An epidemiological survey of low back pain and axial spondyloarthritis in a Chinese Han population

Design of the COMEBACK and BACKHOME Studies, Longitudinal Cohorts for Comprehensive Deep Phenotyping of Adults with Chronic Low-Back Pain (cLBP): a part of the BACPAC Research Program

Objective

The University of California, San Francisco (UCSF) Core Center for Patient-centric, Mechanistic Phenotyping in Chronic Low Back Pain (REACH) is one of the three NIH Back Pain Consortium (BACPAC) Research Programs Mechanistic Research Centers (MRCs). The goal of UCSF REACH is to define cLBP phenotypes and pain mechanisms that can lead to effective, personalized treatments for patients across the population. The primary objective of this research project is to address the critical need for new diagnostic and prognostic markers, and associated patient classification protocols for chronic low back pain (cLBP) treatment.

Design

To meet this objective, REACH is conducting two large investigator-initiated translational research cohort studies called: The Longitudinal Clinical Cohort for Comprehensive Deep Phenotyping of Chronic Low-Back Pain (cLBP) Adults Study (comeBACK) and the Chronic Low-Back Pain (cLBP) in Adults Study (BACKHOME).

Setting

comeBACK is a longitudinal multicenter in-person observational study of 450 adults with chronic low back pain designed to perform comprehensive deep phenotyping. While, the BACKHOME study is a site-less longitudinal observational e-cohort of approximately 3000 U.S. adults with cLBP. To our knowledge, BACKHOME is the largest prospective remote registry of nationwide adults with cLBP.

Methods

Both the comeBACK and BACKHOME studies are collecting a robust and comprehensive set of risk factors, outcomes, and covariates in order to perform deep phenotyping of cLBP patients based on combined biopsychosocial variables to: define cLBP subtypes, establish phenotyping tools for routine clinical evaluation, and lead to improved cLBP outcomes in the future. The data from both studies will be used to establish techniques to develop a patient-centric definition of treatment success and to analyze cLBP patient traits to define clinically useful cLBP phenotypes, using a combination of traditional data analyses and deep learning methods.

Conclusions

These 2 pivotal studies, in conjunction with the ancillary studies being performed in both comeBACK and BACKHOME, and the other BACPAC-consortium research projects, we will be able to address a number of diagnostic and therapeutic issues in this complex and diverse patient population with cLBP. These studies will help clarify biopsychosocial mechanisms of cLBP with the aim to provide a foundation to improve the evaluation of treatment effectiveness and to spur new avenues of therapeutic research, including personalized outcome measures that constitute a clinically meaningful treatment effect for individual cLBP patients.

Diagnostic delay and its associated factors in Chinese axial spondyloarthritis: A single-center study of 1295 patients

AIM

To delineate the landscape of diagnostic delay in Chinese axial spondyloarthritis (axSpA), investigate its associated factors, and explore its potential impact on medication modalities.

METHODS

A total of 1295 patients fulfilling the ASAS classification criteria were obtained. Demographic and clinical data were collected through face-to-face interviews, based on predesigned questionnaires and available medical records. Logistic regression analyses under univariate and multivariable model were performed, using the median of diagnostic delay as the cut-off point for group classification. Differences between early- and late-diagnosed groups were subsequently compared by the Pearson chi-square test or Mann-Whitney U test.

RESULTS

Of 1295 axSpA patients, 80.3% were male and the median of disease duration was 8.0 years. The median (IQR) diagnostic delay in Chinese axSpA was 3.0 (1.0 ~ 7.0) years and 24.8% of them reported a history of misdiagnosis. Older age at onset (OR = 0.97, p < .001) and higher education attainment (p = .001) were correlated with early diagnosis of axSpA, whereas coming from less developed areas (p = .002), a history of peripheral arthritis at the time of diagnosis (OR = 1.58, p = .002) and history of misdiagnosis (OR = 1.98, p < .001) increased the risk of diagnostic delay. Oral medication modalities were similar between two groups, but the proportion with no medication ever was higher in the late-diagnosed group (26.5% vs. 20.7%, p = .02).

CONCLUSION

Our findings depicted a detailed spectrum of diagnostic delay in Chinese axSpA, verified five associated factors that may help facilitate timely diagnosis of axSpA, and pinpointed that timely medication was unsatisfying, especially in the late diagnosis group.

Disease control in patients with ankylosing spondylitis in real clinical practice in Spain: Results of the MIDAS study

INTRODUCTION AND OBJECTIVES

Understanding the disease activity is fundamental to improve patient prognosis and patients' quality of life. MiDAS study described disease activity in ankylosing spondylitis (AS) Spanish patients and the proportion of them with controlled disease.

METHODS

Observational, cross-sectional, multicenter study carried out under conditions of routine clinical practice. Adult (≥18 years) patients with ≥6 months since AS diagnosis treated ≥3 months prior to inclusion. The primary endpoint was the percentage of patients with low disease activity assessed through BASDAI (primary endpoint) and ASDAS-CRP (secondary endpoint).

RESULTS

313 AS patients included: 75.7% male; 78.5% HLA-B*27 positive; mean (SD) baseline age of 50.4 (12.0) years; mean (SD) disease duration of 15.5 (11.6) years; 73.5% were treated with biological disease-modifying antirheumatic drugs (DMARDs), 22.4% with non-biological DMARDs and 53.7% with non-steroidal anti-inflammatory drugs, alone or in combination. Monotherapy with biologics and non-biologics was used by 29.7% and 26.8% of patients, respectively. According to BASDAI, 38.0% were in remission (BASDAI≤2) and 64.5% showed adequate disease control (BASDAI<4). According to ASDAS-CRP, 29.4% achieved remission (ASDAS-CRP<1.3) and 28.1% low disease activity (1.3≤ASDAS-CRP<2.1).

CONCLUSIONS

Almost two thirds of the AS patients recruited had low disease activity, with about one third of them being in remission (BASDAI≤2, ASDAS-CRP<1.3). These results highlight the existing room for improvement in treating AS patients in clinical practice.

Spectrum of Spondyloarthritis Among Chinese Populations

PURPOSE OF REVIEW

This review aims to emphasize interesting and important new findings with a focus on the spectrum of spondyloarthritis (SpA) in China.

