OBJECTIVE: To estimate 22-year trends in scleritis prevalence and incidence and associations with infectious/immune-mediated inflammatory diseases (I-IMIDs) in the United Kingdom (UK).
METHODS: Retrospective cross-sectional and population cohort study (1997-2018) included 10,939,823 patients (n=2946 incident scleritis cases) in The Health Improvement Network (THIN), a nationally-representative primary care records database. Case-control and cohort study (1995-2019) included 3005 incident scleritis cases and 12,020 control patients matched by age, sex, region and Townsend Deprivation Index (TDI). We adjusted Poisson, Logistic and Cox proportional hazard multivariable models by age, sex, TDI, race/ethnicity, smoking, nation and body mass index category. Estimates include 95% confidence intervals.
RESULTS: Scleritis incidence rates declined from 4·23(2·16-6·31) to 2·79(2·19-3·39) per 100,000 person-years between 1997 and 2018. Prevalence was 93·62(90·17-97·07)/100,000 people in 2018 (61,650 UK patients). Amongst 2946 incident scleritis patients, 62·2%(n=1831) were female, mean age was 44·9(SD17·6, range 1-93) years and 88·8%(n=1257) were White. Higher risk of incident scleritis was associated with female sex (adjusted incidence rate ratio [aIRR]=1·54, 1·43-1·66,p<0.001), Black (aIRR=1·52, 1·14-2·01,p=0.004) or South Asian race/ethnicity (aIRR=1·50, 1·19-1·90,p<0.001) versus White, and older age (peak aIRR=4·95, 3·99-6·14,p<0.001 for ages 51-60 years versus ≤10 years). Compared to controls, scleritis patients had 2-fold increased risk of prior I-IMID diagnosis (p<0.001, 17 I-IMIDs) and significantly increased risk of subsequent diagnosis of 13 I-IMIDs. Strongest associations included granulomatosis with polyangiitis, Behçet's disease, and Sjögren's syndrome.
CONCLUSION: Over 1997-2018 the UK incidence of scleritis declined from 4·23 to 2·79/100,000 persons/year. Incident scleritis was associated with 19 I-IMIDs, providing data for rational investigation and cross-specialty engagement.
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© 2021 The Authors. Arthritis & Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology.