Association between atopic keratoconjunctivitis and the risk of keratoconus

Abstract

Purpose: To investigate the risk of keratoconus (KCN) in patients with atopic keratoconjunctivitis (AKC).

Methods: This nationwide, retrospective, matched cohort study included 186 202 newly diagnosed AKC patients 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- and sex-matched control group included 186 202 non-AKC patients 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 KCN (ICD-9-CM, code 371.6) were compared between the groups. A Cox proportional hazard regression analysis was performed to obtain the adjusted hazard ratio (HR) for KCN. The cumulative KCN incidence rate was calculated with the Kaplan-Meier analysis.

Results: In total, 62 AKC patients and 26 controls developed KCN during the follow-up period. The incidence rate of KCN was 2.49 times (95% confidence interval [CI] = 1.57-3.93; p < 0.0001) higher in AKC patients than in controls. After adjusting for potential confounders, AKC patients were 2.25 times more likely to develop KCN than controls (adjusted HR, 2.25; 95% CI = 1.41-3.58; p < 0.05).

Conclusion: Atopic keratoconjunctivitis (AKC) patients had an increased risk of developing KCN. Therefore, AKC patients should be advised of this risk.

Keywords: Taiwan Longitudinal Health Insurance Database; atopic keratoconjunctivitis; cohort study; keratoconus.