RECENT FINDINGS

Over the past decade, significant advances have been made in the investigation of SpA epidemiology, the exploration of genetic and environmental risk factors, the identification of clinical features, and the updating of treatment protocols in the Chinese population. The prevalence of ankylosing spondylitis (AS) in China is 0.20-0.42%, and the prevalence of HLA-B27 in AS patients is 88.8-89.4%. HLA-B*2704 is the most common subtype in Chinese AS patients, followed by HLA-B*2705. HLA-A*01, more precisely HLA-A*01:01, may be associated with psoriatic arthritis (PsA). Tumor necrosis factor inhibitors and IL-17A inhibitors have been shown to be effective and safe for AS patients in China. Juvenile-onset AS is relatively rare, accounting for only 9.1% of the AS population. The prevalence of arthritis related to inflammatory bowel disease is 6.9 to 7.2%. A Chinese study showed that the most frequently prescribed medication was methotrexate (66.4%). Biological agents were prescribed in only16.4% of patients with PsA. This review summarizes the latest research in the epidemiology, pathogenesis, clinical manifestations, and management of SpA among Chinese populations. Multiple HLA associations with SpA have also been described, and it is hoped that discoveries of such ethnic-specific risk factor(s) and understanding of their pathological mechanisms may potentially lead to newer targeted therapies for the Chinese populations worldwide.

Association analysis of B7-H3 and B7-H4 gene single nucleotide polymorphisms in susceptibility to ankylosing spondylitis in eastern Chinese Han population

This study was conducted to describe the association between the genetic variation of the recently identified immune checkpoint molecules B7-H3 and B7-H4, and the susceptibility to ankylosing spondylitis (AS). Two single nucleotide polymorphisms (SNPs) of B7-H3 gene and three SNPs of B7-H4 gene were genotyped in 649 AS patients and 646 age- and sex-matched healthy controls. Allele, genotype frequencies and different inheritance models were performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs), and the demographic and clinical parameters of patients were recorded. Our data indicated that B7-H4 rs10801935 and rs3738414 polymorphisms were correlated with AS susceptibility. In the stratification analyses, the minor A allele and GA genotype of B7-H4 rs3738414 increased the risk of AS in male patients (OR = 1.244, 95%CI = 1.026-1.508; OR = 1.453, 95%CI = 1.120-1.886, respectively). However, the association did not reach statistical significance after Bonferroni correction. Furthermore, haplotype analysis revealed that B7-H4 haplotype block TAG was a risk factor for the onset of AS (OR = 1.190, 95%CI = 1.020-1.389). These findings suggested that B7-H4 gene polymorphism may contribute to AS susceptibility in eastern Chinese Han population.

Metabolomic analysis of biochemical changes in the tissue and urine of proteoglycan-induced spondylitis in mice after treatment with moxibustion

BACKGROUND

Moxibustion is widely used in East Asian countries to manage the symptom of rheumatic diseases. The aim of this study was to identify potential metabolic profiles of moxibustion on relieving ankylosing spondylitis (AS) mice through UHPLC-Q-TOF/MS metabolomic study.

METHODS

Thirty-two female Balb/c mice were randomized into healthy control (HC), AS model, moxibustion at acupuncture points (MA) in AS model, and moxibustion at non-acupuncture points (MNA) AS model groups. Moxibustion was administered daily at GV4, bilateral BL23 and bilateral ST36 acupuncture points for four weeks in the MA group. The overall health status, the thickness of hind paws and the tissue concentrations of IL-1β, PGE2, IL-6 and TNF-α were assessed. The UHPLC-Q-TOF/MS was used to explore the perturbations of endogenous metabolites in tissue and urine of AS model mice intervened by moxibustion.

RESULTS

Compared with the AS group, the overall health status was significantly improved after 4-week moxibustion intervention (p < 0.05). The results also showed that MA significantly reduced the levels of paw thickness and decreased the levels of four cytokines in the tissue (p < 0.01). Thirty-seven endogenous metabolites identified by the OPLS-DA were considered to be contributing to therapeutic effects of moxibustion. Moreover, metabolic pathway analysis further revealed that the identified metabolites were mainly involved in TCA cycle, Lipid metabolism, Amino Acid metabolism, Intestinal flora metabolism and Purine metabolism.

CONCLUSIONS

UHPLC-Q-TOF/MS based metabolomics approach, as a novel and powerful tool, can help us to gain the insights into potential mechanisms of action of moxibustion for AS.

Diagnostic value of anti-CD74 antibodies in early and late axial spondyloarthritis and its relationship to disease activity

OBJECTIVES

This study was designed to evaluate the role of anti-CD74 antibodies in diagnosis of axial spondyloarthritis (axSpA) and their relationship to disease duration and disease activity.

METHODS

Fifty patients with axSpA, 15 patients with RA and 15 healthy subjects were included in the study. Clinical examination and laboratory tests were done. The ESR, CRP level and ASDAS were measured as markers of the disease activity. Quantitative determination of human CD74 IgG antibodies was done.

RESULTS

The mean age of the patients was 38.22 (S.D.12.20) years. The level of CD74 autoantibodies was significantly higher in axSpA in comparison to control groups. Most patients with positive articular and extra-articular manifestations were positive for CD74 autoantibodies. In patients with inactive disease, 33.3% were positive for CD74 autoantibodies, as were 83% with active disease. High percentages of patients with early and late axSPA were CD74 autoantibody positive. The majority of patients with positive disease activity in early and late axSpA were CD74 autoantibody positive. CD74 autoantibodies had 80% sensitivity vs both control groups with 87% specificity vs the healthy control group and 80% vs the RA control group in the diagnosis of axSpA.

CONCLUSIONS

The frequency of positive anti-CD74 IgG antibodies was as high in patients with early axSpA as in those with late axSpA, with no significant differences. There was a significant difference in the frequency of positive anti-CD74 IgG antibodies between patients with positive and negative disease activity. Based on the sensitivity and specificity of anti-CD74 IgG, this is a promising diagnostic tool to support the clinical diagnosis of axSpA.

Medical ozone therapy in facet joint syndrome: an overview of sonoanatomy, ultrasound-guided injection techniques and potential mechanism of action

Facet joint osteoarthritis is the most prevalent source of facet joint pain and represents a significant cause of low back pain. Oxygen-ozone therapy has been shown to have positive results in acute and chronic spinal degeneration diseases and it could be a safe and efficacious alternative to traditional facet joint conservative treatments. This review article explains the interventional facet joint management with ultrasound-guided oxygen-ozone therapy, providing an anatomy/sonoanatomy overview of lumbar facet joints and summarizing the potential mechanism of action of oxygen-ozone in the treatment of facet joint osteoarthritis, not yet fully understood.

