Cataract surgery in a population-based cohort of patients with type 1 diabetes: long-term incidence and risk factors

Purpose: To estimate the long-term cumulative incidence of cataract surgery and associated risk factors in a 25-year follow-up of a population-based cohort of patients with type 1 diabetes. Methods: Based on insulin prescriptions, a population-based cohort of 727 patients with type 1 diabetes was identified in 1973. In 1981-1982 diabetic retinopathy was graded and other markers of diabetes were measured in 573 patients who participated in a clinical baseline examination. Based on data from the Danish National Patient Registry, patients were followed until November 2006 and cataract surgery was evaluated during follow-up. Results: The 25-year crude cumulative incidence of cataract surgery was 20.8% (117 of 562 patients at risk), corresponding to a mortality-adjusted incidence of 29.4% [95% confidence interval (CI) 25.6-33.1%]. Median age and duration of diabetes at the time of surgery were 59.3 and 42 years, respectively. Cataract surgery in the cohort took place approximately 20 years earlier compared to non-diabetic persons. In a multivariate regression analysis, baseline age [hazard ratio (HR) 1.89 per 10 years, 95% CI 1.46-2.27] and maculopathy (HR 1.89, 95% CI 1.05-3.40) were the only statistically significant predictors of cataract surgery. Duration of diabetes, gender, glycaemic regulation, proteinuria, smoking, blood pressure and level of retinopathy were not associated with cataract surgery. Conclusion: Type 1 diabetes is associated with a high long-term incidence of cataract surgery. The association between maculopathy and subsequent cataract surgery is a novel finding and should be addressed in future studies.