Association between atopic keratoconjunctivitis and the risk of corneal ulcer

AimsTo investigate the risk of corneal ulcer in patients with atopic keratoconjunctivitis (AKC).MethodsThe nationwide, population-based, retrospective, matched cohort study included 171 019 newly diagnosed patients with AKC who were identified by the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM), code 372.05, and selected from the Taiwan National Health Insurance Research Database. The age-, sex- and potential comorbidities-matched control group included 171 019 patients with non-AKC selected from the Taiwan Longitudinal Health Insurance Database 2000. Patient information was collected between 1 January 2004 and 31 December 2011, and both groups of patients were tracked from the index date until December 2013. The incidence and risk of corneal ulcer (ICD-9-CM code 370.0 except for 370.07) was compared between the groups. A Cox proportional hazard regression analysis was performed to obtain the adjusted HR for corneal ulcer. The cumulative corneal ulcer incidence rate was calculated with the Kaplan-Meier analysis.ResultsIn total, 2018 patients with AKC and 1481 controls developed a corneal ulcer during the follow-up period. The incidence rate of corneal ulcer was 1.42 times (95% CI1.33 to 1.52; p