Recognizing Axial Spondyloarthritis: A Guide for Primary Care

Axial spondyloarthritis (axSpA) is an important cause of chronic low back pain and affects approximately 1% of the US population. The back pain associated with axSpA has a characteristic pattern referred to as inflammatory back pain (IBP). Features of IBP include insidious onset before age 45 years, association with morning stiffness, improvement with exercise but not rest, alternating buttock pain, and good response to treatment with nonsteroidal anti-inflammatory drugs. In patients with IBP, it is essential to look for other features associated with spondyloarthritis (SpA), such as enthesitis, dactylitis, peripheral arthritis, extra-articular manifestations (eg, psoriasis, uveitis, or inflammatory bowel disease), human leukocyte antigen B27 positivity, and a family history of SpA. Axial SpA is underrecognized, and a delay of several years between symptom onset and diagnosis is common. However, with new and effective therapies available for the treatment of active axSpA, early recognition and diagnosis are of critical importance. For this narrative review, we conducted a literature search of English-language articles using PubMed. Individual searches were performed to identify potential articles of interest related to axSpA (search terms: ["axSpA" OR "axial SpA" OR "axial spondyloarthritis" OR "ankylosing spondylitis"]) in combination with terms related to IBP ("inflammatory back pain" OR "IBP" OR "chronic back pain" OR "CBP" OR "lower back pain" OR "LBP"), diagnosis (["diagn∗" OR "classification"] AND ["criteria" OR "recommend∗" OR "guidelines"]), and referral ("refer∗"). No date range was formally selected, as we were interested in providing an overview of the evolution of these concepts in clinical practice. We supplemented the review with insights based on our clinical expertise. Patients with chronic back pain should be screened for IBP and other SpA features; suspicion for axSpA should trigger referral to a rheumatologist for further evaluation.

The effectiveness of Du moxibustion for ankylosing spondylitis: A protocol for systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Ankylosing spondylitis (AS) is a common progressive autoimmune inflammatory disease. Du moxibustion can effectively treat AS with few adverse reactions. The aim of this protocol is to systematically investigate the effectiveness and safety for management of AS with Du moxibustion.

METHODS

Seven relevant databases, namely, PubMed, Cochrane Library, Embase, Chinese Biomedical Literatures Database (CBM), China National Knowledge Infrastructure (CNKI), WangFang Database (WF), Chinese Scientific Journal Database (VIP) will be searched from their inception until May 1st, 2020. All clinical randomized controlled trials containing eligible interventions(s) and outcome(s) will be included, regardless of blinding or publication types. Two reviewers will independently retrieval databases, extract data, and then assess the quality of studies. Data synthesis will be conducted by RevMan 5.3 software. We regard the effective rate, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Visual Analogue Scale (VAS) as the primary outcomes, and the secondary outcomes contain C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), finger-to-floor distance (FFD), occiput to wall distance (OWD), and side effects. The result about the curative effect and safety of Du moxibustion for AS will be presented as risk ratio for dichotomous data and mean differences with a 95% confidence interval for continuous data.

RESULTS

The finding will be presented in a journal or related conferences.

CONCLUSIONS

This study expects to provide high-quality, evidence-based recommendations on further treatment for clinical guidance.

PROSPERO REGISTRATION NUMBER

CRD42020158727.

Prevalence of ankylosing spondylitis in a Chinese population: a systematic review and meta-analysis

Ankylosing spondylitis (AS) is a common inflammatory rheumatic disease that affects the axial skeleton. In this study, we systematically reviewed Chinese AS epidemiological studies from the past 15 years to elucidate its prevalence and provide scientific data for China's health care system. AS epidemiological research in China was summarized by conducting a literature review. A review and statistical analysis of the literature on the epidemiology of AS in mainland China published from May 2005 to May 2019 were performed via a meta-analysis. We calculated the prevalence of AS and analysed differences by sex, region, and population source using STATA12.0 software. Eleven papers including 122,558 subjects from mainland China were included. Over the past 15 years, the total prevalence of AS in mainland China was 0.29% (95% CI 0.22-0.35%), ranging from 0.42% (95% CI 0.31-0.52%) in males to 0.15% (95% CI 0.13-0.18%) in females; the difference in the prevalence of AS by sex was statistically significant (P < 0.001). The prevalence of AS in both southern and northern China was 0.31% (95% CI 0.21-0.42% and 0.21-0.40%, respectively), with no significant difference noted (P = 0.816 > 0.005). The prevalence of AS in Chinese military populations was 0.27% (95% CI 0.09-0.45%), and in community populations, it was 0.29% (95% CI 0.23-0.35%). There was no statistically significant difference in the prevalence of AS by sampling resource (P = 0.115 > 0.005). The prevalence of AS in China was 0.29% and continues to increase. Sex differences in its prevalence were identified; the prevalence rate was 2.8 times higher in males than in females. Epidemiologists in China should formulate precise scientific investigations to provide additional authoritative epidemiological data for the prevention and treatment of AS.

Early recognition of patients with axial spondyloarthritis—evaluation of referral strategies in primary care

Objective

Chronic inflammatory back pain (IBP) is frequently reported in axial SpA (axSpA) but also in the general population. We evaluated a recently proposed two-step referral system for early recognition of axSpA in primary care and compare it with other combinations of symptoms and SpA-related items.

Methods

Consecutive chronic back pain patients ≤45 years of age answered a questionnaire and were seen by a primary care physician who decided whether HLA-B27 needed to be determined. They were then referred to a rheumatologist who made the diagnosis. Generally sticking to the two-step system with HLA-B27 as an additional option, combinations with a sensitivity ≥90% and a likelihood ratio &gt;4 were compared.

Results

A total of 326 patients were included, 46 of whom were diagnosed with axSpA (14.1%). The sensitivity of the strategy was 87%, the specificity was 56.8% and the positive and negative predictive values were 24.8% and 96.4%, respectively. A ‘good response to NSAIDs’, ‘morning stiffness &gt;30 min’ and ‘elevated C-reactive protein’ performed best, with a sensitivity of 91%, specificity of 67%, positive predictive value of 31% and negative predictive value of 98%. On that basis, only three patients had to be seen by a rheumatologist to diagnose one.

Conclusion

The earlier proposed referral system worked well but was outperformed by other combinations with high sensitivity and better specificity, which deserve to be prospectively studied.

Analysis of 47 Non-MHC Ankylosing Spondylitis Susceptibility Loci Regarding Associated Variants across Whites and Han Chinese

OBJECTIVE

To present a systematic evaluation of 47 non-MHC ankylosing spondylitis (AS) susceptibility loci that have been initially discovered through white genome-wide association studies in Han Chinese.

METHODS

Originally, 10,743 samples representing north and south Chinese in 4 datasets were obtained. After data quality control and imputation, metaanalysis results of 94,621 variants within 47 loci were extracted. Four ERAP1 single-nucleotide polymorphisms (SNP) and HLA-B27 tag SNP rs13202464 were used for interaction analysis. Population-attributable risk percentages of AS-associated variants were compared. Functional annotations of AS-associated variants were conducted using HaploReg, RegulomeDB, and rVarBase databases.

RESULTS

We revealed 16 AS-associated variants with nominal evidence in Han Chinese, including rs10865331 (p = 6.30 × 10^-10), rs10050860 (p = 4.09 × 10^-5) and rs8070463 (p = 1.03 × 10^-4). Potential susceptible SNP within these 47 loci were also identified, such as rs13024541 (2p15), rs17401719 (5q15), and rs62074054 (17q21). Epistatic interactions between 3 ERAP1 SNP (rs17401719, rs30187, and rs10050860) and HLA-B27 were confirmed. Among the 16 AS-associated variants, rs30187 showed weaker risk effect, while rs10050860 and rs12504282 seemed to attribute more risk in Han Chinese than in whites. Further genomic annotation pinpointed 35 candidate functional SNP, especially in the 2p15, ERAP1, and NPEPPS-TBKBP1 regions.

