ObjectivesUveitis, psoriasis and inflammatory bowel disease (IBD) are common extra-articular manifestations (EAM) in patients with ankylosing spondylitis (AS); however, summary data of reported prevalence are lacking. The aim of the present study was to summarise the prevalence of EAMs among patients with AS and to identify underlying factors to explain potential heterogeneity of prevalence.MethodsA systematic literature search was performed (Medline, Embase and Cochrane Library) to identify relevant articles. Risk of bias was assessed and data were extracted. Pooled prevalences were calculated. Potential sources of any observed clinical or methodological heterogeneity in the estimates were explored by subgroup and metaregression analysis.ResultsIn the 156 selected articles, 143 reported the prevalence of uveitis (44 372 patients), 56 of psoriasis (27 626 patients) and 69 of IBD (30 410 patients). Substantial heterogeneity was observed in prevalence estimates among all EAMs (I2=84–95%). The pooled prevalence of uveitis was 25.8% (95% CI 24.1% to 27.6%), and was positively associated in multivariable metaregression with disease duration (β 0.05, 95% CI 0.03 to 0.08) and random selection of patients (β −0.24, 95% CI −0.43 to −0.04). The pooled prevalence of psoriasis was 9.3% (95% CI 8.1% to 10.6%). The pooled prevalence of IBD was 6.8% (95% CI 6.1% to 7.7%) and was positively associated with the percentage of women in the studies (β 0.02, 95% CI 0.00 to 0.03). Geographical area was associated in multivariable metaregressions with prevalence of all EAMs.ConclusionsEAMs are common in patients with AS. The large heterogeneity between studies can be partly explained by differences in clinical as well as methodological characteristics.

Objectives: To analyse the long-term relationship between disease activity and radiographic damage in the spine in patients with ankylosing spondylitis (AS). Methods: Patients from the Outcome in AS International Study (OASIS) were followed up for 12 years, with 2-yearly clinical and radiographic assessments. Two readers independently scored the X-rays according to the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). Disease activity measures include the Bath AS Disease Activity Index (BASDAI), AS Disease Activity Index (ASDAS)-C-reactive protein (CRP), CRP, erythrocyte sedimentation rate (ESR), patient's global assessment and spinal pain. The relationship between disease activity measures and radiographic damage was investigated using longitudinal, autoregressive models with 2-year time lags. Results: 184 patients were included (70% males, 83% HLA-B27 positive, mean (SD) age 43 (12) years, 20 (12) years symptom duration). Disease activity measures were significantly longitudinally associated with radiographic progression. Neither medication nor the presence of extra-articular manifestations confounded this relationship. The models with ASDAS as disease activity measure fitted the data better than models with BASDAI, CRP or BASDAI+CRP. An increase of one ASDAS unit led to an increase of 0.72 mSASSS units/2 years. A 'very high disease activity state' (ie, ASDAS >3.5) compared with 'inactive disease' (ie, ASDAS <1.3) resulted in an additional 2-year progression of 2.31 mSASSS units. The effect of ASDAS on mSASSS was higher in males versus females (0.98 vs -0.06 mSASSS units per ASDAS unit) and in patients with <18 years vs >= 18 years symptom duration (0.84 vs 0.16 mSASSS units per ASDAS unit). Conclusions: This is the first study showing that disease activity contributes longitudinally to radiographic progression in the spine in AS. This effect is more pronounced in men and in the earlier phases of the disease

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.

Objectives: To describe the evolution of radiographic abnormalities of the spine in patients with ankylosing spondylitis (AS). Methods: Patients with AS were followed prospectively with 2 yearly radiographs for 12 years. The modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) was scored by two readers (R1 and R2). New syndesmophytes at uninvolved vertebral corners were computed. Radiographic progression was investigated using generalised estimating equations. Results: 809 radiographs (presenting 520 at 2 yearly intervals) from 186 patients (70% men, mean age 43 (SD 12) years, mean 20 (SD 12) years since symptom onset and 83% HLA-B27 positive) were included. Mean mSASSS at baseline was 11.6 (16.2). While the course of progression in individual patients was highly variable, and still occurred in patients with decades of symptom duration, mean 2 year progression was 2.0 (3.5) mSASSS units. Over the entire follow-up, at least one new syndesmophyte was found in 55% (R1) and 63% (R2) of patients (38% (R1) and 39% (R2) of all intervals). In 24% of patients (39% of intervals), there was no progression. A progression >= 5 mSASSS units occurred in 22% of patients (or in 12% of intervals). At the group level, a linear time course model fitted the data best, with a constant rate over the entire 12 year interval of 0.98 mSASSS units/year. Radiographic progression occurred significantly faster in men, in HLA-B27 positive patients and in patients with a baseline mSASSS >= 10. Conclusions: Long term radiographic progression in AS is highly variable in the individual patient, more severe in HLA-B27 positive men and still occurs after decades of disease. At the group level, however, progression in AS follows an approximately linear course