Presentation of enthesitis-related arthritis and juvenile-onset spondyloarthritis: a cross-sectional study in a pediatric and adult clinic.

BACKGROUND: Juvenile idiopathic arthritis (JIA) comprises a whole spectrum of chronic arthritis starting before 16 years of age. The study aims to explore the clinical and demographic descriptors, treatment, and disease progression of enthesitis-related arthritis (ERA) in comparison with juvenile-onset spondyloarthritis (SpA). METHODS: Cross-sectional analysis of consecutive patients in two dedicated clinics, with a single visit and retrospective case-notes review. Arthritis, enthesitis and sacroiliitis were evaluated by scoring disease activity and damage. Continuous variables were reported by median, interquartile range; categorical variables were reported by the frequency comparison of the two groups. RESULTS: Thirty-three cases were included, being 23 (69.7%) with ERA. The median age at diagnosis was 12.5 y (SpA) vs. 9 y (ERA) (p < 0.01); the time from symptom onset to diagnosis was 5.5 y (SpA) vs. 1.5 y (ERA) (p < 0.03). In both groups, the predominant presentation was a single joint or < 5 lower limb joints and asymmetric involvement, with a high frequency of enthesitis. There was a higher frequency of mid-tarsal and ankle synovitis in the ERA group and hip involvement in those with SpA. The comparison of the frequency of spine symptoms at presentation, 30% SpA vs. 21.7% ERA (p = 0.7), was not significant, and radiographic progression to spinal involvement occurred in 43.5% of ERA patients. The median time for spinal progression and age at onset was 2.2 and 12 y for ERA, and 4 and 16.5 y for SpA, respectively. Activity and damage scores were not significantly different between the groups. Treatment comparison resulted in 91.3% of ERA and 100% SpA being treated, predominantly with NSAIDs in both groups, followed by DMARDs and biologics, with a higher frequency of biologics in SpA. CONCLUSION: The main differences were the late diagnoses of SpA, and the hip and spine involvement, with higher frequency of biologic treatment in juvenile-onset SpA compared to ERA.

The prevalence of chronic obstructive pulmonary disease in patients with spondyloarthritis compared to the general population in the southernmost region of Sweden: a case-control study.

Spondyloarthritis (SpA) has been associated with comorbidities, e.g., cardiovascular disease. However, little is known about the relation between SpA and chronic obstructive pulmonary disease (COPD). The aim of the study was to compare the prevalence of COPD in SpA to the general population. Patients with prevalent SpA in Skåne, Sweden, on December 31, 2018, were identified based on diagnostic codes in a regional register on primary care, secondary outpatient care and inpatient care. Population-based controls (5 per SpA case) were matched for age, sex and municipality. The base case definition for COPD required at least two prior visits with a registered COPD diagnosis. Stricter definitions included dispensed prescriptions for COPD and a COPD diagnosis made by a specialist in lung medicine. The prevalence of COPD in patients with SpA and controls, overall and stratified by sex and age, and the corresponding prevalence ratios, were estimated. A total of 3571 patients with SpA (51% male, mean age 53 years) were compared to 17,855 matched controls. The prevalence of COPD in patients with SpA was 37.8/1000, with a prevalence ratio compared to controls of 1.03 (95% CI 0.85-1.24). There were no significant differences in COPD prevalence between patients with SpA and controls in men or women, in any of the age groups, or in analyses using stricter definitions of COPD. In this regional study including data from primary care, the prevalence of COPD was not increased in patients with SpA compared to the background population.

Factors associated with acute anterior uveitis history in patients with axial spondyloarthritis: Results of a longitudinal study.

BACKGROUNDS: Acute anterior uveitis (AAU) is the most common extra-musculoskeletal manifestation in axial spondyloarthritis (axSpA). OBJECTIVES: The aim of the study is to evaluate the factors associated with AAU attacks in patients with axSpA during a 36-month follow-up period. METHODS: In total, 469 patients with axSpA were included in this observational study. Demographic data, clinical characteristics, disease activity measurements, and treatment patterns were compared between patients with and without a history of AAU. The development of AAU and its related factors were investigated using generalized estimating equations, which is a technique for longitudinal data analysis. RESULTS: Overall, 99 (21%) out of 469 patients experienced at least one AAU attack, with 77 patients (78%) having a history of AAU and 53 patients (58% of whom had a history of AAU) experiencing AAU attacks during the follow-up period. At baseline, patients with a history of AAU were found to be older (p = .001), be more likely to have peripheral arthritis (p < .001), have higher serum CRP levels (p = .016), have a higher frequency of sulfasalazine (SLZ) and tumor necrosis factor inhibitors (TNFi) use (p < .001 and p < .001, respectively). In the longitudinal analysis, having a history of AAU was identified as the only independent determinant of the development of AAU. CONCLUSIONS: AAU history might be a risk factor for the development of AAU attacks in patients with axSpA. Although TNFi and SLZ were prescribed more frequently to patients with a history of AAU, the effectiveness of these agents in preventing further AAU attacks was not demonstrated.