CONCLUSION

Our results provided a detailed spectrum of all the reported non-MHC AS susceptibility loci in Han Chinese, which comprehensively exhibited the ethnic heterogeneity of AS susceptibility and highlighted that 2p15, ERAP1, and NPEPPS-TBKBP1 regions may play a critical role in AS pathogenesis across diverse populations.

Relationship between Vitamin D levels and pain and disease activity in patients with newly diagnosed axial spondyloarthritis

OBJECTIVES

To explore the relationship between Vitamin D levels and pain and disease activity in patients with newly diagnosed axial spondyloarthritis (axSpA).

METHODS

A convenience sample of 131 newly diagnosed axSpA patients and 60 healthy controls was recruited from July 2016 to December 2018. Serum 25-hydroxyvitamin D [25(OH)D] was measured to assess vitamin D levels. Disease activity was assessed by objective indicators [Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), the Bath Ankylosing Spondylitis Metrology Index (BASMI)], patient-reported questionnaires [the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), and the Bath Ankylosing Spondylitis Functional Index (BASFI)]. Pain intensity and interference were also assessed.

RESULTS

Vitamin D insufficiency [serum 25(OH) D levels<50 nmol/L]was found in 46 (35.1%) and 25 (43.3%) of the axSpA patients and the healthy controls, respectively. Female patients had higher risk (OR:4.928; 95% CI: 1.921-12.642) for vitamin D insufficiency than male patients. Vitamin D was positively correlated with CRP, ESR level, the BASFI, and the BASMI. Logistic regression showed that vitamin D levels were not associated with pain, or disease activity in the newly diagnosed axSpA patients. Gender was the only predictive variable for vitamin D levels.

CONCLUSIONS

Vitamin D insufficiency was prevalent in both newly diagnosed axSpA patients and healthy controls. There was no association between vitamin D and pain and disease activity in the newly diagnosed axSpA patients. Monitoring vitamin D levels is important and early intervention for vitamin D insufficiency is needed, especially in female patients.

Prevalence of ankylosing spondylitis in Spain: EPISER2016 Study

Objective: The aim of this study was to estimate the prevalence of ankylosing spondylitis (AS) in Spain.Method: This is a cross-sectional, population-based study of people aged 20 years or older in Spain. Randomly selected individuals were contacted by telephone and rheumatic disease screening was performed. If the first screening was positive, medical records were then reviewed and/or a telephone questionnaire was conducted by a rheumatologist, followed by an appointment if necessary. Cases had to fulfil the modified New York (mNY) criteria.Results: In total, 4916 individuals were included, of whom 355 had a positive screening result for AS. Of these, 11 were classified as AS. An additional individual who reported a prior diagnosis of rheumatoid arthritis had a diagnosis of AS confirmed on review of the medical records. Estimated prevalence was 0.26% (95% CI 0.14-0.49).Conclusion: EPISER2016 is the first population-based study to estimate the prevalence of AS in Spain, which has been estimated as being similar to that in other European countries.

Clinical Characteristics of Patients with Spondyloarthritis in Japan in Comparison with Other Regions of the World

Objective.

To delineate clinical characteristics of patients with spondyloarthritis (SpA) in Japan in comparison to other areas of the world.

Methods.

Using the ASAS-COMOSPA (Assessment of Spondyloarthritis international Society–COMOrbidities in SPondyloArthritis) data, an international cross-sectional observational study of patients with SpA, we analyzed information on demographics, disease characteristics, comorbidities, and risk factors. Patients were classified by region: Japan, other Asian countries (China, Singapore, South Korea, Taiwan), and non-Asian countries (Europe, the Americas, Africa). Patient characteristics, including diagnosis and treatment, were compared.

Results.

Among 3984 patients included in the study, 161 were from centers in Japan, 933 from other Asian countries, and 2890 from other regions. Of patients with SpA in Japan, 42 (26.1%) had peripheral SpA, substantially more than in other countries. This trend was explained by the predominance of psoriatic arthritis (PsA) among Japanese patients with SpA. In contrast to the relatively low number in Japan, 54% of patients from other Asian countries had pure axial SpA (axSpA) without peripheral features. HLA-B27 testing, considered an integral part of the classification of axSpA, was performed in only 63.6% of Japanese patients with axSpA. More than half of Japanese patients with axSpA were classified using imaging criteria.

Conclusion.

In our study, there was a more substantial number of peripheral SpA cases observed in Japan compared to other parts of Asia and other regions of the world. Aside from ethnic differences, increasing recognition of PsA in Japan, as well as a potential underdiagnosis of axSpA due to the insufficient use of HLA-B27 testing, may partly explain regional discrepancies.

Diagnostic accuracy of inflammatory back pain for axial spondyloarthritis in rheumatological care

Objective

Inflammatory back pain (IBP), the key symptom of axial spondyloarthritis (axSpA), including ankylosing spondylitis, has been proposed as a screening test for patients presenting with chronic back pain in primary care. The diagnostic accuracy of IBP in the rheumatology setting is unknown.

Methods

Six rheumatology centres, representing secondary and tertiary rheumatology care, included routinely referred patients with consecutive chronic back pain with suspicion of axSpA. IBP (diagnostic test) was assessed in each centre by an independent (blinded) rheumatologist; a second (unblinded) rheumatologist made the diagnosis (axSpA or no-axSpA), which served as reference standard.

Results

Of 461 routinely referred patients, 403 received a final diagnosis. IBP was present in 67.3%, and 44.6% (180/403) were diagnosed as axSpA. The sensitivity of IBP according to various definitions (global judgement, Calin, Berlin, Assessment of SpondyloArthritis international Society criteria for IBP) was 74.4%–81.1 % and comparable to published figures, whereas the specificity was unexpectedly low (25.1%–43.9%). The resulting positive likelihood ratios (LR+) were 1.1–1.4 and without major differences between sets of IBP criteria. The presence of IBP according to various definitions increased the probability of axSpA by 2.5%–8.4% only (from 44.6% to 47.1%–53.0%).

Conclusions

The diagnostic utility of IBP in the rheumatology setting was smaller than expected. However, this was counterbalanced by a high prevalence of IBP among referred patients, demonstrating the effective usage of IBP in primary care as selection parameter for referral to rheumatology. Notably, this study illustrates potential shifts in specificity and LR+ of diagnostic tests if these tests are used to select patients for referral.

