Supplementary Material for: Association between Chronic Kidney Disease and Risk of Cataract: A Nationwide Retrospective Cohort Study
Background: Previous studies have established a relationship between chronic kidney disease (CKD) and cataract, but the relationship between the severity of renal impairment and risk of cataract is uncertain. This study investigates the relationship between the severity of renal disease and cataract in a nationwide sample from Taiwan. Methods: The cohort from 1-million National Health Insurance beneficiaries from Taiwan was retrospectively analyzed. All adult beneficiaries were followed from January 1, 2005 until December 31, 2013, to identify patients who underwent cataract surgeries. On the basis of the ambulatory care records, those diagnosed with CKD (ICD-9-CM code: 585) during the follow-up period were enrolled as CKD patients after careful evaluation. Each patient with CKD was age- and gender-matched with 4 individuals who did not have CKD. Cox regression models were applied to compare the hazard of cataract surgery in individuals with and without CKD. Subgroup analysis was used to compare patients with end-stage renal disease (ESRD) with age- and gender-matched non-CKD individuals. ESRD was defined by CKD patients who need regular renal replacement therapy. The same method was applied to evaluate hazard ratios (HRs). Results: After age and gender matching, there were 11,881 patients in the CKD group and 47,524 in the non-CKD group. After control for possible confounding, the adjusted HR (aHR) of cataract was 1.84 (95% CI 1.73-1.95) for the CKD group. Subgroup analysis of patients with ESRD (n = 3,209) and non-CKD individuals (n = 12,836), with matching done on the basis of age and gender, indicated an aHR of cataract was 2.33 (95% CI 2.10-2.59) for the ESRD group. Conclusions: This study indicates a relationship between CKD and cataract, and suggests that the risk for cataract increases with the severity of renal impairment.