The prevalence of sarcopenia in spondyloarthritis patients: a meta-analysis.

BACKGROUND: Spondyloarthritis (SpA) is a chronic inflammatory disorder that affects sacroiliac joints and spine, resulting in substantial disability. Sarcopenia, characterized by the loss of muscle mass and function, is a prevalent comorbidity in various chronic diseases. However, the exact prevalence of sarcopenia in SpA patients remains uncertain. The objective of this study is to conduct a systematic review and meta-analysis of the available literature to determine the prevalence of sarcopenia in SpA. METHODS: A comprehensive search was conducted in EMBASE, MEDLINE, WEB OF SCIENCE, and COCHRANE databases to identify relevant studies published up to 2023. Studies investigating the prevalence of sarcopenia in SpA patients were included. Data on study characteristics, participant demographics, diagnostic criteria for sarcopenia, and prevalence rates were extracted. Meta-analysis was performed using a random-effects model to estimate the overall prevalence of sarcopenia in SpA patients. RESULTS: A total of 16 studies that met the inclusion criteria were included in the systematic review. These studies encompassed a combined sample size of 999 patients with SpA. The meta-analysis findings revealed that the overall prevalence of sarcopenia in SpA patients was 25.0% (95% confidence interval: 0.127 to 0.352). Furthermore, the prevalence of presarcopenia and severe sarcopenia was found to be 21.0% and 8.7%, respectively. Subgroup analysis was conducted to examine different diagnostic criteria, subtypes, and sex of SpA in relation to sarcopenia. CONCLUSION: This systematic review and meta-analysis provide a comprehensive overview of the prevalence of sarcopenia in SpA patients. The findings suggest a high prevalence of sarcopenia in SpA patients, emphasizing the need for targeted interventions to prevent and manage sarcopenia. And further research is needed to explore the underlying mechanisms and potential therapeutic strategies for sarcopenia in SpA.

Barriers and facilitators in diagnosing axial spondyloarthritis: a qualitative study.

INTRODUCTION: Diagnosis of axial spondyloarthritis (axSpA) is frequently delayed for years after symptom onset. However, little is known about patient and healthcare professional (HCP) perspectives on barriers and facilitators in axSpA diagnosis. This study explored the experiences and perceptions of both groups regarding the factors affecting the timely diagnosis of axSpA. METHOD: Semi-structured interviews with patients with axSpA and axSpA-interested HCPs from the United Kingdom (UK) were performed by telephone or Microsoft Teams and focussed on the individuals' perspective of the diagnostic journey for axSpA. Interview transcripts were thematically analysed. RESULTS: Fourteen patients with axSpA (10 female, 4 male) and 14 UK based HCPs were recruited, the latter comprising of 5 physiotherapists, 4 General Practitioners, 3 rheumatologists, a nurse, and an occupational therapist. Barriers to diagnosis identified by patients and HCPs were: difficult to diagnose, a lack of awareness, unclear referral pathways, patient behaviour and patient/HCP communication. Patient-identified facilitators of diagnosis were patient advocacy, clear referral processes and pathways, increased awareness, and serendipity. HCPs identified promoting awareness as a facilitator of diagnosis, along with symptom recognition, improvements to healthcare practice and patient/HCP communications. CONCLUSION: Poor communication and a lack of understanding of axSpA in the professional and public spheres undermine progress towards timely diagnosis of axSpA. Improving communication and awareness for patients and HCPs, along with systemic changes in healthcare (such as improved referral pathways) could reduce diagnostic delay.

The management of patients with inflammatory bowel disease-associated spondyloarthritis: Italian Group for the Study of Inflammatory Bowel Disease (IG-IBD) and Italian Society of Rheumatology (SIR) recommendations based on a pseudo-Delphi consensus.