Psychological Treatment Strategy for Chronic Low Back Pain

Studies have indicated that chronic low back pain (LBP) should be approached according to its morphological basis and in consideration of biopsychosocial interventions. This study presents an updated review on available psychological assessments and interventions for patients with chronic LBP. Psychosocial factors, including fear-avoidance behavior, low mood/withdrawal, expectation of passive treatment, and negative pain beliefs, are known as risk factors for the development of chronic LBP. The Örebro Musculoskeletal Pain Questionnaire, STarT Back Screening Tool, and Brief Scale for Psychiatric Problems in Orthopaedic Patients have been used as screening tools to assess the development of chronicity or identify possible psychiatric problems. The Pain Catastrophizing Scale, Pain Self-Efficacy Questionnaire, and Injustice Experience Questionnaire are also widely used to assess psychosocial factors in patients with chronic pain. With regard to interventions, the placebo effect can be enhanced by preferable patient-clinician relationship. Reassurance to patients with non-specific pain is advised by many guidelines. Cognitive behavioral therapy focuses on restructuring the negative cognition of the patient into realistic appraisal. Mindfulness may help improve pain acceptance. Self-management strategies with appropriate goal setting and pacing theory have proved to improve long-term pain-related outcomes in patients with chronic pain.

[Functional outcomes of patients receiving total hip arthroplasty for ankylosing spondylitis]

OBJECTIVE

To assess the functional outcomes of patients undergoing total hip arthroplasty for ankylosing spondylitis (AS).

METHODS

Between March, 2013 and May, 2016, 75 AS patients with ankylosed hip (involving 92 hips) underwent unilateral biological artificial total hip arthroplasty. The patients were followed up for 12-24 months and the changes in VAS score of the affected hip were evaluated. The changes in the range of motion (ROM) of hip, employment, BASFI and BASDAI score, and Harris score were analyzed after the operations.

RESULTS

Significant improvements in general joint mobility, clinical symptoms and hip joint functions were achieved in all the patients. The average VAS score was significant reduced from 6.51± 1.32 preoperatively to 2.47±0.38 after the operation. Significant improvements were also achieved after the operation in the average Harris hip score (from 22.51±3.32 to 89.17±2.52), the total ROM (from 0 to 171.50±30.30), and mean BASFI score (from 6.2±2.6 to 2.3±1.2; all P < 0.05). At the final follow up, 42 hips showed excellent outcomes, 38 hips had good outcomes, and 12 hips had acceptable outcomes, with a good outcome rate of 87%. By 6 and 12 months after the operation, 6 and 32 of the 75 patients returned to work. No neurovascular injuries, infections or dislocations was found in the patients during the follow-up; 1 patient had prosthesis loosening found by X-ray ordered for complaint of pain in the affected hip 4 months postoperatively. Five patients had heterotopic ossifications, including 3 grade Ⅰ hips and 2 grade Ⅱ hips according to the Brooker grading system.

CONCLUSIONS

Biological artificial total hip arthroplasty is effective for treatment of ankylosing spondylitis with hip stiffness with good functional outcomes of the hip joint.

An epidemiological study of the prevalence rate of inflammatory back pain and axial spondyloarthritis in a university in the south of China

Inflammatory back pain (IBP) is an important clinical feature for axial spondyloarthritis (SpA). Yet, little is known about their prevalences in China. We conducted an epidemiological study in a university to detect the prevalences of IBP and axial SpA according to the Assessment of SpondyloArthritis International Society (ASAS) criteria. We investigated 3770 participants from South China Agricultural University by face-to-face questionnaires and evaluated the prevalences of chronic low back pain (CLBP) and IBP. In addition, 333 students including all IBP patients volunteered to do HLA-B27 test, and we performed X-ray examination on students with suspect axial SpA. Axial SpA was confirmed by rheumatologists according to ASAS criteria. The mean (± SD) age of screened population was 19.48 (± 2.80) years, while female to male ratio was 1.45:1 (2229/1541). Seven hundred thirty-one (19.39%) of all participants had CLBP and 111 (2.94%) had IBP. Among the 333 students receiving HLA-B27 test, 13 (0.34%, 13/3770) fulfilled ASAS criteria for axial SpA. Nine students had sacroiliitis on imaging plus at least one SpA feature (IBP and positive HLA-B27 results). Four students had positive HLA-B27 plus at least two other SpA features (arthritis/enthesitis and good response to NSAIDs). For CLBP, female/male was 485/246. For axial SpA, female/male was 4/9(P = 0.014). In southern China, the prevalences of CLBP and IBP were respectively 19.39 and 2.94% in university, and the prevalence of axial SpA was 0.34%. Although more female students had CLBP, males were more likely to suffer from axial SpA.

Smoking quantity determines disease activity and function in Chinese patients with ankylosing spondylitis

The objective of this study was to systemically and comprehensively evaluate the associations between smoking and disease outcomes in patients with ankylosing spondylitis (AS). Information on smoking, clinical features, and sociodemographic characteristics was collected by a questionnaire administered directly to the patient. Group differences were analyzed by t test or chi-square test. Logistic regression analysis was conducted with the Bath AS Disease Activity Index (BASDAI), Bath AS Functional Index (BASFI), C-reactive protein, and erythrocyte sedimentation rate as the dependent variables and different stratification of smoking duration, smoking intensity, and cumulative smoking as independent variables. In order to compare our results with previous studies, meta-analysis was performed to calculate standardized mean difference (SMD) for relationship between outcomes and smoking status. A total of 1178 AS patients were analyzed. Compared with non-smokers, the risk of having active disease (BASDAI ≥ 4) was higher in patients who smoked at least 15 years, or 15 cigarettes per day, or 15 pack-years (OR = 1.70 [1.06, 2.73], 1.75 [1.08, 2.82], and 1.97 [1.06, 3.67], respectively); and smokers had increasing risk of BASDAI ≥ 4 with increasing years of smoking, or cigarettes per day, or pack-years (p_-trend = 0.010, 0.008 and 0.006, respectively). The risk of having active disease was higher in patients who smoked at least 15 cigarettes per day or 15 pack-years (OR = 1.74 [1.06, 2.84] and 2.89 [1.56, 5.35], respectively), with increasing number of cigarettes per day and pack-years. Smokers had an increased risk of BASFI ≥ 4 (p_-trend = 0.040 and 0.007, respectively). By meta-analysis, current, former and ever smokers had significantly higher BASDAI (SMD = 0.34 [0.18, 0.48], 0.10 [0.01, 0.19], and 0.27 [0.20, 0.34], respectively) and BASFI (SMD = 0.35 [0.16, 0.55], 0.30 [0.22, 0.39], and 0.35 [0.21, 0.50], respectively) compared to non-smokers. Smoking is a risk factor for greater disease activity and worse functioning in AS patients.

