Background Uveitis, psoriasis and inflammatory bowel disease (IBD) are common extra-articular manifestations (EAMs) in patients with ankylosing spondylitis (AS); however, summary data of reported prevalence rates are lacking.
Objectives To systematically review the published literature on the prevalence of the common EAMs among patients with AS and to explore sources of heterogeneity.
Methods A systematic literature search was performed (Medline, Embase and Cochrane Library). Risk of bias was assessed. Crude and pooled prevalence rates with 95% confidence intervals (CI) were calculated. Potential sources of any observed clinical or methodological heterogeneity in the estimates were explored by subgroup- and meta-regression analysis, including disease duration, percentage of HLA-B27 positive patients, geographic area, sampling frame of patients and method of ascertainment of the EAMs.
Results From the 156 selected articles, 143 reported the prevalence of uveitis (44372 patients), 56 of psoriasis (27626 patients) and 69 of IBD (30410 patients). Substantial heterogeneity was observed in prevalence estimates among all EAMs (I2=84-95%). The pooled prevalence rate of uveitis was 25.9% (95% CI 24.2-27.7), and was significantly associated with disease duration (increasing from 17.6% in studies including patients with a mean disease duration <10 years to 31.6% in those with a duration >20 years); geographic area (highest in studies from Europe (29.4%) and North-America (35.3%) and lower in studies from Asia (21.0%) and Latin-America (20.2%)); and method of ascertainment (highest for self-report (35.9%)). In the final multivariable model, disease duration (OR 1.05, 95% CI 1.05-1.08) and geographic area remained significantly associated with the prevalence of uveitis. The pooled prevalence rate of psoriasis was 9.3% (95% CI 8.1-10.6) and was in uni- and multivariable analysis only associated with geographic area, with highest rates in studies from Europe (10.9%) and lowest rates in studies from Asia (3.7%) and the Middle-East (4.2%). The pooled prevalence rate of IBD was 6.8% (95% CI 6.1-7.7) and was significantly associated with the proportion of females in the studies (OR 1.01, 95% CI 1.00-1.03) and geographic area (highest prevalence in Latin-America (9.6%) and lowest in Asia (2.9%)).
Conclusions EAMs are common in patients with AS but reported prevalence rates are dependent on clinical- and methodological characteristics of the studies.
Disclosure of Interest None Declared