Epidemiology of spondyloarthritis in North America

Development of a Mouse Model of Enthesis-Specific NF-κB Activation

Enthesitis, or inflammation specific to sites in the body where tendon inserts into bone, can arise in isolated joints from overuse or in multiple joints as a complication of an autoimmune condition such as psoriatic arthritis or spondyloarthritis. However, the pathogenesis of enthesitis is not well understood, so treatment strategies are limited. A clinically relevant animal model of enthesitis would allow investigators to determine mechanisms driving the disease and evaluate novel therapies. Therefore, we developed a murine model of inducible enthesis-specific inflammation by constitutively activating the NF-κB pathway in Gli1+ cells. Gli1CreERT mice were crossed with IKKβ-overexpression mice and given tamoxifen injections 5 days postnatally to induce enthesitis. Sixteen weeks of IKKβ overexpression in enthesis cells led to impaired mechanical properties, subtle histologic changes, and changes to expression of extracellular matrix- and inflammation-related genes. Increased loading from treadmill overuse activity did not exacerbate this phenotype. Clinical significance: The new murine model may have utility for studying the pathogenesis of enthesitis and approaches to treat the condition.

Association Between Weight-Adjusted Waist Index and the Prevalence of Low Back Pain: A Cross-Sectional Observational Study from National Health and Nutrition Examination Survey

BACKGROUND

The weight-adjusted waist index (WWI) is a novel obesity index that is calculated as the waist circumference (WC) divided by the square root of body weight (kg). Previous studies have revealed that higher body mass index (BMI) and WC increase the risk of low back pain (LBP). However, no research explores the relationship between WWI and LBP.

METHODS

Data utilized in this cross-sectional study were drawn from the National Health and Nutrition Examination Survey. Three logistic regression models were used to evaluate the association between WWI and LBP. Stratified analysis was applied to assess the stability of the results. Receiver-operating characteristic (ROC) curves were employed to visually assess and compare the predictive effectiveness of WWI, BMI, WC, and weight on LBP.

RESULTS

A significant positive correlation was observed between WWI and LBP, model 1 (odds ratio [OR] = 1.222, 95% confidence interval (95% CI) [1.164, 1.283], P < 0.0001), model 2 (OR = 1.187, 95% CI [1.118, 1.261], P < 0.0001), and model 3 (OR = 1.129, 95% CI [1.056, 1.207], P < 0.001). Relative to the Q1, Q3 (model 1 (OR = 1.241, 95% CI [1.114, 1.382], P < 0.001), model 2 (OR = 1.192, 95% CI [1.050, 1.353], P = 0.007), model 3 (OR = 1.145, 95% CI [1.002, 1.310], P = 0.047)) and Q4 (model 1 (OR = 1.524, 95% CI [1.341, 1.733], P < 0.0001), model 2 (OR = 1.422, 95% CI [1.233, 1.640], P < 0.0001), model 3 (OR = 1.333, 95% CI [1.149, 1.547], P < 0.001)) all showed a significant positive correlation between them. The area under the receiver-operating characteristic curve (AUC) for WWI is 0.5447536, the AUC for BMI is 0.5466724, and the AUC for WC and weight is 0.5501341 and 0.5376615, respectively.

CONCLUSIONS

This cross-sectional study revealed a significant positive association between WWI and LBP, but WWI did not show better predictive efficacy than BMI and WC.

Surgical vs. non-surgical management of cervical spine fractures associated with ankylosing spinal disorders: a matched retrospective comparison assessing mortality

BACKGROUND

Ankylosing spinal disorders (ASD) increase the risk of unstable cervical spine fractures, posing a significant mortality risk. Surgery is recommended for patients with neurological deficits, but the effectiveness of non-surgical treatment in those without deficits remains unclear. This study aimed to compare survival rates between surgical and non-surgical treatments of ASD-related cervical fractures in a matched cohort.

METHODS

The study analyzed data from the Swedish Fracture Registry (SFR) on adult patients treated for ASD-related cervical spine fractures between January 2015 and December 2021. Preoperative variables included age, sex, trauma type, neurological function, fracture morphology, and treatment method. Propensity score matching was conducted to compare outcomes between treatment groups, ensuring balanced comparison groups regarding age, sex, type of trauma, time from injury to admission, fracture type, level of injury, and neurological function.

RESULTS

In total, 357 adult patients with ASD-related cervical spine fractures were analyzed. Among them, 186 were treated surgically and 171 non-surgically. Treatment failure and conversion so surgical treatment was seen in 3.4% of the non-surgically treated patients. Most patients were male (80%), with a median age of 75 years. Fractures were mainly caused by low-energy trauma (69%). Most patients (92%) were ambulatory (Frankel grade D or E). In the unmatched analysis, surgically treated patients had significantly lower 1-year mortality rates (13% vs. 22%; p < 0.001), but after matching, there were no longer any difference between the two groups (16% vs. 22%; p = 0.44). These findings were also validated on Kaplan-Meier analysis. Multivariable logistic regression analysis identified high age as the only predictor for 30-day mortality (OR 1.14 [95% CI 1.09-1.22], p < 0.001).

CONCLUSION

Following propensity score matching, surgical and conservative management result in similar mortality outcomes for neurologically intact patients with ASD fractures. Age, rather than treatment approach, emerged as a stronger predictor of overall mortality. Nonetheless, treatment decisions should also consider other clinical outcomes beyond mortality, emphasizing the need for an individualized approach until more robust evidence is available.

Converting an HLA-B27 flow assay from the BD FACSCanto to the BD FACSLyric

HLA-B27 is a major histocompatibility complex (MHC) class I antigen which exhibits strong association (90%) with ankylosing spondylitis. HLA-B27 detection in patients by flow cytometry is a widely used clinical test, performed on many different flow cytometer models. We sought to develop and validate a test conversion protocol for the HLA-B27 test performed on the BD FACSCanto to BD's newer FACSLyric flow cytometers. The development and validation experiments were performed using anti-HLA-B27*FITC/CD3*PE antibody-stained whole blood patient specimens. The anti-HLA-B27*FITC logarithmic median fluorescence (LMF) results on the BD FACSCanto were converted to median fluorescence intensity (MFI) values on the BD FACSLyric. Clustering of the HLA-B27 positive and negative values, using a 3rd order polynomial equation, resulted in a conversion of the BD FACSCanto cutoff values, negative (<150 LMF) and positive (≥160 LMF), to negative (<4530 MFI) and positive (≥6950 MFI) on the BD FACSLyric. Accuracy was assessed by comparing the flow results obtained on the BD FACSCanto and BD FACSLyric to a molecular PCR based assay. Additional validation parameters (compensation verification, intra- and inter-assay precision, and instrument comparison) were performed per the recommendations outlined in the Clinical and Laboratory Standards Institute (CLSI) H62 guidelines for validation of flow cytometry assays.

Risk factor analysis of vertebral fractures requiring surgery in patients with ankylosing spondylitis

OBJECTIVES

This study aimed to determine the risk factors for vertebral fractures requiring surgery in patients with ankylosing spondylitis (AS).

METHODS

We included 60 patients with AS diagnosed by using the modified New York criteria and who were treated in our department from April 2004 to March 2019. We evaluated age, sex, disease duration, C-reactive protein, erythrocyte sedimentation rate, ankylosed sacroiliac joint, bamboo spine, number of ankylosed vertebrae, and treatment (nonsteroidal anti-inflammatory drugs, prednisolone, conventional synthetic disease-modifying antirheumatic drugs, biological disease-modifying antirheumatic drugs, and spine surgery for vertebral fracture) at the final follow-up of the nonsurgical group and the preoperative follow-up of the surgical group.

RESULTS

At the final follow-up, the mean age was 49 years, 46 patients (75%) were male, and the mean disease duration was 27 years. Additionally, 8 (13.3%) and 43 patients (71%) underwent surgical and medical treatments, respectively. The group of surgery for vertebral fracture had significantly higher C-reactive protein levels, which was also significantly associated with vertebral fracture surgery by multivariate analysis.

CONCLUSIONS

C-reactive protein was identified as a risk factor for vertebral fractures requiring surgery. Control of systemic inflammation in patients with AS may reduce the risk of vertebral fractures requiring surgery.

The incidence and prevalence of ankylosing spondylitis in Thailand using ministry of public health database

Ankylosing spondylitis (AS), an inflammatory condition affecting axial and peripheral joints, exhibits varying prevalence worldwide. This study sought to ascertain AS incidence and prevalence in Thailand from 2017 to 2020. Utilizing national databases, individuals aged 18 and above with primary AS diagnoses (ICD-10 code M45) were identified. AS prevalence and incidence were calculated with 95% confidence intervals. The total number of AS patients was 13,292 patients in 2017. The prevalence of AS was 20.4 per 100,000 populations (95% CI 20.0-20.7) in 2017. The number of new AS cases, identified during 2018-2020, was 6784, 6805, and 6791 patients, respectively. The incidences of AS in 2018, 2019, and 2020 were comparable with the incidence of 10.4 (95% CI 10.1-10.6) per 100,000-person-years. The peak age at diagnosis was 50-59 years of age between 2018 and 2020. The number of female patients was 57.8%, 57.0%, and 57.6%, in 2018, 2019, and 2020, respectively. In conclusion, AS was relatively rare among Thais and comparable between males and females. The prevalence and incidence of AS in Thailand were identified by the Thailand Database Ministry of Public Health. The epidemiological profile of AS in Thailand might help to plan better care, workforce needs, and public health budgets.

