Objectives: Ankylosing spondylitis (AS) is a progressive, systemic, inflammatory autoimmune disease that typically affects young adults. Uveitis is a common extra-articular manifestation of AS. Nevertheless, the magnitude of the risk of AS among patients with uveitis is not clear. The aim of this secondary retrospective cohort study was to investigate the risk of incident AS in patients with uveitis using data from a nationwide, population-based health claims research database.
Method: Using Taiwan's National Health Insurance Research Database, we identified 6637 patients with uveitis between 2000 and 2012. A comparison cohort was assembled, which consisted of five patients without uveitis, based on frequency matching for gender, 10 year age interval, and index year, for each patient with uveitis. Both groups were followed until diagnosis of AS or the end of the follow-up period. A Poisson regression model was used to calculate the incidence rate ratio for AS between the uveitis cohort and the comparison cohort.
Results: Patients with uveitis exhibited a significantly higher incidence of AS than the comparison cohort (adjusted incidence rate ratio = 2.57, p < 0.001). Subgroup analysis with stratification by the interval between the diagnosis of uveitis and AS indicated that the adjusted incidence rates were significantly higher in the uveitis cohort with an interval of up to 7.9 years.
Conclusion: A significant increased risk in AS among patients with uveitis was observed, with a time lag of up to 7.9 years between the diagnosis of uveitis and subsequent diagnosis of AS.