Spondyloarthritis (SpA) is the most frequent extraintestinal manifestation in patients with inflammatory bowel diseases (IBD). When IBD and spondyloarthritis coexist, musculoskeletal and intestinal disease features should be considered when planning a therapeutic strategy. Treatment options for IBD and SpA have expanded enormously over the last few years, but randomized controlled trials with specific endpoints focused on SpA are not available in the IBD setting. To address this important clinical topic, the Italian Group for the Study of Inflammatory Bowel Disease (IG-IBD) and the Italian Society of Rheumatology (SIR) jointly planned to draw updated therapeutic recommendations for IBD-associated SpA using a pseudo-Delphi method. This document presents the official recommendations of IG-IBD and SIR on the management of IBD-associated SpA in the form of 34 statements and 4 therapeutic algorithms. It is intended to be a reference guide for gastroenterologists and rheumatologists dealing with IBD-associated SpA.

Comparative Effectiveness of Tofacitinib and Adalimumab in Axial Spondyloarthritis: A Real-World Clinical Context Multicenter Study.

INTRODUCTION: Tofacitinib, an oral Janus kinase inhibitor, is a putative choice in the treatment of axial spondyloarthritis (AxSpA). The objective of this study was to compare the effectiveness and tolerability of tofacitinib with adalimumab, in AxSpA, in a real-world clinical setting. METHODS: In this multicentric medical records review study, adult patients with active AxSpA treated with either tofacitinib 5 mg twice daily or adalimumab 40 mg subcutaneously fortnightly were recruited. Effectiveness was measured with Ankylosing Spondylitis Disease Activity Score (ASDAS) and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). Drug-cost analysis was calculated with Incremental Cost-Effectiveness Ratio (ICER drug ). RESULTS: Among the 266 patients, 135 were treated with tofacitinib and 131 with adalimumab (follow-up: 6.5 ± 1.6 months). Mean improvement of BASDAI (3.39 ± 0.09 vs. 3.14 ± 1.16, respectively) and that of ASDAS (1.78 ± 0.68 vs. 2.07 ± 2.08, respectively) were comparable between the adalimumab and tofacitinib groups. A higher proportion of patients achieved BASDAI50 response in the second (49.5% vs. 31.6%) and fourth month (83.9% vs. 62.8%) and ASDAS low disease activity in the fourth month (71.6% vs. 47.9%) in the adalimumab group. All disease activity measurements were similar by the sixth month in both groups. A higher proportion of patients in the tofacitinib group than in the adalimumab group required change in therapy (14.8% vs. 7.6%, respectively). ICER drug for adalimumab compared with tofacitinib was US $188.8 per patient in the adalimumab group for each person-month with BASDAI <4. CONCLUSIONS: Tofacitinib showed comparable effectiveness with adalimumab in patients with AxSpA at the sixth month, despite lesser response in the initial months, with favorable ICER drug .

Change of perspective: impact of COVID-19 pandemic on axial spondyloarthritis-related web searches in Germany.

Several conventional cross-sectional studies have investigated the impact of the coronavirus disease (COVID-19) pandemic on patients with axial spondyloarthritis (axSpA) and reached contrary results regarding health and well-being. As analysis of web search data already provided insights into public interest and unmet needs, this study aimed to examine axSpA-related web searches before and during COVID-19 pandemic to gain a different perspective on the impact of COVID-19 on this disease. The Google Ads Keyword Planner was used to generate axSpA-related keywords and their monthly number of searches between June 2018 and November 2021 in Germany. These keywords were qualitatively classified into seven categories. A total of 538 axSpA-related keywords were used for the analysis. The number of axSpA-related searches increased during COVID-19 pandemic (before: n = 1,525,010 vs. during: n = 1,848,300), particularly searches for symptoms, disease outcomes, and causes, while interest in disease management and diagnosis decreased. This study demonstrated a shift in public interest in axSpA during COVID-19 in Germany and highlights an urgent expansion of telemedicine to be prepared for exceptional situations such as a pandemic.

Entry point of machine learning in axial spondyloarthritis.

Axial spondyloarthritis (axSpA) is a globally prevalent and challenging autoimmune disease. Characterised by insidious onset and slow progression, the absence of specific clinical manifestations and biomarkers often leads to misdiagnosis, thereby complicating early detection and diagnosis of axSpA. Furthermore, the high heterogeneity of axSpA, its complex pathogenesis and the lack of specific drugs means that traditional classification standards and treatment guidelines struggle to meet the demands of personalised treatment. Recently, machine learning (ML) has seen rapid advancements in the medical field. By integrating large-scale data with diverse algorithms and using multidimensional data, such as patient medical records, laboratory examinations, radiological data, drug usage and molecular biology information, ML can be modelled based on real-world clinical issues. This enables the diagnosis, stratification, therapeutic efficacy prediction and prognostic evaluation of axSpA, positioning it as an emerging research topic. This study explored the application and progression of ML in the diagnosis and therapy of axSpA from five perspectives: early diagnosis, stratification, disease monitoring, drug efficacy evaluation and comorbidity prediction. This study aimed to provide a novel direction for exploring rational diagnostic and therapeutic strategies for axSpA.