Do physical therapists follow evidence-based practices for treatment of inflammatory arthritis? Results from an online survey

BACKGROUND

Physical therapists (PTs) should know how to best treat patients with inflammatory arthritis.

OBJECTIVE

To document interventions chosen by PTs for patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS) and whether choices follow evidence-based practice.

METHODS

Licensed musculoskeletal PTs in Quebec, Canada responded to an online survey. Descriptive statistics illustrated proportions for each treatment choice and inferential statistics explored associations with demographic and practice-related factors.

RESULTS

There were 298 PTs who responded to the survey. For both RA and AS respectively, most common interventions were mobility exercises (91.0%; 98.3%) and patient education (90.1%; 92.8%). For both cases, slightly >60% selected strengthening exercises. Passive forms of therapy were chosen by 36% of PTs for RA and 58% for AS. Aerobic exercise was rarely selected. PTs working in the public sector were less likely to use manual therapy for both RA (Odds Ratio (OR) 0.43, 95% confidence interval (CI) 0.22,0.86) and AS (OR 0.46, 95% CI 0.22,0.97).

CONCLUSIONS

Most PTs chose mobility exercises and patient education, representing evidence-based approaches. Despite current recommendations, strengthening and especially aerobic exercises were not used as much. There is a need to increase awareness regarding the benefits of strengthening and aerobic exercise for these patients.

Aryl hydrocarbon receptor gene expression in ankylosing spondylitis and its correlation with interleukin-17, RAR-related orphan receptor gamma t expression, and disease activity indices

Objectives

Considering the role of T helper (Th)17 cells in the pathogenesis of ankylosing spondylitis (AS), the aim of this study was to determine the correlation between aryl hydrocarbon receptor (AHR) gene expression and the expression of Th17-related genes including interleukin (IL)-17 and RAR-related orphan receptor gamma t (RORγt) transcription factor.

Patients and methods

Thirty patients with AS (26 males, 4 females; mean age: 36.1±8.1 years) and 30 age- and sex-matched healthy individuals (26 males, 4 females; mean age: 36.2±14.6 years) were recruited for the case-control study between June 2021 and January 2022. Ribonucleic acid (RNA) was extracted from peripheral blood cells and expression levels of AHR, IL-17, RORγt, and AHR repressor (AHRR) genes were evaluated using real-time polymerase chain reaction technique. The serum level of IL-17 was evaluated with enzyme-linked immunosorbent assay.

Results

The results showed a nonsignificant elevation of AHR, IL-17, and RORγt gene expression in the patient group compared to the control. There was a direct correlation between AHR gene expression and IL-17 and RORγt genes and a negative correlation between AHR and AHRR expression. Moreover, AHR gene expression showed a weak correlation with disease activity indices, including Bath Ankylosing Spondylitis Disease Activity Index, Bath Ankylosing Spondylitis Functional Index, Bath Ankylosing Spondylitis Metrology Index, Bath Ankylosing Spondylitis Global Score, and Ankylosing Spondylitis Quality of Life. Moreover, the serum level of IL-17 was higher in AS patients compared to the healthy group (p=0.02).

Conclusion

Upregulated expression of the AHR gene in ankylosing spondylitis and its correlation with IL-17 and ROR-γ t gene expression suggests that it could be a potential diagnostic and therapeutic target for AS.

Effectiveness of bDMARDs in ankylosing spondylitis patients by biologic use: experience from the CorEvitas PsA/SpA Registry

OBJECTIVE

To describe bDMARD initiators by biologic experience among ankylosing spondylitis (AS) patients and change in disease activity and patient-reported outcomes (PROs) in real-world US patients.

METHODS

We included patients ≥18 years with AS based on physician diagnosis enrolled between 3/2013 and 11/2019 in the CorEvitas Psoriatic Arthritis (PSA)/Spondyloarthritis Registry (NCT02530268). Patients concurrently diagnosed with PSA were excluded. Baseline (bDMARD initiation) demographics, comorbidities, disease characteristics, treatment, and PROs were collected. Response rates and changes in disease activity and PROs between baseline and 6- and 12- month follow-up visits were calculated.

RESULTS

Of the 489 AS patients in the PsA/SpA Registry, 254 AS (52.0%) patients initiated a bDMARD at enrollment or during follow-up (total initiations: AS = 313). Of the 313 AS initiations, 179 (57.2%) had a 6-month follow-up, 122 (39.0%) had a 12-month follow-up, and 94 (30.0%) had a 6- and 12-month follow-up visit. For those AS initiators with a 6-month follow-up, the mean age was 49.1 years, 44.4% were female, and 70.4%, 47.5%, 96.1%, and 46.9% had never used cDMARDs, TNFis, non-TNFis, and bDMARDs, respectively. Of these 179 AS initiators, 20.1% and 14.0% achieved ASAS20/40, respectively. Further, only 34% achieved low disease activity (ASDAS <2.1). When stratified by biologic-naivete and biologic-experience, the ASAS 20/40 achievement rates were 26.2% and 14.7%, and 21.4% and 7.4%, respectively, for this cohort.

CONCLUSION

Although AS patients initiate bDMARDs, many do not achieve optimal treatment responses. Future research is needed to investigate the aspects associated with inadequate improvement and treatment response to bDMARDs.

Spondyloarthropathies That Mimic Ankylosing Spondylitis: A Narrative Review

Ankylosing spondylitis is the most common type of seronegative inflammatory spondyloarthropathy often presenting with low back or neck pain, stiffness, kyphosis and fractures that are initially missed on presentation; however, there are other spondyloarthropathies that may present similarly making it a challenge to establish the correct diagnosis. Here, we will highlight the similarities and unique features of the epidemiology, pathophysiology, presentation, radiographic findings, and management of seronegative inflammatory and metabolic spondyloarthropathies as they affect the axial skeleton and mimic ankylosing spondylitis. Seronegative inflammatory spondyloarthropathies such as psoriatic arthritis, reactive arthritis, noninflammatory spondyloarthropathies such as diffuse idiopathic skeletal hyperostosis, and ochronotic arthritis resulting from alkaptonuria can affect the axial skeleton and present with symptoms similar those of ankylosing spondylitis. These similarities can create a challenge for providers as they attempt to identify a patient's condition. However, there are characteristic radiographic findings and laboratory tests that may help in the differential diagnosis. Axial presentations of seronegative inflammatory, non-inflammatory, and metabolic spondyloarthropathies occur more often than previously thought. Identification of their associated symptoms and radiographic findings are imperative to effectively diagnose and properly manage patients with these diseases.

Adverse events of tumor necrosis factor alpha inhibitors for the treatment of ankylosing spondylitis: A meta-analysis of randomized, placebo-controlled trials

Objective: Tumor necrosis factor alpha inhibitors (TNFi) have shown substantial efficacy in alleviating and treating ankylosing spondylitis (AS). However, the heightened interest is accompanied by concerns over adverse events. In this meta-analysis, we analyzed both serious and common adverse events in patients treated with tumor necrosis factor alpha inhibitors compared with those in the placebo group. Methods: We searched for clinical trials in PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, Wanfang Data, and VIP Data. Studies were selected based on strict inclusion and exclusion criteria. Only randomized, placebo-controlled trials were included in the final analysis. RevMan 5.4 software was used for performing meta-analyses. Results: A total of 18 randomized controlled trials recruiting 3,564 patients with ankylosing spondylitis were included, with overall moderate to high methodological quality. Compared with the placebo group, the incidences showed no difference and were only slightly increased numerically for serious adverse events, serious infections, upper respiratory tract infection, and malignancies in patients treated with tumor necrosis factor alpha inhibitors. However, tumor necrosis factor alpha inhibitor treatment significantly increased the incidence of overall adverse events, nasopharyngitis, headache, and injection-site reactions in ankylosing spondylitis patients when compared with placebo. Conclusion: The available data indicated that ankylosing spondylitis patients who received tumor necrosis factor alpha inhibitors had no significantly increased risks of serious adverse events when compared with the placebo group. However, tumor necrosis factor alpha inhibitors significantly increased the incidence rate of common adverse events, including nasopharyngitis, headache, and injection-site reactions. Large-scale and long-term follow-up clinical trials are still necessary to further investigate the safety of tumor necrosis factor alpha inhibitors in ankylosing spondylitis treatment.

Genetically supported causality between gut microbiota, gut metabolites and low back pain: a two-sample Mendelian randomization study

Background

Previous studies have implicated a vital association between gut microbiota/gut microbial metabolites and low back pain (LBP), but their causal relationship is still unclear. Therefore, we aim to comprehensively investigate their causal relationship and identify the effect of gut microbiota/gut microbial metabolites on risk of LBP using a two-sample Mendelian randomization (MR) study.

Methods

Summary data from genome-wide association studies (GWAS) of gut microbiota (18,340 participants), gut microbial metabolites (2,076 participants) and LBP (FinnGen biobank) were separately obtained. The inverse variance-weighted (IVW) method was used as the main MR analysis. Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) and MR-Egger regression were conducted to evaluate the horizontal pleiotropy and to eliminate outlier single-nucleotide polymorphisms (SNPs). Cochran's Q-test was applied for heterogeneity detection. Besides, leave-one-out analysis was conducted to determine whether the causal association signals were driven by any single SNP. Finally, a reverse MR was performed to evaluate the possibility of reverse causation.

