Background Extra-articular manifestations (EAMs), such as acute anterior uveitis (AAU), inflammatory bowel disease (IBD), and psoriasis contribute to the burden of the disease in patients with ankylosing spondylitis (AS).
Objectives To assess whether the presence of EAM is associated with more functional disability, quality of life (QoL), and radiographic damage in patients with AS over time.
Methods Twelve-year follow-up data from all patients included in the Outcome in Ankylosing Spondylitis International Study (OASIS) were used. The presence of EAMs was extracted from medical charts by two independent extractors. Function was assessed by the Bath AS Functional Index (BASFI). QoL was assessed by the Short Form-36 (SF-36), ASQoL and the EuroQoL. Radiographic damage was assessed by the modified Stoke AS Spinal Score (mSASSS). Univariable and multivariable generalized estimating equations (GEE) analyses were performed to assess whether prevalent and incident EAMs, respectively, were associated with function, QoL, and radiographic damage over time. Patients with a prevalent EAM were excluded from the analysis involving incident EAMs.
Results 216 Patients were included (154 (71%) men, mean age 43.6 years (SD 12.7), mean symptom duration 20.5 years (SD 11.7), and mean follow-up 8.3 years (SD 4.3). At baseline, 39 (18%) patients had AAU, 15 (7%) IBD, and 9 (4%) psoriasis (prevalent cases). During follow up, 19 patients developed AAU, 9 IBD, and 5 psoriasis (incident cases). Psoriasis was not taken into account in further analyses, because of a low prevalence and incidence in this cohort. Prevalent AAU was univariably associated with worse mSASSS (B=7.19, 95% Confidence Interval [95% CI] 0.19 to 14.19, p=0.04), and worse SF-36 mental component (B=3.45, 95% CI 0.23 to 6.77, p=0.04) over time, but in a multivariable model these associations disappeared (B=1.22, 95% CI -3.81 to 6.26, p=0.64; and B=2.94, 95% CI -0.63 to 6.61, p=0.11, respectively). Prevalent IBD was not associated with clinical outcomes over time. Incident AAU also was not associated with the clinical outcomes over time. Incident IBD showed a trend towards worse function (BASFI) over time in a univariable model (B=1.84, 95% CI -0.10 to 3.78, p=0.06), and also in a multivariable model (B=1.40, 95% CI 0.05 to 3.60, p=0.06).
Conclusions The presence of AAU and IBD at baseline was not associated with a worse course of QoL or radiographic damage over time. However, patients with new-onset IBD tended to have more functional disability over time in comparison with patients who do not develop IBD.
Disclosure of Interest None declared