Purpose
Population-based studies of scleritis and episcleritis are lacking. We aimed to ascertain the incidence of scleritis and episcleritis in a Hawaiian population, describe variations by age, gender, and race, and compare clinical characteristics of both conditions.
Methods
All electronic medical records for enrollees in Kaiser Permanente Hawaii (n =217,061) from 1/1/2006 to 12/31/2007 were searched for International Classification of Diseases, 9th Edition (ICD9) 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-, gender-, and race-specific rates, assuming a Poisson distribution. Data on clinical characteristics were compared between scleritis and episcleritis cases using Fisher’s exact test.
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 3.9 and 21.4 cases per 100,000 person-years, respectively, (95% CI: 2.3-6.3, 17.3-26.3). Women were found to have higher incidence rates of scleritis and episcleritis (p=0.04, p=0.06). Pacific Islanders were the most underrepresented racial group among cases of scleritis and episcleritis (p=0.005, p≤0.001). Blacks had the highest incidence of scleritis (p≤0.001). Compared to all others, Asians had a higher incidence of scleritis and episcleritis (p≤0.001, p≤0.001), as did Caucasians (p=0.08, p≤0.001). A comparison of clinical characteristics of scleritis and episcleritis was notable for a higher proportion of patients with rheumatoid arthritis in those with scleritis (p≤0.001); a higher rate of ocular complications in scleritis (p=0.02); and more frequent prescriptions of mydriatic eye drops, systemic immunosuppressants, including systemic steroids, and topical steroids (p=0.02, 0.005, 0.03, 0.05, respectively) to scleritis patients.
Conclusions
These results provide a population-based estimate of the incidence of scleritis and episcleritis in a diverse population and highlight differences in demographic and clinical characteristics.
Keywords: 463 clinical (human) or epidemiologic studies: prevalence/incidence •
708 sclera •
557 inflammation