Results

We discovered that 20 gut microbial taxa and 2 gut microbial metabolites were causally related to LBP (p < 0.05). Among them, the lower level of family Ruminococcaceae (OR: 0.771, 95% CI: 0.652-0.913, FDR-corrected p = 0.045) and Lactobacillaceae (OR: 0.875, 95% CI: 0.801-0.955, FDR-corrected p = 0.045) retained a strong causal relationship with higher risk of LBP after the Benjamini-Hochberg Corrected test. The Cochrane's Q test revealed no Heterogeneity (p > 0.05). Besides, MR-Egger and MR-PRESSO tests showed no significant horizontal pleiotropy (p > 0.05). Furthermore, leave-one-out analysis confirmed the robustness of MR results. After adding BMI to the multivariate MR analysis, the 17 gut microbial taxa exposure-outcome effect were significantly attenuated and tended to be null.

Conclusion

Our findings confirm the the potential causal effect of specific gut microbiota and gut microbial metabolites on LBP, which offers new insights into the gut microbiota-mediated mechanism of LBP and provides the theoretical basis for further explorations of targeted prevention strategies.

Identifying inadequate response among patients with ankylosing spondylitis and psoriatic arthritis prescribed advanced therapy in a real-world, commercially insured adult population in the USA

OBJECTIVE

This study aimed to assess treatment patterns and frequency of inadequate response associated with advanced therapy initiation among patients with ankylosing spondylitis (AS) and psoriatic arthritis (PsA) in the USA.

METHODS

Adult patients with AS or PsA who initiated advanced therapy were identified from the HealthCore Integrated Research Database®. Inadequate response to advanced therapies (tumour necrosis factor inhibitors [TNFi] and non-TNFi biologics) was identified using a claims-based algorithm. Factors influencing inadequate response were assessed using multivariable logistic regression.

RESULTS

In total, 646 patients with AS, and 1433 patients with PsA were evaluated. Among patients with AS (mean age, 43 years; male, 58%), 93% patients initiated TNFi, and 69% of patients had inadequate response. In patients with PsA (mean age, 49 years; male, 47%), 67% initiated TNFi, and 77% had inadequate response. Low adherence was the main predictor of inadequate response in patients with AS (56%) and PsA (63%). Inadequate responders were more likely to be female (odds ratio [OR] 2.05 for AS and 1.37 for PsA). Prior exposure to TNFi was associated with 3.89- and 2.14-fold greater odds of inadequate response in both AS and PsA patients, respectively, while patients using methotrexate were less likely to have inadequate response (OR 0.48 for AS and 0.72 for PsA; all p < 0.05).

CONCLUSIONS

Over 69% of patients with AS and 77% of patients with PsA had inadequate response to their index advanced therapy during 1 year after initiation. Health plan claims data appear useful to classify inadequate responders in AS and PsA. Key Points • Estimating inadequate response to advanced therapies and identifying factors associated with this outcome using claims data could improve treatment outcomes in AS and PsA. • In a sample of commercially insured US patients, over 69% of patients with AS and 77% of patients with PsA had inadequate response to their index advanced therapy during 1 year after initiation. Patient characteristics such as sex and prior therapy use were predictive of inadequate response to advanced therapies. • Health plan claims data appear useful to classify inadequate responders in AS and PsA and identify factors associated with this outcome.

Spinal cord injury and spinal fracture in patients with ankylosing spondylitis

Background

Spinal cord injury (SCI) and spinal fracture are major complications in patients with ankylosing spondylitis (AS) who sustain spinal trauma. The purpose of this study was to investigate the incidence, predictors, and sequelae of spinal trauma in patients with AS.

Methods

This retrospective study included patients with AS who were admitted for spinal trauma between January 1, 2006, and June 30, 2016. The study compared clinical outcomes of patients between group 1: SCI alone, group 2: spinal fracture alone (no SCI), and group 3: both SCI and spinal fracture.

Results

Of the 6285 patients with AS admitted during the retrospective study period, only 105 suffered from spinal trauma and were enrolled in the study. Case number in group 1, 2, and 3 was 11(10.48%), 45(42.85%), and 49(46.67%), respectively. Among the patients with spinal fractures, 52.1% had SCI. Bamboo spine was significantly more prevalent in the fracture group than in the nonfracture group (78.7% vs. 36.4%; P = 0.006). Patients with SCI had more instances of subluxation or dislocation (48.3% vs. 8.9%; P < 0.001) and more cases of spinal epidural hematoma (SEH; 21.7% vs. 2.2%; P = 0.003) than patients without SCI. The rate of delayed diagnosis for spinal fracture was 31.4%, with one-third of patients developing delayed SCI. Among the patients with incomplete SCI, 58.3% achieved neurological improvement after treatment (P = 0.004).

Conclusions

Patients with AS and bamboo spine at radiograph had a higher rate of spinal fracture, which may be an important factor in SCI in patients with AS. Spinal fractures involving the C3–C7 region, subluxation or dislocation, severe spinal fracture, and SEH were found to be predictive of SCI, and SCI in patients with AS resulted in higher mortality and complication rates.

Impact of HLA-B27 and Disease Status on the Gut Microbiome of the Offspring of Ankylosing Spondylitis Patients

Multiple studies have shown the microbiota to be abnormal in patients with spondyloarthritis (SpA). The purpose of this study was to explore the genetic contributions of these microbiota abnormalities. We analyzed the impact of HLA-B27 on the microbiota of children at risk for SpA and compared the microbiota of HLA-B27+ pediatric offspring of ankylosing spondylitis (AS) patients with that of HLA-B27+ children with SpA. Human DNA was obtained from the offspring for determination of HLA-B27 status and polygenic risk score (PRS). Fecal specimens were collected from both groups for sequencing of the V4 region of the 16S ribosomal RNA gene. Among the offspring of AS patients, there was slight clustering by HLA-B27 status. After adjusting for multiple comparisons, five operational taxonomic units (OTUs) representing three unique taxa distinguished the HLA-B27+ from negative children: Blautia and Coprococcus were lower in the HLA-B27+ offspring, while Faecalibacterium prausnitzii was higher. HLA-B27+ offspring without arthritis were compared to children with treatment-naïve HLA-B27+ SpA. After adjustments, clustering by diagnosis was present. A total of 21 OTUs were significantly associated with diagnosis state, including Bacteroides (higher in SpA patients) and F. prausnitzii (higher in controls). Thus, our data confirmed associations with B. fragilis and F. prausnitzii with juvenile SpA, and also suggest that the mechanism by which HLA-B27 is associated with SpA may not involve alterations of the microbiota.

Prevalence of sacroiliitis among patients referred for hip MR arthrography

OBJECTIVE

To determine the prevalence of sacroiliitis among patients who have been referred for MR arthrography.

MATERIALS AND METHODS

A retrospective search identified 130 consecutive MR arthrograms of the hip performed on a 1.5T Siemens Avanto at our institution from August 2013 to August 2014. Four studies were excluded due to the absence of a coronal short tau inversion recovery sequence of the pelvis, leaving 126 studies for analysis. A musculoskeletal radiology fellow and three attending musculoskeletal radiologists reviewed the images for the presence of bone marrow edema affecting the sacroiliac joints. Only cases of bone marrow edema meeting the Assessment of SpondyloArthritis international Society definition were considered positive. The two-tailed Fisher's exact test was used to compare the prevalence of positive MRI findings among age and gender groups. GraphPad InStat (GraphPad Software) was used for statistical calculations.

RESULTS

Patients less than 40 years of age demonstrated a statistically higher prevalence of positive MRI findings of sacroiliitis when compared to patients older than 40 (p = 0.0082). No difference in prevalence was found between genders. Overall prevalence of MRI signal alteration suggestive of sacroiliitis as defined by the Assessment of SpondyloArthritis international Society was 4.8%. Among the six patients with positive findings, two were subsequently diagnosed with spondyloarthritis.

CONCLUSION

Hip pain may be a presenting symptom of spondyloarthritis and attention should be paid to the sacroiliac joints during screening examinations, particularly in patients less than 40 years of age.

Does Gender Impact a Diagnosis of Ankylosing Spondylitis?

Objective

The study objective was to explore differences in ankylosing spondylitis (AS) diagnosis experiences between men and women by examining the coding of health events over the 2 years preceding AS diagnosis.

Methods

Claims data (January 2006–April 2019) from the MarketScan databases were examined. Patients who had received two or more AS diagnoses at least 30 days apart and had at least 2 years of insurance enrollment before their first AS diagnosis were analyzed. Men were matched 1:1 to women by age, diagnosis date, insurance type, and enrollment duration. Health events (diagnosis and provider codes) were examined over 2 years before AS diagnosis and stratified by gender. Data were analyzed using univariate χ² tests.

Results

Among 7744 patients, 274 of 1906 AS‐related codes showed statistically significant differences between men and women. Women received more diagnosis codes than men across diagnoses and providers; the largest difference in diagnosis codes among women versus men was in peripheral symptom coding (57.7% vs. 43.9%, respectively). More women than men received diagnosis codes for depression (21.2% vs. 9.8%) and other musculoskeletal symptoms (52.8% vs. 40.0%); only gout was more common in men (6.5%) than in women (2.2%). Among men, backache codes gradually increased 12 months before AS diagnosis, whereas axial and sacroiliitis coding increased sharply immediately before diagnosis. The greatest difference in physician types visited was for rheumatologists: 64.2% of women had visits compared with 45.1% of men.

Conclusion

Further investigation into the dissimilarities in diagnostic experiences between men and women is needed to determine whether differences are due to disease phenotype or potential cognitive bias influencing diagnostic decision‐making.

