Introduction: This study aimed to determine the association between extra-articular manifestations (EAMs) and baseline characteristics of patients with ankylosing spondylitis (AS) and identify their potential risk factors in an observational cohort.
Methods: We analyzed the data of consecutive patients with AS obtained between April 2016 and May 2019 from the ongoing Chinese Ankylosing Spondylitis Prospective Imaging Cohort.
Results: Among the 1414 patients with AS, 23.1% had experienced EAMs at baseline. The prevalence rates of acute anterior uveitis (AAU), inflammatory bowel disease, and psoriasis among patients with AS were 16.7, 6.9, and 2.6%, respectively, and the prevalence of AAU increased significantly with the disease duration. Patients with comorbidity of AAU and psoriasis had Ankylosing Spondylitis Disease Activity Score (ASDAS) than patients without EAMs (2.16 ± 0.984 vs. 1.99 ± 0.956 [p = 0.025] and 2.36 ± 1.01 vs. 1.99 ± 0.96 [p = 0.025]). Among the 1087 patients with AS without EAMs at baseline, 98 developed EAMs during follow-up. Long disease duration (> 10 years) and high disease activity at baseline (ASDAS > 2.1) were associated with the risk of new-onset EAMs (hazard ratio [HR] [95% confidence interval, CI], 2.150 [1.229-3.762] and 2.896 [1.509-5.561], respectively) and new-onset AAU (HR [95% CI], 2.197 [1.325-3.642] and 3.717 [1.611-8.574], respectively).
Conclusions: In Chinese patients with AS, patients with comorbidity of AAU and psoriasis had higher disease activity scores than patients without EAMs. Furthermore, the risk of AAU or combined EAMs increases with the duration of AS and appears to be associated with higher cumulative exposure to inflammation.
Keywords: Acute anterior uveitis; Ankylosing spondylitis; Inflammatory bowel disease; Psoriasis.