Hyperuricemia in Asian psoriatic arthritis patients

AIM

It is generally accepted that hyperuricemia is commonly associated with psoriatic arthritis (PsA). However, variations in ethnicity, diet and habitat may contribute to differences in prevalence and risk factors for hyperuricemia in PsA patients. Moreover, Asian specific data is deficient. The primary objective of the present study was to determine the prevalence of hyperuricemia among PsA patients. The secondary objective was to explore its associated risk factors.

METHODS

This was a multi-center, cross-sectional observational study of 160 PsA patients from local Rheumatology clinics. Serum uric acid (SUA) level and other clinical parameters were measured and hyperuricemia was defined as SUA level greater or equal to 360 umol/L in females and 420 umol/L in males.

RESULTS

Forty-nine of 160 patients (30.6%) had hyperuricemia, of which 32 were men, 17 were women. Among those with hyperuricemia, mean SUA level was 500.7 ± 95.9 umol/L and 427.8 ± 83.1 umol/L in males and females, respectively. Univariate analysis found: (i) overweight status; (ii) obesity; (iii) Psoriasis Area and Severity Index; (iv) body surface area; (v) severe skin involvement, as being potentially associated with hyperuricemia. Regression model identified overweight status increased the likelihood of hyperuricemia in PsA, with an odds ratio of 4.4 (95% CI: 2.0-9.5). Furthermore, there was moderately positive correlation (r = 0.37) between body mass index (BMI) and SUA level. No associations were found between arthritis conditions and duration, lipid profile, creatinine clearance; and hyperuricemia.

CONCLUSION

A significant proportion of PsA patients had asymptomatic hyperuricemia. It was closely related with BMI, which represented metabolic dysregulation; but not with severity of skin disease, joint involvement or renal function.

Treat to Target in Axial Spondyloarthritis: What Are the Issues?

PURPOSE OF THE REVIEW

Treat to Target (T2T) strategy has been widely used in the management of chronic medical conditions, such as hypertension, diabetes, and hypothyroidism, as well as rheumatic diseases, such as rheumatoid arthritis and gout. The purpose of this review is to discuss the importance, feasibility, and challenges in adopting the T2T strategy for the management of axial spondyloarthritis (axSpA).

RECENT FINDINGS

In 2014, a panel of international experts published recommendations for T2T in axSpA. Recent Tight Control of Inflammation in Early Psoriatic Arthritis (TICOPA) trial demonstrated efficacy of T2T in the management of the psoriatic arthritis. However, there are several issues in the adoption of T2T in axSpA. They include lack of evidence of the impact of aggressive management on clinical and radiographic outcomes in axSpA and unavailability of a definite target for the treatment, as well as limited therapeutic options. In this review, we discuss the intricacies of the T2T strategy in axSpA. We need more clinical evidence in the form of randomized clinical studies to assess the impact of T2T on outcomes in axSpA. We also need a definite target which is useful in the routine clinical practice, as well as for clinical trials.

Quebec Serve and Protect Low Back Pain Study: A Web-based Cross-sectional Investigation of Prevalence and Functional Impact Among Police Officers

STUDY DESIGN

Web-based cross-sectional study.

OBJECTIVE

The aim of this study was to describe the prevalence and the burden of low back pain (LBP) and chronic low back pain (CLBP) among Quebec police officers.

SUMMARY OF BACKGROUND DATA

Police officers have work-related factors associated with LBP, but chronicity and impacts of this condition have been little explored among this population.

METHODS

Between May and October 2014, a web-based cross-sectional study was conducted among police officers working in the province of Quebec (Canada). Nine police organizations accepted to disseminate the email invitation to their members. The survey included the French-Canadian version of the Nordic Musculoskeletal Questionnaire and other items regarding functional impact of LBP and associated treatments.

RESULTS

A total of 3589 police officers completed the questionnaire. Mean age was 38.5 ± 8.7 years, 32.0% were women, and 67.4% reported being car-patrol officers. A majority reported LBP symptoms in the past 12 months (67.7%) and 96.5% of them perceived that presence of LBP was totally/partially linked to their work in the police force. Prevalence of CLBP among all responders was 28.7%. Police officers reporting CLBP, as compared to those reporting acute or subacute LBP symptoms in the past 12 months, were more likely to report LBP-related reduction of work activities (64.4% vs. 45.7%; P < 0.001) and more working days lost in the past 12 months (average of 11.9 ± 43.5 vs. 1.5 ± 9.8; P < 0.001). A greater proportion also reported LBP-related health care visits in the past 12 months (86.2% vs. 64.2%; P < 0.001) and current use of pain medications/complementary alternative medicines (90.1% vs. 69.7%; P < 0.001).

CONCLUSION

CLBP is a frequent and burdensome condition among Quebec police officers. Our results underline the importance for police organizations to promote CLBP prevention and to implement workplace management programs.

LEVEL OF EVIDENCE

3.

Pain problems for patients with mild and moderate chronic obstructive pulmonary disease - a community-based study in Shanghai

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a great public health burden worldwide. Few studies have focused on pain problems in patients with mild and moderate COPD in Chinese community settings.

METHODS

A cross-sectional study of 283 patients with mild and moderate COPD was conducted in six communities that were randomly sampled in Pudong New Area of Shanghai, China, in 2016. A face-to-face interview was conducted to collect data on personal characteristics and health conditions. The short form McGill Pain Questionnaire and the COPD assessment test (CAT) were applied to evaluate pain problems and health status, respectively.

RESULTS

Among 283 subjects, more than one third (37%) had pain problems indicated by the present pain intensity (PPI) scale. COPD patients aged <65 years with exacerbation in the past 12 months or a CAT score of ≥10 had a significantly higher score in affective dimension. Female sex, COPD severity, and length of disease were significantly related to higher scores of the sensory dimension. Those with moderate COPD or a CAT score of ≥10 had significantly higher scores of visual analog scale than those with mild COPD or a CAT score <10. Patients with moderate COPD had a higher rank of PPI than those with mild COPD.

CONCLUSION

Pain was common in patients with mild and moderate COPD in the community settings of Shanghai, China. Severity of COPD and CAT score were significantly related to the prevalence of pain. Intervention measures should be developed to improve pain problems for COPD patients.

A Multi-centered Cross-sectional Study of Disease Burden of Pain of Inpatients in Southwest China

Background:

Pain is a common burden of disease globally; yet, it is not systematically investigated in China, especially in hospitalized patients. This study was aimed at clarifying the epidemiological characteristics of pain and related factors in hospitalized patients in Southwest China.

Methods:

A cross-sectional study was conducted to investigate the prevalence, severity, and influencing factors of pain and modes of postoperative analgesia in hospitalized patients from 17 hospitals in Southwest China. A prevalidated questionnaire was employed to calibrate all of these items within 3 days from March 18, 2015 to March 20, 2015.