A Road Map of the Axial Spondyloarthritis Continuum

Axial spondyloarthritis (axSpA) is a chronic, immune-mediated inflammatory disease characterized by inflammatory low back pain, inflammation in peripheral joints and entheses, and other extra-articular or systemic manifestations. Although our understanding of the natural history of axSpA has been limited by incomplete knowledge of disease pathogenesis, axSpA is increasingly understood as a spectrum of axial, peripheral, and extra-articular inflammatory conditions that includes nonradiographic axSpA and radiographic axSpA, also known as ankylosing spondylitis. In this narrative review, we present a road map of this axSpA continuum, highlighting genetic risk factors for the development of axSpA, triggers of disease, and reasons for and implications of diagnostic delay. We present a detailed overview of the spectrum of axSpA clinical manifestations and highlight factors known to influence the risk of disease progression. Finally, we provide some expert commentary on the practical use of this road map to assist health care providers in the identification of axSpA in clinical practice.

Impact of age on mortality and complications in patients with Ankylosing Spondylitis spine fractures

OBJECTIVE

The aim of this retrospective cohort study was to study the impact of age on in-hospital complications and mortality following surgery for Ankylosing Spondylitis (AS) associated spine fractures.

METHODS

We extracted data from the Nationwide Inpatient Sample (NIS) database (1998-2018) using ICD-9/10 codes. Patients with a primary diagnosis of AS associated spine fractures who underwent fusion surgery were included. Complications and in-hospital mortality were analyzed.

RESULTS

A total cohort of 8526 patients was identified. Overall, the median age of the cohort was 69 years. AS associated fractures were equally distributed among cervical and thoracolumbar regions. Overall, complications were noted in 48% of patients and pulmonary complications were the most common (32%) followed by renal (13%) and infection (12%). Complications were seen in 57.3% of patients ≥ 70 years of age compared to 38.4% of patients < 70 years of age (p < .0001). Also, 9.9 % of patients ≥ 70 years of age had in-hospital mortality compared to 3.1 % of patients < 70 years of age (p < .0001). Based on surgical approaches, elderly patients (≥70 years) who underwent anterior, posterior, and anterior + posterior approaches had 19.8%, 7.4% and 16.4% in-hospital mortality compared to 5.3%, 2.2% and 7.4% respectively for patients < 70 years.

CONCLUSIONS

Elderly patients (≥70 years of age) were 3.2 times more likely to have in-hospital mortality and higher complications compared to younger patients (57% vs. 38%). Cervical compared to thoracolumbar fractures and anterior compared to posterior surgical approaches were associated with higher complications and in-hospital mortality.

Geographic Variations in Diagnosis and Treatment of Ankylosing Spondylitis in the United States: A Real-World Study

Introduction

Diagnosis difficulties are common for ankylosing spondylitis (AS) patients, leading to inadequate and inconsistent treatment. We evaluated the national and geographic variability in disease diagnosis and treatment in the United States.

Methods

This retrospective, cross-sectional analysis utilized the IBM® MarketScan® Administrative Claims Database from 2014 to 2019. AS patients ≥ 18 years of age with continuous medical and pharmacy enrollment during the calendar year and complete geographic information during the study period were included. Patient cohorts assessed were D1 (≥ 1 AS diagnoses within each calendar year of assessment between 2014 and 2019), D2 (≥ 2 non-rheumatologist AS diagnoses), and D3 (≥ 2 rheumatologist AS diagnoses). For D2 and D3, diagnoses were ≥ 6 months apart, but within 18 months. Annual AS diagnostic prevalence and treatment rates were determined from 2014 to 2019 nationally and per state in 2019. Treatments assessed were disease-modifying antirheumatic drugs (DMARDs), opioids, nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, and methotrexate.

Results

Nationally, AS diagnostic prevalence increased from 2014 to 2019, with 2019 rates of 9.6 (D1), 5.1 (D2), and 3.5 (D3) per 10,000 persons. Diagnostic prevalence varied between states, which was not explained by age, sex, racial distribution, or rheumatologists per capita. Nationally, a greater percentage of D3 patients vs. D1 and D2 patients received biologic/targeted synthetic DMARDs (bDMARD/tsDMARDs) and conventional synthetic DMARD. Opioid use ranged from 37 to 40% in 2019 and decreased from 2014 for all cohorts. Corticosteroid and methotrexate use decreased slightly, while NSAID and bDMARD/tsDMARD use generally increased from 2014 to 2019.

Conclusions

AS diagnostic prevalence is increasing nationally, though it remains low among some states. bDMARD/tsDMARDs use was more common among patients treated by rheumatologists. Opioid and corticosteroid use is decreasing, though national rates remain high with significant state variability. Further education is needed, particularly in states with low prevalence and inadequate treatment, to improve diagnosis and treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40744-021-00406-9.

Racial Differences in Prevalence and Treatment for Psoriatic Arthritis and Ankylosing Spondylitis by Insurance Coverage in the USA

INTRODUCTION

Patients with psoriatic arthritis (PsA) and ankylosing spondylitis (AS) may receive suboptimal care, and differences in care by race/ethnicity, sex, and insurance coverage are not well studied.

METHODS

This was a descriptive, retrospective cross-sectional US claims database analysis utilizing the Medicaid multi-state segment of the IBM® MarketScan® Commercial Claims and Encounters Supplemental Database and Optum Insight Clinformatics® Data Mart database for 2019. Patients aged ≥ 18 years with PsA or AS and continuous medical and pharmacy coverage were included. Outcomes evaluated were prevalence and percentage of patients receiving biologic disease-modifying antirheumatic drugs (bDMARDs)/targeted synthetic DMARDs (tsDMARDs) or visiting a rheumatologist. Outcomes were stratified by race/ethnicity, sex, and insurance coverage, with outcomes determined for commercial insurance, Medicare, and Medicaid enrollees. Differences observed in outcomes were numerical in nature.

RESULTS

Prevalences of PsA and AS were highest for Medicare enrollees (320 and 156 per 100,000 persons [0.32 and 0.16%], respectively) and lowest for Medicaid enrollees (132 and 71 per 100,000 persons [0.13 and 0.07%], respectively). White patients had the greatest prevalence versus patients of other races/ethnicities. Females had a higher prevalence of PsA than males, while AS prevalence was generally lower for females versus males for each insurance category. The percentage of patients prescribed bDMARDs/tsDMARDs was highest for commercial insurance enrollees (PsA 63%, AS 43%) and lowest for Medicare enrollees (PsA 21%, AS 11%). The proportion of patients who saw a rheumatologist was lower for Medicaid enrollees (PsA 12%, AS 10%) than for commercial insurance or Medicare enrollees (PsA 68%, 55%; AS 67%, 42%). For commercial insurance and Medicare enrollees, the percentage of patients visiting a rheumatologist was similar by race/ethnicity but higher for females versus males.

CONCLUSIONS

The prevalence and treatment of PsA and AS differs by race/ethnicity, insurance coverage, and sex in the USA. Efforts for improving access to care are needed to improve outcomes among all patients.

Clinical Manifestations and Diagnosis of Axial Spondyloarthritis

BACKGROUND

Axial spondyloarthritis (axSpA) is a chronic, rheumatic disease characterized by inflammation of the sacroiliac joint, spine, and entheses. Axial spondyloarthritis affects up to 1.4% of adults in the United States and is associated with decreased quality of life, increased mortality, and substantial health care-related costs, imposing a high burden on patients, their caregivers, and society.

SUMMARY OF WORK

Diagnosing axSpA can be difficult. In this review, we seek to help rheumatologists in recognizing and diagnosing axSpA.

MAJOR CONCLUSIONS

A discussion of challenges associated with diagnosis is presented, including use and interpretation of imaging, reasons for diagnostic delays, differences in disease presentation by sex, and differential diagnoses of axSpA.

FUTURE RESEARCH DIRECTIONS

The early diagnosis of axSpA and advances in available therapeutic options have improved patient care and disease management, but delays in diagnosis and treatment remain common. Additional research and education are critical for recognizing diverse axSpA presentations and optimizing management early in the course of disease.

Update on Juvenile Spondyloarthritis

Spondyloarthritis (SpA) is a blanket term encompassing entities such as enthesitis-related arthritis, nonradiographic axial SpA, and ankylosing spondylitis. These diseases share many clinical features, including a predilection for inflammation of the entheses and the sacroiliac joints. The nomenclature is based on the evolution of the classification of the disease and the age of the patient. SpA has a prevalence of approximately 1% of the population of the United States, with 10% to 20% of patients experiencing the onset during childhood. Children with onset of arthritis before age 16 years are classified as having juvenile idiopathic arthritis. Children with enthesitis and/or sacroiliitis are further classified as belonging to the enthesitis-related arthritis subtype of juvenile idiopathic arthritis. The initial manifestations can be subtle and will usually include a peripheral pattern of arthritis and enthesitis. It may take several years for axial disease to develop in children. Except for an association with the human leukocyte antigen (HLA-B27) serotype, there are no laboratory markers for the disease, and the radiographic findings are often negative. A careful clinical evaluation for evidence of inflammation in the entheses and the joints and a search for comorbidities are required. Magnetic resonance imaging facilitates the early detection of sacroiliitis, an important feature that may be clinically silent. Because recent studies indicate that earlier introduction of therapy can help achieve better outcomes, rapid identification and treatment of children with SpA is essential.

Cementless total hip arthroplasty for three different degrees of hip involved secondary to ankylosing spondylitis: an analysis of 195 hips

Background

Hip involved secondary to ankylosis spondylitis (AS) had a huge influence on hip function. Cementless total hip arthroplasty (THA) can improve hip function. However, no previous study compared the outcomes of THA for AS patients with three different degrees of hip involvement.