Validation of SPARCC MRI-RETIC e-tools for increasing scoring proficiency of MRI sacroiliac joint lesions in axial spondyloarthritis

BACKGROUND: The Spondyloarthritis Research Consortium of Canada (SPARCC) developers have created web-based calibration modules for the SPARCC MRI sacroiliac joint (SIJ) scoring methods. We aimed to test the impact of applying these e-modules on the feasibility and reliability of these methods. METHODS: The SPARCC-SIJ RETIC e-modules contain cases with baseline and follow-up scans and an online scoring interface. Visual real-time feedback regarding concordance/discordance of scoring with expert readers is provided by a colour-coding scheme. Reliability is assessed in real time by intraclass correlation coefficient (ICC), cases being scored until ICC targets are attained. Participating readers (n=17) from the EuroSpA Imaging project were randomised to one of two reader calibration strategies that each comprised three stages. Baseline and follow-up scans from 25 cases were scored after each stage was completed. Reliability was compared with a SPARCC developer, and the System Usability Scale (SUS) assessed feasibility. RESULTS: The reliability of readers for scoring bone marrow oedema was high after the first stage of calibration, and only minor improvement was noted following the use of the inflammation module. Greater enhancement of reader reliability was evident after the use of the structural module and was most consistently evident for the scoring of erosion (ICC status/change: stage 1 (0.42/0.20) to stage 3 (0.50/0.38)) and backfill (ICC status/change: stage 1 (0.51/0.19) to stage 3 (0.69/0.41)). The feasibility of both e-modules was evident by high SUS scores. CONCLUSION: The SPARCC-SIJ RETIC e-modules are feasible, effective knowledge transfer tools, and their use is recommended before using the SPARCC methods for clinical research and tria.

Neutrophile to lymphocyte and platelet to lymphocyte ratios predict clinical response to bDMARD in naïve spondylarthritis patients.

Objective: We aim to study association between neutrophile to lymphocyte (NLR) and platelet to lymphocyte (PLR) ratios and disease activity, and their value to predict bDMARD response. Methods: A set of spondylarthritis (SpA) patients under bDMARD registered in the Reuma.pt registry was studied. Sociodemographic, clinical and laboratorial variables were assessed on bDMARD initiation, 6, 12, 18 and 24 months (M) thereafter. Univariable and multivariable generalized estimation equations models assessed associations with disease activity. The NLR and PLR predictive value was assessed using univariable and multivariable logistic regression models. Results: A total of 170 patients were included. Most were male (54.7%), with a predominantly axial phenotype (84.7%). Significant associations were observed between NLR [B=1.55, 95% confidence interval (CI) = (1.38; 1.74)] and PLR [(B=1.16, 95% CI = (1.09; 1.24)] with ASDAS-CRP (p < 0.001). Both baseline ratios predicted ∆ ASDAS-CRP ≥ 1.1 at 6 months [OR = 2.20, 95% CI = (1.21, 4.00) for NLR; OR = 1.02, 95% CI = (1.01, 1.04) for PLR, p < 0.01)]. PLR was a significant predictor of ∆ ASDAS-CRP ≥ 1.1 in all timepoints [OR (12 M) = 1.02, 95% CI = (1.00, 1.03), p < 0.05; OR (18M) = 1.02, 95% CI = (1.01, 1.03), p < 0.001; OR (24M) = 1.01, 95% CI = (1.01, 1.02), p < 0.01]. Conclusion: NLR and PLR were associated with disease activity during the follow up of these patients. They seem to be significant predictors of therapeutic response to bDMARD in naïve SpA patients.

How to translate genetic findings into clinical applications in spondyloarthritis?