Results:

A total of 2293 patients were surveyed, the incidence of pain was 57.4% in all hospitalized patients at rest, of which 62.1% were with acute pain and 37.9% had persistent to chronic pain. Among surgical patients, 90.8% of them complained of acute postoperative pain at rest and 97.1% in motion. The incidence of acute postoperative moderate-to-severe pain was 28.8% at rest and 45.1% in motion. Surgical patients reported higher incidences of pain, especially acute and persistent pain compared with nonsurgical patients (P < 0.05). Postoperative pain occurred predominately at surgical sites (95.2%) as compared with nonsurgical sites (4.8%). Agedness, lower education level, surgery, and history of smoking were factors associated with increased duration and severity of postoperative pain and nonsurgical pain (P < 0.05).

Conclusions:

Pain is a common burden of disease in China, of which surgical pain constituted an important component. Surgical patients complained more severe pain than those who did not undergo surgery. Postoperative analgesia still needs to be improved to control pain after surgery. Patients' perception might influence the efficacy of pain management, which should be implemented with a multidisciplinary approach.

The effect of total hip replacement on employment in patients with ankylosing spondylitis

Although total hip replacement (THR) has been proven to be effective, the effect of THR on employment in ankylosing spondylitis (AS) in Chinese population is still unknown. We aimed to demonstrate whether or not patients with AS returned to work following THR and factors associated with the work ability after THR. We performed a retrospective study including a total number of 128 AS patients undergoing THR between 2009 and 2013. Presurgery and postsurgery data including disease state, work status, type of job, and time of resuming work were collected. Factors associated with early return to work were assessed through ordinal regression. Eighty-seven of 128 patients (68 %) were employed within 1 year before THR and 98 returned to work after surgery. Among them, 21, 46, and 31 resumed work by 3, 6, and 12 months postoperation, respectively. Multivariate ordinal regression showed that patients with unilateral THR, younger age, lower BASFI score, employed presurgery, and low or moderate physical demand were more likely to resume work earlier. Most individuals working presurgery returned to work after THR. For young AS patients with hip involvement, THR is an effective treatment for improving and maintaining work ability.

Global Prevalence of Spondyloarthritis: A Systematic Review and Meta-Regression Analysis

OBJECTIVE

To summarize the prevalence of spondyloarthritis (SpA) and its subtypes in the general population, and to identify demographic and methodologic characteristics that might explain heterogeneity in prevalence estimates.

METHODS

A systematic literature search was performed to identify relevant articles. Risk of bias was assessed and data were extracted. Pooled prevalences were calculated. Potential sources of heterogeneity were explored by subgroup analysis and meta-regression analysis.

RESULTS

The prevalence of SpA ranged from 0.20% (95% confidence interval [95% CI] 0.00-0.66) in South-East Asia to 1.61% (95% CI 1.27-2.00) in Northern Arctic communities; the prevalence of ankylosing spondylitis (AS) from 0.02% (95% CI 0.00-0.21) in Sub-Saharan Africa to 0.35% (95% CI 0.24-0.48) in Northern Arctic communities; and the prevalence of psoriatic arthritis (PsA) from 0.01% (95% CI 0.00-0.17) in the Middle East to 0.19% (95% CI 0.16-0.32) in Europe. The following characteristics were significantly associated with variation in prevalence of SpA, AS, and/or PsA: proportion of females, mean age of the sample, geographic area and setting (demographic characteristics), year of data collection, case finding, and case ascertainment (methodologic characteristics). For the other SpA subgroups, too few studies were available to conduct a meta-analysis, but prevalence estimates of reactive arthritis (range 0.0-0.2%), SpA related to inflammatory bowel disease (range 0.0-0.1%), and undifferentiated SpA (range 0.0-0.7%) were generally low.

CONCLUSION

SpA is a common disease, but with large variation in reported prevalence estimates, which can partly be explained by differences in demographic and methodologic characteristics. Particularly, geographic area as well as case finding account for a substantial part of the heterogeneity.

Review for Disease of the Year: Epidemiology of HLA-B27 Associated Ocular Disorders

Acute anterior uveitis is generally recognized as the most common form of uveitis. An association with HLA-B27 is seen in approximately half of cases of acute anterior uveitis. The prevalence of HLA-B27 varies widely between ethnic populations, with an approximate 8-10% prevalence in non-Hispanic whites and lower prevalence in Mexican- (4%) and African- (2-4%) Americans. A group of systemic inflammatory diseases, the spondyloarthropathies, similarly demonstrates a strong association with HLA-B27. The strength of association varies, depending on the specific spondyloarthropathy, with the strongest association found in patients with ankylosing spondylitis. The majority of patients with HLA-B27 associated uveitis will have an underlying spondyloarthropathy. Suspicion for HLA-B27 associated uveitis should prompt a careful clinical history to assess for features of a spondyloarthropathy as the characteristics of any associated uveitis may vary.

Challenges of diagnosis and management of axial spondyloarthritis in North Africa and the Middle East: An expert consensus

Axial spondyloarthritis (SpA) is a spectrum of inflammatory disease with stages characterized by both nonradiographic and radiographic sacroiliitis. Nonradiographic axial SpA is associated with health-related quality-of-life impairment and may progress to ankylosing spondylitis. Axial SpA has a low prevalence in some countries in North Africa and the Middle East, and pooling of data and resources is needed to increase understanding of the regional picture. Early diagnosis and effective treatment are required to reduce disease burden and prevent progression. Anti-TNF therapy is recommended for patients with persistently high disease activity despite conventional treatment, and has been shown to be effective in patients without radiographic damage. Diagnostic delays can be an obstacle to early treatment and appropriate referral strategies are needed. In some countries, restricted access to magnetic resonance imaging and anti-TNF agents presents a challenge. In this article, a group of experts from North Africa and the Middle East evaluated the diagnosis and management of axial SpA with particular reference to this region.

Emerging drugs for psoriatic arthritis

INTRODUCTION

The majority of Psoriatic Arthritis patients experience a good clinical response to anti-Tumor Necrosis Factor (TNF)-α therapies. However, treatment failure with anti-TNF-α can represent a relevant clinical problem.

AREAS COVERED

We review the efficacy and safety profile of biological therapies that have been reported from randomized, controlled trials in phase II and phase III available in Pubmed Database for agents targeting IL-12/23p40 antibody (ustekinumab) and IL-17 (secukinumab), inhibitor of phosphodiesterase 4, (apremilast), and of JAK/STAT pathways (tofacitinib) and CTLA4 co-stimulation (abatacept) in Psoriatic Arthritis.

EXPERT OPINION

In Psoriatic Arthritis, main emerging drugs are represented by the fully human monoclonal IL-12/23p40 antibody, ustekinumab, the agent targeting IL-17, secukinumab, and the inhibitor of phosphodiesterase 4, apremilast. Results on T cell co-stimulation inhibition by abatacept are insufficient both in psoriasis and in PsA. In vitro investigations on JAK/STAT pathways in PsA suggest that tofacitinib could represent a further valuable therapeutic option. Emerging biological treatments other than anti-TNF agents, ustekinumab, secukinumab and apremilast appear promising for Psoriatic Arthritis and recent studies have showed a good efficacy and an acceptable safety profile; however, further and long-term studies are advocated.

