Incidence of scleritis and episcleritis: results from the Pacific Ocular Inflammation Study.

Purpose: To ascertain the incidence of scleritis and episcleritis in a Hawaiian population and describe variations by age, sex, and race.

Design: Retrospective, population-based cohort study.

Methods: All electronic medical records for enrollees in Kaiser Permanente Hawaii (n = 217,061) from January 1, 2006 to December 31, 2007 were searched for International Classification of Diseases, 9th Edition (ICD-9) codes associated with ocular inflammation. Chart review was conducted to verify a clinical diagnosis of scleritis or episcleritis. Confirmed cases were used to calculate incidence rates per 100,000 person-years. Ninety-five percent confidence intervals (CI) were calculated for each incidence rate, including age-, sex-, and race-specific rates, using bias-corrected Poisson regression. To assess for confounding, a multivariate analysis adjusting for age, sex, and race was also performed.

Results: Of 217,061 eligible patients, 17 incident scleritis cases and 93 incident episcleritis cases were confirmed. The overall incidence rates of scleritis and episcleritis were 4.1 (95% CI: 2.6-6.6) and 21.7 (95% CI: 17.7-26.5) cases per 100,000 person-years, respectively. Women were overrepresented among scleritis patients (P = .049). Pacific Islanders were the most underrepresented racial group among cases of scleritis and episcleritis (P = .006, P = .001). Blacks had the highest incidence of scleritis (P = .004).

Conclusions: These results provide a population-based estimate of the incidence of scleritis and episcleritis in a diverse population and highlight differences in patients' demographic characteristics. Differences in incidence by sex and race raise questions about genetic and environmental influences on the development of these conditions.