Methods

The 195 hips were retrospectively analyzed and divided into non-ankylosed group (group A, 94 hips), fibrous ankylosed group (group B, 49 hips), and bony ankylosed group (group C, 52 hips). postoperative range of motion (ROM), harris hip scores (HHS), the short-form 12 health survey (SF-12), length of stay (LOS), cost, radiological assessments, and complications were compared.

Results

The follow-up time was (79.4 ± 29.5) months for group A, (80.6 ± 28.9) months for group B, and (79.1 ± 28.9) months for group C (P = 0.966). Group A had the best postoperative hip ROM (P < 0.001), while group A and B can realize better HHS than group C (P < 0.001). The three groups had similar SF-12 postoperatively. For group A, LOS and cost for unilateral procedure were the least than that for group B and C (P = 0.003 and P = 0.001). Similar radiological assessments were achieved for three groups. 1 hip in group A encountered delay union of wound. 1 hip in group C encountered delay union of wound and dislocation and another patient encountered femoral fracture intraoperatively. 12 hips (12.8%) in group A, 6 hips (12.2%) in group B, and 6 hips (11.5%) in group C encountered asymptomatic heterotopic ossification (P = 0.977).

Conclusion

For AS patients with hip involvement, THA can improve hip ROM and function. THA for the non-ankylosed hip can realize the better hip function and postoperative ROM than ankylosed hip.

'Can you touch your toes?' spondyloarthropathies and acute anterior uveitis for primary eyecare practitioners

The rheumatological diseases known as spondyloarthropathies (SpAs) are reviewed with respect to the current classifications of SpAs and from the perspective of ophthalmic practitioners. The focus is on the most common spondyloarthropathy, ankylosing spondylitis (AS), and the key symptoms, such as inflammatory back pain. The association with HLA-B27 and acute anterior uveitis (AAU) and the major clinical considerations for primary eye care practitioners are reviewed. An atypical case study illustrates difficulties in the detection and diagnosis of ankylosing spondylitis.

Low back pain

Low back pain covers a spectrum of different types of pain (eg, nociceptive, neuropathic and nociplastic, or non-specific) that frequently overlap. The elements comprising the lumbar spine (eg, soft tissue, vertebrae, zygapophyseal and sacroiliac joints, intervertebral discs, and neurovascular structures) are prone to different stressors, and each of these, alone or in combination, can contribute to low back pain. Due to numerous factors related to low back pain, and the low specificity of imaging and diagnostic injections, diagnostic methods for this condition continue to be a subject of controversy. The biopsychosocial model posits low back pain to be a dynamic interaction between social, psychological, and biological factors that can both predispose to and result from injury, and should be considered when devising interdisciplinary treatment plans. Prevention of low back pain is recognised as a pivotal challenge in high-risk populations to help tackle high health-care costs related to therapy and rehabilitation. To a large extent, therapy depends on pain classification, and usually starts with self-care and pharmacotherapy in combination with non-pharmacological methods, such as physical therapies and psychological treatments in appropriate patients. For refractory low back pain, a wide range of non-surgical (eg, epidural steroid injections and spinal cord stimulation for neuropathic pain, and radiofrequency ablation and intra-articular steroid injections for mechanical pain) and surgical (eg, decompression for neuropathic pain, disc replacement, and fusion for mechanical causes) treatment options are available in carefully selected patients. Most treatment options address only single, solitary causes and given the complex nature of low back pain, a multimodal interdisciplinary approach is necessary. Although globally recognised as an important health and socioeconomic challenge with an expected increase in prevalence, low back pain continues to have tremendous potential for improvement in both diagnostic and therapeutic aspects. Future research on low back pain should focus on improving the accuracy and objectivity of diagnostic assessments, and devising treatment algorithms that consider unique biological, psychological, and social factors. High-quality comparative-effectiveness and randomised controlled trials with longer follow-up periods that aim to establish the efficacy and cost-effectiveness of low back pain management are warranted.

Educational needs and challenges in axial spondyloarthritis

PURPOSE OF REVIEW

Axial spondyloarthritis (axSpA) affects 0.5-1% of the population in many regions of the world. This review summarizes the challenges in medical education around axSpA with attention to evidence around delayed diagnosis, clinician familiarity with typical axSpA features, such as inflammatory back pain and adherence to accepted management principles.

RECENT FINDINGS

Clinicians who commonly manage patients with chronic back pain or other typical axSpA features are not consistently aware of the concept of inflammatory back pain and common extra-spinal manifestations. Further, clinicians may not be familiar with the nonradiographic spectrum of axSpA. Management of patients with possible axSpA does not consistently follow principles that would establish an axSpA diagnosis, and diagnosis of axSpA remains delayed by 6-7 years on average, with evidence suggesting management disparities on the basis of sex and race in some cases. Referral recommendations have increased the probability of axSpA diagnosis up to about 40% and, may complement educational efforts in axSpA.

SUMMARY

Educational efforts in axSpA should focus on providing front-line clinicians with a better understanding of inflammatory back pain, the nonradiographic form of axSpA, and accepted principles in axSpA management.

Comparison of Next-Generation Sequencing-Based Human Leukocyte Antigen Typing with Clinical Flow Cytometry and Allele-Specific PCR Melting Assays for HLA-B27 Genotyping

BACKGROUND

Due to the strong association between ankylosing spondylitis and Human Leukocyte Antigen (HLA)-B27, accurate identification of HLA-B27 is important in the diagnosis of patients with suspected spondyloarthritides. For this study, we compared a high-resolution HLA-B typing method to the clinical flow cytometry and allele-specific PCR melting assays to determine clinical benefits of high-resolution testing.

METHODS

Residual clinical samples submitted for HLA-B27 testing by flow cytometry were tested by single-locus HLA-B genotyping using next-generation sequencing (NGS), and PCR with melting curve analysis, currently used as a reflex test for indeterminate flow cytometry results.

RESULTS

Fifty out of the 51 samples (98%) positive by flow cytometry confirmed as HLA-B27 positive by PCR melting assay and by NGS. The sample that did not confirm was genotyped as HLA-B*07:02. All the samples negative by flow cytometry were confirmed as HLA-B27 negative by both PCR melting assay and NGS. For the group that was indeterminate by flow cytometry, 84.5% (n = 49) typed as positive for HLA-B27, while 15.5% (n = 9) were negative for HLA-B27 but positive for HLA-B*07:02. NGS was the only method able to distinguish between pathogenic and nonpathogenic HLA-B27 variants, in contrast to the flow cytometry or the PCR melting assays.

CONCLUSIONS

Single-locus NGS is superior to flow cytometry and PCR melting assay for the unambiguous identification of HLA-B27 variants, and uniquely able to distinguish between pathogenic and nonpathogenic B27 alleles. Due to its high accuracy, it may be a feasible superior alternative to flow cytometry and traditional molecular methods for clinical HLA-B27 testing.

Health care utilization and cost associated with switching biologics within the first year of biologic treatment initiation among patients with ankylosing spondylitis

BACKGROUND

Costs associated with biologic switching and discontinuation can be high in chronic inflammatory diseases. Inappropriate use of medications may have cost implications for both payers and patients. Understanding of biologic utilization and switching rates is lacking among patients with ankylosing spondylitis (AS).

OBJECTIVE

To compare direct costs of treatment switchers, nonswitchers, and discontinuers among patients with AS who newly initiated a biologic.

METHODS

Patients aged ≥ 18 years with an AS diagnosis and ≥ 1 pharmacy claim for an FDA-approved subcutaneous biologic for AS between January 1, 2016, and December 31, 2016 (identification period) were identified from the Truven Health MarketScan Databases. At the time of biologic initiation (index date), eligible patients were continuously enrolled with medical and pharmacy claims for ≥ 1 year before (baseline period) and ≥ 1 year after the index date (follow-up period). Patients with AS were categorized into 3 mutually exclusive groups of nonswitchers (patients who remained on their index biologic), switchers (patients who had a prescription for a biologic therapy other than their index biologic), and discontinuers (patients who had gaps in prescription claims [> 120 days]) based on their biologic utilization pattern during the 1-year follow-up period. Health care costs (inflated to year 2017 costs) during follow-up were described across the 3 groups separately and by disease. Adjusted health care resource utilization and costs during 1-year follow-up were estimated, controlling for age, sex, fulltime work status, and Charlson Comorbidity Index (Deyo's modification) during the baseline period.

RESULTS

A total of 791 patients with AS who were newly initiating a biologic were categorized as switchers (15.4%), nonswitchers (53.1%), and discontinuers (31.5%). Switchers and discontinuers had higher all-cause health care utilization than nonswitchers during the 1-year follow-up period. Switchers had higher mean total health care costs than nonswitchers ($71,280 vs. $66,573) due to increased medical ($13,897 vs. $12,043) and pharmacy costs ($57,384 vs. $54,530). Discontinuers had the lowest total health care costs ($41,179) but had the highest medical costs ($19,079). Adjusted analyses for covariates confirmed similar trends as the unadjusted analysis, where discontinuers had significantly lower total health care and pharmacy costs but had higher medical costs (with increased emergency department and outpatient visits) than nonswitchers (all P < 0.001). Switchers had increased outpatient visits and costs versus nonswitchers in the adjusted analysis (P < 0.001); small sample sizes in the switcher group may have limited the ability to detect significant trends in the adjusted analysis.

CONCLUSIONS

Biologic switching resulted in higher total health care costs than remaining on the same biologic in patients with AS. These findings highlight the clinical and economic impact of discontinuing or switching biologic therapies in patients with AS, which may inform treatment and/or formulary decision making.