Spondyloarthritis (SpA) is characterized by a strong genetic predisposition evidenced by the identification of up to 50 susceptibility loci, in addition to HLA-B27, the major genetic factor associated with the disease. These loci have not only deepened our understanding of disease pathogenesis but also offer the potential to improve disease management. Diagnostic delay is a major issue in SpA. HLA-B27 testing is widely used as diagnostic biomarker in SpA but its predictive value is limited. Several attempts have been made to develop more sophisticated polygenic risk score (PRS). However, these scores currently offer very little improvement as compared to HLA-B27 and are still difficult to implement in clinical routine. Genetics might also help to predict disease outcome including treatment response. Several genetic variants have been reported to be associated with radiographic damage or with poor response to TNF blockers, unfortunately with lack of coherence across studies. Large-scale studies should be conducted to obtain more robust findings. Genetic and genomic evidence in complex diseases can be further used to support the identification of new drug targets and to repurpose existing drugs. Although not fully driven by genetics, development of IL-17 blockers has been facilitated by the discovery of the association between IL23R variants and SpA. Development of recent approaches combining GWAS findings with functional genomics will help to prioritize new drug targets in the future. Although very promising, translational genetics in SpA remains challenging and will require a multidisciplinary approach that integrates genetics, genomics, immunology, and clinical research.

MRI for axial SpA: Diagnosis, disease activity assessment, and recent advances.

Magnetic resonance imaging (MRI) is a sensitive imaging modality to detect early inflammatory changes in axial spondyloarthritis (SpA). Over a decade has passed since the inclusion of MRI assessment in the 2009 Assessment of SpondyloArthritis International Society (ASAS) classification criteria for axial SpA. Evidence and clinical experience of MRI in axial SpA have accumulated rapidly since. This has led to a better understanding of the clinical utility of MRI in early diagnosis, disease activity assessment, and monitoring of treatment response in axial SpA. Furthermore, technological advancements have paved the way for the development of novel MRI sequences for the quantification of inflammation and image optimization. The field of artificial intelligence has also been explored to aid medical imaging interpretation, including MRI in axial SpA. This review serves to provide an update on the latest understanding of the evolving roles of MRI in axial SpA.

Pre-assessment of patients with suspected axial spondyloarthritis combining student-led clinics and telemedicine: a qualitative study.

OBJECTIVE: Patients referred to rheumatologists are currently facing months of inefficient waiting time due to the increasing demand and rising workforce shortage. We piloted a pre-assessment of patients with suspected axial spondyloarthritis (axSpA) combining student-led clinics and telemedicine (symptom assessment, symptom monitoring and at-home capillary self-sampling) to improve access to rheumatology care. The aim of this study was to explore (1) current challenges accessing axSpA care and (2) patients' first-hand experiences. METHODS: Embedded within a clinical trial, this study was based on qualitative interviews with patients with suspected axSpA (n = 20). Data was analysed via qualitative content analysis. RESULTS: Student-led clinics were perceived as high-quality care, comparable to conventional rheumatologist-led visits. Patients expressed that their interactions with the students instilled a sense of trust. History-taking and examinations were perceived as comprehensive and meticulous. Telehealth tools were seen as empowering, offering immediate and continuous access to symptom assessment at home. Patients reported a lack of specificity of the electronic questionnaires, impeding accurate responses. Patients requested a comments area to supplement questionnaire responses. Some patients reported receiving help to complete the blood collection. CONCLUSION: Patients' access to rheumatology care is becoming increasingly burdensome. Pre-assessment including student-led clinics and telemedicine was highly accepted by patients. Patient interviews provided valuable in-depth feedback to improve the piloted patient pathway.

Can rheumatologists unequivocally diagnose axial spondyloarthritis in patients with chronic back pain of less than 2 years duration? Primary outcome of the 2-year SPondyloArthritis Caught Early (SPACE) cohort.

OBJECTIVES: To investigate the prevalence of axial spondyloarthritis (axSpA) in patients with chronic back pain (CBP) of less than 2 years (2y) duration referred to the rheumatologist, the development of diagnosis over time, and patient characteristics of those developing definite (d-)axSpA over 2y. METHODS: We analysed the 2y data from SPondyloArthritis Caught Early, a European cohort of patients (<45 years) with CBP (≥3 months, ≤2y) of unknown origin. The diagnostic workup comprised evaluation of clinical SpA features, acute phase reactants, HLA-B27, radiographs and MRI (sacroiliac joints and spine), with repeated assessments. At each visit (baseline, 3 months, 1y and 2y), rheumatologists reported a diagnosis of axSpA or non-axSpA with level of confidence (LoC; 0-not confident at all to 10-very confident). MAIN OUTCOME: axSpA diagnosis with LoC≥7 (d-axSpA) at 2y. RESULTS: In 552 patients with CBP, d-axSpA was diagnosed in 175 (32%) at baseline and 165 (30%) at 2y. Baseline diagnosis remained rather stable: at 2y, baseline d-axSpA was revised in 5% of patients, while 8% 'gained' d-axSpA. Diagnostic uncertainty persisted in 30%. HLA-B27+ and baseline sacroiliitis imaging discriminated best 2y-d-axSpA versus 2y-d-non-axSpA patients. Good response to non-steroidal anti-inflammatory drugs and MRI-sacroiliitis most frequently developed over follow-up in patients with a new d-axSpA diagnosis. Of the patients who developed MRI-sacroiliitis, 7/8 were HLA-B27+ and 5/8 male. CONCLUSION: A diagnosis of d-axSpA can be reliably made in nearly one-third of patients with CBP referred to the rheumatologist, but diagnostic uncertainty may persist in 5%-30% after 2y. Repeated assessments yield is modest, but repeating MRI may be worthwhile in male HLA-B27+ patients.

Comparison of the ASAS Health Index in patients classified as radiographic axial spondyloarthritis (axSpA) or non-radiographic axSpA in the ASAS Health Index international validation study.

OBJECTIVES: To determine if there were differences in the Assessment of SpondyloArthritis international Society Health Index (ASAS HI) scores between patients classified as radiographic axial spondyloarthritis (r-axSpA) and non-radiographic axSpA (nr-axSpA), and to identify factors associated with higher ASAS HI scores in both disease phenotypes. METHODS: This study was an ancillary analysis of the ASAS HI international validation project performed in 23 countries. Patients were included if they were ≥18 years of age and diagnosed with axSpA. Univariable and multivariable analysis were performed to determine if ASAS HI scores differed between the axSpA phenotypes, and to identify other variables associated with ASAS HI scores. We also tested for potential interactions between the axSpA phenotype and significant variables identified through the multivariable regression. RESULTS: A total of 976 patients were included, with 703 having r-axSpA and 273 nr-axSpA. Patients with r-axSpA reported higher (worse) ASAS HI scores compared with those with nr-axSpA (6.8 (4.4) vs 6.0 (4.0), p=0.02), but the axSpA phenotype was not associated with ASAS HI scores in the multivariable regression (ß: -0.19, 95% CI: -0.56 to 0.19). Female gender, having worse physical function (Bath Ankylosing Spondylitis Functional Index), disease activity (Ankylosing Spondylitis Disease Activity Score) and anxiety and depressive symptoms (Hospital Anxiety and Depression Scale) were associated with higher ASAS HI scores. No interactions were found to be significant. CONCLUSION: Overall health and functioning are similarly affected in patients with r-axSpA and nr-axSpA. Female patients, having worse physical function, disease activity, anxiety and depressive symptoms were independently associated with higher ASAS HI scores.

A Good Response to Nonsteroidal Antiinflammatory Drugs Does Not Discriminate Patients With Longstanding Axial Spondyloarthritis From Controls With Chronic Back Pain.

OBJECTIVE: To compare the response to nonsteroidal antiinflammatory drugs (NSAIDs) in patients with longstanding axial spondyloarthritis (axSpA) and controls with back pain (nonspondyloarthritis [non-SpA]). METHODS: Consecutive outpatients with chronic back pain (axSpA or non-SpA), were prospectively recruited. Any previous NSAIDs were withdrawn 2 days before study start (baseline). Back pain was assessed using a numerical rating scale (NRS; range 0-10) starting at 2 hours after baseline and several times thereafter up to 4 weeks. "Any response" to NSAIDs was defined as improvement of back pain on the NRS > 2 units, and "good response" as improvement > 50%, compared to baseline. RESULTS: Among 233 patients included, 68 had axSpA (29.2%) and 165 had non-SpA back pain (70.8%). The mean age was 42.7 (SD 10.7) vs 49.3 (SD 11.1) years, symptom duration 15.1 (SD 11.1) years vs 14.6 (SD 11.9) years, and pain score 5.9 (SD 2.3) vs 6.3 (SD 2.0), respectively. Overall, of patients with axSpA or non-SpA back pain, 30.9% vs 29.1% of patients showed any response and 23.5% vs 16.4% of patients showed a good response after 4 weeks, respectively (P value not significant). No differences were found in the rapidity of response or between subgroups of patients based on demographics, including different stages of axSpA. CONCLUSION: No major differences in the response to NSAIDs were found between patients with axSpA and those with non-SpA with longstanding chronic back pain. The item in the Assessment of SpondyloArthritis international Society classification criteria on "response to NSAIDs" needs more study.