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

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

Retrospective, population-based cohort study.

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.

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).

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.