DISCLOSURES

This study was sponsored by Novartis Pharmaceuticals (East Hanover, NJ). Yi, Dai, and Park are employed by Novartis. Piao was an employee of KMK Consulting, supporting Novartis at the time of this study; Zheng is an employee of KMK Consulting and works as a consultant for Novartis. Portions of this work were presented at the 2019 AMCP Managed Care and Specialty Pharmacy Annual Meeting; March 25-28, 2019; San Diego, CA; and AMCP Nexus 2019; October 29-November 1, 2019; National Harbor, MD.

Understanding Barriers in the Pathway to Diagnosis of Ankylosing Spondylitis: Results From a US Survey of 1690 Physicians From 10 Specialties

Objective

Early diagnosis of ankylosing spondylitis (AS) remains challenging because of the high prevalence of chronic back pain in patients initially treated by nonrheumatology health care providers (HCPs). We assessed the patient pathway to rheumatology referral, including HCP recognition of inflammatory back pain (IBP) and other features suggestive of AS, diagnostic workup, treatment, and referral to a specialist with the goal of identifying barriers to patient referral to a rheumatologist.

Methods

US HCPs from 10 specialties were invited to participate in a cross‐sectional web‐based survey on clinical characteristics and diagnostic measures leading to IBP suspicion and the subsequent referral process. Eligible HCPs were actively practicing and had referred a patient with suspected IBP or ocular findings (ophthalmology only) within 12 months. Data were analyzed descriptively.

Results

Of 1690 HCPs, 61% identified morning stiffness lasting more than 30 minutes, 29% sleep disturbance due to back pain, and 28% pain that improves with activity as features suggestive of IBP. Nearly two‐thirds of primary care HCPs reported that they were the first HCPs consulted by patients with suspected IBP. Among HCPs ordering diagnostic blood work, approximately 90% selected antinuclear antibody and rheumatoid factor, whereas 76% selected human leukocyte antigen B27. Almost 40% would treat patients with suspected IBP themselves. HCPs cited lack of adequate specialists nearby (35.1%), insurance restrictions (47.1%), and long wait time (77.0%) as barriers to early referral.

Conclusion

Most HCPs had difficulty identifying features suggestive of IBP and indicated insurance restrictions and long wait times as barriers to early referral of patients with potential AS.

Ixekizumab Improves Functioning and Health in the Treatment of Radiographic Axial Spondyloarthritis: Week 52 Results from 2 Pivotal Studies

Objective.

This study evaluated the effect of ixekizumab (IXE) on self-reported functioning and health in patients with radiographic axial spondyloarthritis (r-axSpA) who were either biological disease-modifying antirheumatic drug (bDMARD)–naïve or failed at least 1 tumor necrosis factor inhibitor (TNFi).

Methods.

In 2 multicenter, randomized, double-blind, placebo-controlled, and active-controlled (bDMARD-naïve only) trials, patients with r-axSpA were randomly assigned to receive 80 mg of IXE [every 2 weeks (Q2W) or every 4 weeks (Q4W)], placebo (PBO), or adalimumab (ADA; bDMARD-naïve only). After 16 weeks, patients who received PBO or ADA were rerandomized to receive IXE (Q2W or Q4W) up to Week 52. Functioning and health were measured by the generic 36-item Short Form Health Survey (SF-36) and the disease-specific Assessment of Spondyloarthritis international Society Health Index (ASAS HI). Societal health utility was assessed by the 5-level EuroQol-5 Dimension (EQ-5D-5L).

Results.

At Week 16, both doses of IXE in bDMARD-naïve and TNFi-experienced patients resulted in larger improvement in SF-36, ASAS HI, and EQ-5D-5L versus placebo. For SF-36, the largest improvements were seen for the domains of bodily pain, physical function, and role physical. A larger proportion of patients reaching improvement in ASAS HI ≥ 3 as well as an achievement of ASAS HI good health status was reported in patients treated with IXE. Improvements were maintained through Week 52.

Conclusion.

IXE significantly improved functioning and health as assessed by both generic and disease-specific measures, as well as societal health utility values in patients with r-axSpA, as measured by SF-36, ASAS HI, and EQ-5D-5L at Week 16, and improvements were sustained through 52 weeks.

Understanding differences between men and women with axial spondyloarthritis

Axial spondyloarthritis (axSpA) is a chronic inflammatory immune-mediated disease resulting in inflammatory low back pain and other inflammatory manifestations in peripheral joints and entheses. AxSpA encompasses both ankylosing spondylitis (AS), in which patients present with definitive sacroiliitis visible on radiographic imaging, as well as nonradiographic axSpA (nr-axSpA), in which such changes may not be discernable. Emerging evidence suggests that women and men experience axSpA differently. Although the prevalence of AS is approximately 2- to 3- fold higher in men than in women, nr-axSpA occurs with roughly equal frequency in women and men. The goal of this review is to increase awareness of sex differences in axSpA by exploring the distinct manifestations of disease and disease characteristics in women, the overall clinical burden, recommendations for diagnosis, and potential treatment options. We summarize and contextualize the results of recent studies that illuminate sex differences in nr-axSpA and AS, including differences in disease manifestation and progression. It is important that sex differences in axSpA are understood and considered when diagnosing and treating the spectrum of axSpA, including AS and nr-axSpA.

Update on Autoimmune Diseases Pathogenesis

BACKGROUND

Autoimmune diseases result from the interplay of cellular effectors like T and B cells, regulatory cells in addition to molecular factors like cytokines and regulatory molecules.

METHODS

Different electronic databases were searched in a non-systematic way to find out the literature of interest.

RESULTS

Pathogenesis of autoimmune diseases involves typical factors such as genetic background including HLA and non HLA system genes, environmental factors such as infectious agents and inflammatory cells mainly T and B lymphocytes abnormally activated leading to immune dysfunction. Other recently reported less typical factors such as micro-RNAs, circular RNAs, myeloperoxidase, vimentine and microbiome dysbiosis seem to be potential target therapies.

CONCLUSION

We aimed in this manuscript to review common factors in the pathogenesis of autoimmune diseases.

Clinical significance and prognostic value of tumor necrosis factor-α and dickkopf related protein-1 in ankylosing spondylitis

BACKGROUND

Ankylosing spondylitis (AS) frequently occurs in people aged 30-45 years, and its prevalence is generally believed to be between 0.1% and 1.4% globally. At present, the “gold standard” for diagnosis of AS requires the provision of pelvic X-rays, which makes it more difficult to perform in population-based epidemiological studies. Therefore, the identification of serological indicators related to the diagnosis, treatment, and prognosis of AS patients is of great significance.

AIM

To analyze the therapeutic, diagnostic significance and prognostic value of dickkopf-related protein-1 (DKK-1) and tumor necrosis factor-α (TNF-α) in AS.

METHODS

A total of 113 patients with active AS were selected as the research group, and 100 healthy subjects who underwent physical examination were selected as the control group. The levels of DKK-1 and TNF-α in peripheral blood in the two groups were compared. The diagnostic and predictive values of DKK-1 and TNF-α for AS were analyzed with ROC curves, and the factors influencing AS recurrence were analyzed with COX regression.

RESULTS

Before treatment, the research group showed lower DKK-1 levels but higher TNF-α levels than the control group (both ^aP < 0.05). In the research group, DKK-1 was up-regulated and TNF-α was down-regulated after 12 wk of treatment (^aP < 0.05). The area under the curve, sensitivity and specificity of DKK-1 combined with TNF-α for diagnosing AS were 0.934, 82.30% and 97.00%, respectively. Before treatment, the area under the curve, cutoff value, sensitivity and specificity of DKK-1 for predicting the curative effect were 0.825, 68.42 pg/mL, 73.68% and 80.00%, respectively, and those of TNF-α were 0.863, 32.79 ng/L, 92.11% and 77.33%, respectively. DKK-1 and TNF-α levels after treatment were closely related to the curative effect (^aP < 0.05). C-reactive protein, the Bath Ankylosing Spondylitis Disease Activity Index, DKK-1, and TNF-α were risk factors for AS recurrence (^aP < 0.05).

CONCLUSION

DKK-1 and TNF-α are effective in the diagnosis and treatment of AS and are risk factors for its recurrence. In addition, DKK-1 may be a potential target for the diagnosis of AS.

Discovery of Potential Serum Protein Biomarkers in Ankylosing Spondylitis Using Tandem Mass Tag-Based Quantitative Proteomics

Ankylosing spondylitis (AS) is a systemic, chronic, and inflammatory rheumatic disease that affects 0.2% of the population. Current diagnostic criteria for disease activity rely on subjective Bath Ankylosing Spondylitis Disease Activity Index scores. Here, we aimed to discover a panel of serum protein biomarkers. First, tandem mass tag (TMT)-based quantitative proteomics was applied to identify differential proteins between 15 pooled active AS and 60 pooled healthy subjects. Second, cohort 1 of 328 humans, including 138 active AS and 190 healthy subjects from two independent centers, was used for biomarker discovery and validation. Finally, biomarker panels were applied to differentiate among active AS, stable AS, and healthy subjects from cohort 2, which enrolled 28 patients with stable AS, 26 with active AS, and 28 healthy subjects. From the proteomics study, a total of 762 proteins were identified and 46 proteins were up-regulated and 59 proteins were down-regulated in active AS patients compared to those in healthy persons. Among them, C-reactive protein (CRP), complement factor H-related protein 3 (CFHR3), α-1-acid glycoprotein 2 (ORM2), serum amyloid A1 (SAA1), fibrinogen γ (FG-γ), and fibrinogen β (FG-β) were the most significantly up-regulated inflammation-related proteins and S100A8, fatty acid-binding protein 5 (FABP5), and thrombospondin 1 (THBS1) were the most significantly down-regulated inflammation-related proteins. From the cohort 1 study, the best panel for the diagnosis of active AS vs healthy subjects is the combination of CRP and SAA1. The area under the receiver operating characteristic (ROC) curve was nearly 0.900, the sensitivity was 0.970%, and the specificity was 0.805% at a 95% confidence interval from 0.811 to 0.977. Using 0.387 as the cutoff value, the predictive values reached 92.00% in the internal validation set (62 with active AS vs 114 healthy subjects) and 97.50% in the external validation phase (40 with active AS vs 40 healthy subjects). From the cohort 2 study, a panel of CRP and SAA1 can differentiate well among active AS, stable AS, and healthy subjects. For active AS vs stable AS, the area under the ROC curve was 0.951, the sensitivity was 96.43%, the specificity was 88.46% at a 95% confidence interval from 0.891 to 1, and the coincidence rate was 92.30%. For stable AS vs healthy humans, the area under the ROC curve was 0.908, the sensitivity was 89.29%, the specificity was 78.57% at a 95% confidence interval from 0.836 to 0.980, and the coincidence rate was 83.93%. For active AS vs healthy subjects, the predictive value was 94.44%. The results indicated that the CRP and SAA1 combination can potentially diagnose disease status, especially for active or stable AS, which will be conducive to treatment recommendation for patients with AS.

