plugs of Ø3 mm were obtained from the posterior horns of the lateral and medial menisci from one knee of 10 knee-healthy deceased donors and 10 patients undergoing knee replacement. Proteins were extracted and prepared for mass spectrometric analysis. Statistical analysis was conducted on abundance data that was log₂-transformed, using a linear mixed effects model and evaluated using pathway analysis.

RESULTS

We identified a total of 835 proteins in all samples, of which 331 were included in the statistical analysis. The largest differences could be seen between the medial menisci from OA patients and references, with most proteins showing higher intensities in the medial menisci from OA patients. Several matrix proteins, e.g., matrix metalloproteinase 3 (MMP3) (4.3 times higher values [95%CI 1.8, 10.6]), TIMP1 (3.5 [1.4, 8.5]), asporin (4.1 [1.7, 10.0]) and versican (4.4 [1.8, 10.9]), all showed higher abundance in medial menisci from OA patients compared to medial reference menisci. OA medial menisci also showed increased activation of several pathways involved in inflammation.

CONCLUSION

An increase in protein abundance for proteins such as MMP and TIMP1 in the medial menisci from OA patients suggests simultaneous activation of both catabolic and anabolic processes that warrants further attention.

Proteomic characterization of the normal human medial meniscus body using data-independent acquisition mass spectrometry

Recent research suggests an important role of the meniscus in the development of knee osteoarthritis. We, therefore, aimed to analyze the proteome of the normal human meniscus body, and specifically to gain new knowledge on global protein expression in the different radial zones. Medial menisci were retrieved from the right knees of 10 human cadaveric donors, from which we cut a 2 mm radial slice from the mid-portion of the meniscal body. This slice was further divided into three zones: inner, middle, and peripheral. Proteins were extracted and prepared for mass spectrometric analysis using data-independent acquisition. We performed subsequent data searches using Spectronaut Pulsar and used fixed-effect linear regression models for statistical analysis. We identified 638 proteins and after statistical analysis, we observed the greatest number of differentially expressed proteins between the inner and peripheral zones (163 proteins) and the peripheral and middle zones (136 proteins), with myocilin being the protein with the largest fold-change in both comparisons. Chondroadherin was one of eight proteins that differed between the inner and middle zones. Functional enrichment analyses showed that the peripheral one-third of the medial meniscus body differed substantially from the two more centrally located zones, which were more similar to each other. This is probably related to the higher content of cells and vascularization in the peripheral zone, whereas the middle and inner zones of the meniscal body appear to be more similar to hyaline cartilage, with high levels of extracellular matrix proteins such as aggrecan and collagen type II.