Prevalence of chronic low back pain: systematic review

OBJECTIVE

To estimate worldwide prevalence of chronic low back pain according to age and sex.

METHODS

We consulted Medline (PubMed), LILACS and EMBASE electronic databases. The search strategy used the following descriptors and combinations: back pain, prevalence, musculoskeletal diseases, chronic musculoskeletal pain, rheumatic, low back pain, musculoskeletal disorders and chronic low back pain. We selected cross-sectional population-based or cohort studies that assessed chronic low back pain as an outcome. We also assessed the quality of the selected studies as well as the chronic low back pain prevalence according to age and sex.

RESULTS

The review included 28 studies. Based on our qualitative evaluation, around one third of the studies had low scores, mainly due to high non-response rates. Chronic low back pain prevalence was 4.2% in individuals aged between 24 and 39 years old and 19.6% in those aged between 20 and 59. Of nine studies with individuals aged 18 and above, six reported chronic low back pain between 3.9% and 10.2% and three, prevalence between 13.1% and 20.3%. In the Brazilian older population, chronic low back pain prevalence was 25.4%.

CONCLUSIONS

Chronic low back pain prevalence increases linearly from the third decade of life on, until the 60 years of age, being more prevalent in women. Methodological approaches aiming to reduce high heterogeneity in case definitions of chronic low back pain are essential to consistency and comparative analysis between studies. A standard chronic low back pain definition should include the precise description of the anatomical area, pain duration and limitation level.

Psoriatic arthritis: Epidemiology, diagnosis, and treatment

Our understanding of psoriatic arthritis has evolved as new knowledge of the disease has emerged. However, the exact prevalence of psoriatic arthritis is unknown, and its pathogenesis has not been fully elucidated. Genetic, environmental, and immunologic factors have all been implicated in disease development. Early diagnosis and treatment have become primary objectives in clinical rheumatology. Psoriatic arthritis not only causes functional impairment, but also increases mortality risk of patients. The advent of new therapeutic agents capable of arresting the progression of joint damage is expected. However, early psoriatic arthritis assessment remains limited. The objectives of this article are to outline the epidemiology, diagnosis, and treatment of psoriatic arthritis and to suggest a paradigm for identifying early psoriatic arthritis patients.

Epidemiology of spondyloarthritis: a review

The classification of Spondyloarthritis (SpA) has been revised with the introduction of the ASAS classification criteria. Although this has best been described in ankylosing spondylitis and psoriatic arthritis, there are population studies evaluating the epidemiology of the different subgroups of SpA. In this paper, we present data on the incidence and prevalence of the subgroups of SpA in different populations, and point to data indicating how the introduction of new classification criteria, with the altered perception of the SpA entity, might impact on the epidemiology.

Global prevalence of ankylosing spondylitis

OBJECTIVES

For effective health care provision, knowledge of disease prevalence is paramount. There has been no systematic endeavour to establish continent-based AS estimates, however, prevalence is thought to vary by country and background HLA-B27 prevalence. This study aimed to estimate AS prevalence worldwide and to calculate the expected number of cases.

METHODS

A systematic literature search was conducted. Prevalence data were extracted and used to calculate the mean prevalence by continent and the expected number of cases based on country-specific prevalence (or, if missing, the prevalence from neighbouring countries). A second estimate was made using the prevalence from countries with similar HLA-B27 prevalences if a country-specific prevalence estimate was not available.

RESULTS

The mean AS prevalence per 10,000 (from 36 eligible studies) was 23.8 in Europe, 16.7 in Asia, 31.9 in North America, 10.2 in Latin America and 7.4 in Africa. Additional estimates, weighted by study size, were calculated as 18.6, 18.0 and 12.2 for Europe, Asia and Latin America, respectively. There were sufficient studies to estimate the number of cases in Europe and Asia, calculated to be 1.30-1.56 million and 4.63-4.98 million, respectively.

CONCLUSION

This study represents the first systematic attempt to collate estimates of AS prevalence into a single continent-based estimate. In addition, the number of expected cases in Europe and Asia was estimated. Through reviewing the current literature, it is apparent that the continuing conduct of epidemiological studies of AS prevalence is of great importance, particularly as diagnostic capabilities improve and with the recent development of the criteria for axial SpA.

Comparison of two referral strategies for diagnosis of axial spondyloarthritis: the Recognising and Diagnosing Ankylosing Spondylitis Reliably (RADAR) study

OBJECTIVE

To determine which of two referral strategies, when used by referring physicians for patients with chronic back pain (CBP), is superior for diagnosing axial spondyloarthritis (SpA) by rheumatologists across several countries.

METHODS

Primary care referral sites in 16 countries were randomised (1 : 1) to refer patients with CBP lasting >3 months and onset before age 45 years to a rheumatologist using either strategy 1 (any of inflammatory back pain (IBP), HLA-B27 or sacroiliitis on imaging) or strategy 2 (two of the following: IBP, HLA-B27, sacroiliitis, family history of axial SpA, good response to non-steroidal anti-inflammatory drugs, extra-articular manifestations). The rheumatologist established the diagnosis. The primary analysis compared the proportion of patients diagnosed with definite axial SpA by referral strategy.

RESULTS

Patients (N=1072) were referred by 278 sites to 64 rheumatologists: 504 patients by strategy 1 and 568 patients by strategy 2. Axial SpA was diagnosed in 35.6% and 39.8% of patients referred by these respective strategies (between-group difference 4.40%; 95% CI -7.09% to 15.89%; p=0.447). IBP was the most frequently used referral criterion (94.7% of cases), showing high concordance (85.4%) with rheumatologists' assessments, and having sensitivity and a negative predictive value of >85% but a positive predictive value and specificity of <50%. Combining IBP with other criteria (eg, sacroiliitis, HLA-B27) increased the likelihood for diagnosing axial SpA.

CONCLUSIONS

A referral strategy based on three criteria leads to a diagnosis of axial SpA in approximately 35% of patients with CBP and is applicable across countries and geographical locales with presumably different levels of expertise in axial SpA.

Epidemiology of spondyloarthritis

Spondyloarthritis (SpA) represents a group of interrelated diseases with common clinical features and a close association with HLA-B27. Reports of incidence and prevalence of diseases vary depending on methodological differences between studies, the case definition used to classify disease, and the prevalence of HLA-B27 in the population studied. Newly proposed criteria for axial SpA and peripheral SpA present a new approach to facilitate classification of the SpA into 2 main subtypes and the criteria allow earlier detection of patents with inflammatory back pain. These criteria were developed for use in a (specialized) clinical setting and not for large epidemiologic studies.