Allelic association with ankylosing spondylitis fails to correlate with human leukocyte antigen B27 homodimer formation

Expression of human leukocyte antigen (HLA)-B27 is strongly associated with predisposition toward ankylosing spondylitis (AS) and other spondyloarthropathies. However, the exact involvement of HLA-B27 in disease initiation and progression remains unclear. The homodimer theory, which proposes that HLA-B27 heavy chains aberrantly form homodimers, is a central hypothesis that attempts to explain the role of HLA-B27 in disease pathogenesis. Here, we examined the ability of the eight most prevalent HLA-B27 allotypes (HLA-B*27:02 to HLA-B*27:09) to form homodimers. We observed that HLA-B*27:03, a disease-associated HLA-B27 subtype, showed a significantly reduced ability to form homodimers compared with all other allotypes, including the non-disease-associated/protective allotypes HLA-B*27:06 and HLA-B*27:09. We used X-ray crystallography and site-directed mutagenesis to unravel the molecular and structural mechanisms in HLA-B*27:03 that are responsible for its compromised ability to form homodimers. We show that polymorphism at position 59, which differentiates HLA-B*27:03 from all other allotypes, is responsible for its compromised ability to form homodimers. Indeed, histidine 59 in HLA-B*27:03 leads to a series of local conformational changes that act in concert to reduce the accessibility of the nearby cysteine 67, an essential amino acid residue for the formation of HLA-B27 homodimers. Considered together, the ability of both protective and disease-associated HLA-B27 allotypes to form homodimers and the failure of HLA-B*27:03 to form homodimers challenge the role of HLA-B27 homodimers in AS pathoetiology. Rather, this work implicates other features, such as peptide binding and antigen presentation, as pivotal mechanisms for disease pathogenesis.

Trends in diagnostic prevalence and treatment patterns of male and female ankylosing spondylitis patients in the United States, 2006-2016

Background

There has been much variation between epidemiological studies that report the prevalence of ankylosing spondylitis (AS). This study aimed to analyze the diagnostic prevalence rates and treatment patterns of male and female AS patients in the United States adult insured population from 2006 to 2016.

Methods

Trends in AS prevalence were calculated for the 11-year period covering January 1, 2006 to December 31, 2016. Adult (18+ years old) AS patients were included in this retrospective analysis of medical and pharmacy claims data from the IBM Marketscan Commercial, Medicaid and Medicare-Supplemental Claims database. Prevalence was determined as having ≥1 AS diagnostic codes (ICD-9:720.0; ICD-10:M45.x). Trends in treatment patterns were also analyzed and stratified by gender.

Results

The AS prevalence increased from 0.04 to 0.09% from 2006 to 2016. The mean age between 2006 and 2016 ranged from 49.52–50.00 years. In 2006, approximately 40% of AS patients were female, while in 2016 over 47% of AS patients were female. Rates of use of TNF inhibitors and oral glucocorticoids increased, while NSAIDs and non-biologic DMARDs (sulfasalazine & methotrexate) rates decreased. Opioid use rates were stable. In 2016, males were more likely to be prescribed biologics, while females were more likely to be prescribed methotrexate, sulfasalazine, NSAIDs, muscle relaxants, anticonvulsants, opioids, and glucocorticoids.

Conclusions

The prevalence of AS diagnosis codes more than doubled between 2006 and 2016, but the very low prevalence suggests that AS continues to be underdiagnosed and under-addressed in routine clinical practice. Despite the increase in female AS patients, females were less likely to be prescribed biologics compared to male AS patients.

Translating Improvements with Ixekizumab in Clinical Trial Outcomes into Clinical Practice: ASAS40, Pain, Fatigue, and Sleep in Ankylosing Spondylitis

INTRODUCTION

Ixekizumab, a humanized interleukin-17A antibody, has shown efficacy in ankylosing spondylitis (AS), with a greater proportion of ixekizumab-treated patients achieving an ASAS40 (Assessment of Spondyloarthritis International Society 40) endpoint compared to placebo. An ASAS40 response is a high standard that is not routinely used in clinical practice. The goals of this study were (a) to measure improvement in ixekizumab-treated patients in the four ASAS treatment response domains and in other patient-reported outcomes, and (b) to determine how the ASAS response was associated with changes in spinal pain at night, fatigue, sleep, and the Short Form 36-Item Physical Component Summary (SF-36 PCS).

METHODS

The COAST-V and COAST-W trials were randomized, double-blind, controlled trials examining ixekizumab efficacy in patients with AS who were biologic disease-modifying antirheumatic drug (bDMARD)-naïve and tumor necrosis factor inhibitor (TNFi)-experienced, respectively. Data for the ASAS treatment response domains and other outcomes were collected through 16 weeks. Comparisons between treatment groups were made using a mixed-effects model for repeated measures. To determine how the ASAS response was associated with the changes in spinal pain at night, fatigue, sleep, and SF-36 PCS, comparisons were made between patient groups according to their level of treatment response (ASAS40 vs. ASAS20 vs. ASAS20 nonresponse) using analysis of covariance.

RESULTS

Compared with placebo, patients treated with ixekizumab reported significantly greater improvement in the four ASAS treatment response domains and other outcomes (p < 0.05). Results were consistent for bDMARD-naïve and TNFi-experienced patients. Compared to ASAS20 nonresponders, patients who achieved ASAS40 reported significantly greater mean changes in spinal pain at night (1.0 vs. 5.1 for bDMARD-naïve; 0.5 vs. 5.4 for TNFi-experienced), fatigue (0.6 vs. 3.8 for bDMARD-naïve; 0.2 vs. 3.9 for TNFi-experienced), sleep quality (1.1 vs. 4.0 for bDMARD-naïve; 0.8 vs. 4.9 for TNFi-experienced), and SF-36 PCS (2.6 vs. 11.6 for bDMARD-naïve; 1.2 vs. 12.6 for TNFi-experienced) (p < 0.0001).

CONCLUSION

Patients with AS who were treated with ixekizumab reported greater improvements in multiple patient-reported outcomes than patients who received placebo. Importantly, achieving ASAS40 was associated with a 2.6-fold to 5.3-fold greater improvement in pain, fatigue, sleep, and quality of life for bDMARD-naïve patients, and a 5.1-fold to 18.5-fold greater improvement for TNFi-experienced patients, compared to ASAS20 nonresponders.

TRIAL REGISTRATION

ClinicalTrials.gov identifiers: NCT02696785 and NCT02696798.

FUNDING

Eli Lilly and Company.

Efficacy of TNF inhibitors in advanced ankylosing spondylitis with total spinal fusion: case report and review of literature

Ankylosing spondylitis (AS) is a chronic and progressive inflammatory disorder that primarily affects the axial skeleton. Unfortunately, diagnosis of AS is often delayed compared to other rheumatologic conditions. It is not uncommon for patients to already have an advanced disease when the correct diagnosis is eventually made. TNF inhibitors are well-known and effective treatment options in patients with AS. However, many clinical trials have excluded patients with advanced AS. This paper reports a 45-year-old male with newly diagnosed AS with already fused sacroiliac joints, lumbar spine, and cervical spine. Due to persistent and severe pain despite having taken multiple NSAIDs, etanercept was prescribed. After 4 years of treatment, the patient continues to experience marked improvement of his AS symptoms without any significant adverse effects. This case illustrates etanercept can be an effective treatment in patients with advanced AS and is well tolerated. An extensive literature review is also carried out regarding this topic.

Improving Scoring Precision and Internal Construct Validity of the Bath Ankylosing Spondylitis Disease Activity Index Using Rasch Measurement Theory

OBJECTIVE

To test the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) according to Rasch Measurement Theory and investigate whether measurement precision can be improved.

METHODS

Secondary analysis of a BASDAI database. The data had been collected from individuals starting an Ankylosing Spondylitis Exercise Course at the Royal National Hospital for Rheumatic Diseases in Bath, UK.

RESULTS

Data were available for 250 participants (23.6% female) aged between 18 and 85 years (mean 52.8, SD 14.6). Initial fit of the data to the Rasch model appeared good and item thresholds were consistent, but local item dependence (LID) was identified. After addressing the LID, a unidimensional measure was achieved. The Person Separation Index (reliability) was 0.83 and the location of the items was well matched to that of the respondents. A transformation table was generated to convert total raw BASDAI scores into linearized Rasch transformed scores that form an interval scale. The Smallest Detectable Difference improved from 2 to 1.2. This finding suggests that a change score of > 1.2 points on the modified BASDAI is required to achieve meaningful change.

