Background Little is known about the characteristics of patients with ankylosing spondylitis (AS) who develop extra-articular manifestations (EAM), such as acute anterior uveitis (AAU), inflammatory bowel disease (IBD), and psoriasis.
Objectives To identify characteristics associated with the development of EAMs in a prevalence cohort of patients with AS.
Methods 12-Year follow-up data from patients included in the Outcome in AS International Study (OASIS) were used. Additionally, two independent extractors checked medical charts for the presence of AAU, IBD or psoriasis. At baseline, logistic regression was performed to identify demographic, clinical, and radiographic characteristics associated with the presence of any EAM. Cox regression and survival analyses were performed to identify characteristics associated with development of any EAM over time, using both characteristics at baseline and at the time of diagnosis of an EAM.
Results 216 patients were included (mean age 43.6 years (SD 12.7), 154 (71%) men, mean symptom duration 20.5 years (SD 11.7), 174 (85%) HLA-B27 positive and mean follow-up 8.3 years (SD 4.3)). At baseline, 59 (27%) patients had any EAM, of which 39 (18%) AAU, 15 (7%) IBD, and 9 (4%) psoriasis. Four patients (2%) had more than one EAM. At baseline, patients with AAU compared with patients without AAU were older (49.1 vs 42.4 years, p<0.01), had a longer symptom duration (25.9 vs 19.3 years, p<0.01), and more radiographic damage (modified Stoke AS Spinal Score 16.9 vs 10.6, p=0.03). Patients with psoriasis compared with patients without psoriasis were older (51.3 vs 43.3 years, p=0.05). There were no differences between patients with and without IBD. During follow-up 27 patients developed a new EAM; 19 AAU, 9 IBD, and 5 psoriasis with incidence rates of 0.9%, 0.4%, and 0.02% per year, respectively. The following characteristics at the time of diagnosis of the EAM were associated with the development of IBD in univariable analysis: ASDAS (Hazard Ratio [HR] 2.81, 95% Confidence Interval [95% CI] 1.43-5.53), BASDAI (HR 1.47 95% CI 1.09-1.98), CRP (HR 1.02, 95% CI 1.00-1.05), BASFI (HR 1.40, 95% CI 1.09-1.80) and BAS-G (HR 1.46, 95% CI 1.10-1.96). Moreover, CRP was weakly associated with the development of AAU (HR 1.02, 95% CI 1.01-1.04). No significant associations with development of psoriasis were found.
Conclusions At baseline, a substantial number of patients already had an EAM in this prevalence cohort with relatively long symptom duration. Development of new EAMs was infrequently observed. In particular disease activity, but also physical function and patient global assessment, were associated with development of IBD. CRP was associated with the development of AAU.
Disclosure of Interest None declared