CONCLUSION

Applying the Rasch transformed scores simplifies completion and scoring of the measure and confirms internal construct validity. It also ensures linear measurement and justifies the use of parametric statistical analyses when analyzing datasets. The transformation table can be used with existing BASDAI datasets to allow direct comparisons of disease activity scores with those generated from future studies.

Use of machine learning techniques in the development and refinement of a predictive model for early diagnosis of ankylosing spondylitis

OBJECTIVE

To develop a predictive mathematical model for the early identification of ankylosing spondylitis (AS) based on the medical and pharmacy claims history of patients with and without AS.

METHODS

This retrospective study used claims data from Truven databases from January 2006 to September 2015 (Segment 1) and October 2015 to February 2018 (Segment 2). Machine learning identified features differentiating patients with AS from matched controls; selected features were used as inputs in developing Model A/B to identify patients likely to have AS. Model A/B was trained and developed in Segment 1, and patients predicted to have AS in Segment 1 were followed up in Segment 2 to evaluate the predictive capability of Model A/B.

RESULTS

Of 228,471 patients in Segment 1 without any history of AS, Model A/B predicted 1923 patients to have AS. Ultimately, 1242 patients received an AS diagnosis in Segment 2; 120 of these were correctly predicted by Model A/B, yielding a positive predictive value (PPV) of 6.24%. The diagnostic accuracy of Model A/B compared favorably with that of a clinical model (PPV, 1.29%) that predicted AS based on spondyloarthritis features described in the Assessment of SpondyloArthritis international Society classification criteria. A simplified linear regression model created to test the operability of Model A/B yielded a lower PPV (2.55%).

CONCLUSIONS

Model A/B performed better than a clinically based model in predicting a diagnosis of AS among patients in a large claims database; its use may contribute to early recognition of AS and a timely diagnosis.

Real-World Patient Experience on the Path to Diagnosis of Ankylosing Spondylitis

Introduction

We describe the journey to diagnosis of ankylosing spondylitis (AS) from the patient perspective and examine differences in this journey by sex.

Methods

US adults aged ≥ 18 years with a self-reported AS diagnosis were recruited online through CreakyJoints, a patient support community, and ArthritisPower, a patient research registry. Respondents completed a web-based survey on sociodemographics, disease burden, and diagnosis history. Results were stratified by sex and time to diagnosis using two-sample t tests and χ² tests, respectively, to observe differences across the groups; P < 0.05 was considered statistically significant.

Results

Among 235 respondents, 174 (74.0%) were female. Mean (SD) ages of female and male respondents were 48.6 (10.6) and 53.1 (10.3) years, respectively. From the time respondents began seeking medical attention, 87 were diagnosed within ≤ 1 year, 71 in 2–9 years, and 77 after ≥ 10 years. Symptoms that led respondents to seek treatment were back pain (73.2%) and joint pain (63.8%); fatigue and difficulty sleeping were more common among respondents with longer times to diagnosis. During the diagnosis process, men with AS tended to receive quicker AS diagnosis compared with women. Overall, commonly reported initial diagnoses among respondents with longer time to AS diagnosis included back problems and psychosomatic disorders. Significantly more women reported misdiagnoses of fibromyalgia (20.7 vs. 6.6%) and psychosomatic disorders (40.8 vs. 23.0%) compared with men.

Conclusions

Diagnosis delays and misdiagnoses were common among respondents with AS. Increasing awareness about AS among referring providers may minimize diagnosis delay.

Funding

Novartis Pharmaceuticals Corporation.

Plain Language Summary

Plain language summary available for this article.

Electronic Supplementary Material

The online version of this article (10.1007/s40744-019-0153-7) contains supplementary material, which is available to authorized users.

Characterization of Patients with Ankylosing Spondylitis Receiving Secukinumab and Reasons for Initiating Treatment: A US Physician Survey and Retrospective Medical Chart Review

Objectives

To characterize US patients with ankylosing spondylitis (AS) who were treated with secukinumab and to assess rheumatologist-reported reasons for prescribing treatment in clinical practice.

Methods

This descriptive analysis of data from a US retrospective medical chart review included patients aged ≥ 18 years diagnosed with AS who initiated secukinumab after 15 January 2016. Eligible rheumatologists used online forms to collect patient demographics, disease characteristics, co-morbidity profile, and treatment history prior to or on the index date, defined as the date of the first secukinumab prescription recorded in the medical chart. Information on physician-level characteristics and reasons for secukinumab prescription and dosing were also collected.

Results

Medical charts from 78 patients with AS who initiated secukinumab were reviewed by 25 rheumatologists between 7 July 2017 and 11 August 2017. Overall, 76.9% of patients were male, mean (SD) age was 39.8 (10.8) years, and 34.6% were biologic naïve. The most common reasons for secukinumab initiation among biologic-naïve and biologic-experienced patients, respectively, were efficacy/effectiveness (77.8%) and failure of other prior biologics (84.3%). Nearly all patients (94.9%) received a loading dose, including 150 mg every week (39.7%), 300 mg every week (53.8%), and other (1.3%). Overall, 73 patients (93.6%) received ≥ 1 maintenance secukinumab dose, of whom 56.2% and 43.8% received 150 mg and 300 mg, respectively, every 4 weeks.

Conclusions

In this US medical chart review of patients with AS who initiated secukinumab, approximately one-third were biologic naïve, and secukinumab efficacy/effectiveness and failure of other biologics were the most common reasons for initiating secukinumab.

Electronic supplementary material

The online version of this article (10.1007/s40801-018-0146-9) contains supplementary material, which is available to authorized users.

Tumor Necrosis Factor Inhibitor Discontinuation in Patients with Ankylosing Spondylitis: An Observational Study From the US-Based Corrona Registry

INTRODUCTION

Tumor necrosis factor inhibitors (TNFis) have shown efficacy for the treatment of ankylosing spondylitis (AS). However, many patients may discontinue or switch TNFis due to lack of effect or adverse events. As biologics with alternative mechanisms of action become available for the treatment of AS, it is important to better understand the characteristics of patients who discontinue or have an inadequate response to TNFis to help inform treatment choices regarding initiating or switching to a biologic therapy. This study compared demographic and clinical characteristics of patients with AS who discontinued vs. continued a TNFi by their second follow-up visit in the US-based Corrona Psoriatic Arthritis and Spondyloarthritis (PsA/SpA) Registry.

METHODS

All patients aged ≥ 18 years with AS enrolled in the Corrona PsA/SpA Registry between April 2013 and January 2015 who were receiving or had initiated a TNFi (index therapy) at the time of registry enrollment (baseline) and had ≥ 2 follow-up visits were included. Patient demographics, clinical characteristics, and patient-reported outcome scores at baseline were compared between cohorts of patients who discontinued or continued their TNFi by the second follow-up visit.

RESULTS

Of the 155 included patients, 37 (23.9%) discontinued their index TNFi therapy by the second follow-up visit (mean follow-up, 17.8 months). Patients who discontinued their TNFi were older (mean age, 52.1 vs. 46.6 years; P = 0.04), were more likely to be obese (59.5% vs. 34.2%; P < 0.01), and had worse mean Bath Ankylosing Spondylitis Disease Activity Index and Bath Ankylosing Spondylitis Functional Index scores (4.8 vs. 3.5 and 4.2 vs. 2.8, respectively; P = 0.01 for both) at baseline than those who continued their TNFi.

CONCLUSIONS

The results of this real-world study provide insight into the demographic and clinical characteristics of patients with AS who discontinue vs. continue TNFi therapy in US clinical practice.

FUNDING

Corrona, LLC. Plain language summary available for this article.

Characterization of Patients With Ankylosing Spondylitis and Nonradiographic Axial Spondyloarthritis in the US-Based Corrona Registry

Objective

To describe the characteristics of patients with ankylosing spondylitis (AS) and patients with nonradiographic axial spondyloarthritis (SpA) in the US.

Methods

Demographics, clinical characteristics, patient‐reported outcomes, and treatment characteristics of patients with AS and those with nonradiographic axial SpA were assessed at the time of enrollment in the Corrona Psoriatic Arthritis/Spondyloarthritis Registry. Patients with AS were defined as those who fulfilled the 1984 modified New York criteria for AS; patients with nonradiographic axial SpA were defined as all other patients with axial SpA who did not fulfill the radiology criterion.

Results

Of the 407 patients with a diagnosis of axial SpA who were included in this study, 310 had AS, and 97 had nonradiographic axial SpA. Although patients with nonradiographic axial SpA were younger and showed a trend toward a shorter symptom duration, the nonradiographic axial SpA and AS groups shared a similar disease burden, as reflected by comparisons of disease activity and function, quality of life, pain, fatigue, job absenteeism, and loss of work productivity (all P > 0.05). The proportions of patients with nonradiographic axial SpA and patients with AS who received prior biologic disease‐modifying drugs (DMARDs) (74.2% and 64.8%, respectively) or were currently receiving biologic DMARDs (63.9% and 61.3%, respectively) were also similar (P > 0.05).

Conclusion

This was the first nationwide study to characterize patients with AS and nonradiographic axial SpA in the US. Consistent with studies published outside of the US, this study showed that patients with nonradiographic axial SpA and patients with AS shared a comparable degree of disease burden and had similar treatment patterns in clinical practice.