Study population

SEED is a population-based cohort study of Chinese, Malay and Indian adults (n = 10,033) aged 40–80 years at baseline aimed to investigate the prevalence, incidence and risk factors of age-related eye diseases, and also the burden of major systemic diseases such as diabetes, hypertension and CKD. SEED included three independent population-based studies, the Singapore Malay Eye Study (SiMES, 2004–2006), the Singapore Indian Eye Study (SINDI, 2007–2009) and the Singapore Chinese Eye Study (SCES, 2009–2011) [13, 14]. Detailed methodology for these studies was previously reported [15]. Subjects were recruited in the same geographical area using age-stratified random sampling from computer-generated random lists of individuals 40 to 80 years of age residing in Singapore. All 3 studies followed similar protocols and were conducted in the same center (Singapore Eye Research Institute). The current study included 1970 persons who had CKD at baseline and outcome ESRD was obtained by linkage to the national renal registry. Previous investigators evaluating ESRF risk prediction used the Modification of Diet in Renal Diseases (MDRD) formula to estimate GFR [6, 9]. However, this formula tends to under-estimate GFR, possibly misclassifying patients with normal kidney function as mild CKD, while the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula may be more accurate among those with normal or slightly lower GFR and correlated well with adverse outcomes internationally and among Asians [16–18]. Since our cohort was derived from population-based studies and thus more likely to include individuals with better renal function than cohorts selected from nephrology or hospital-based clinics, we considered the CKD-EPI equation to be more suitable to calculate eGFR for subjects in this study. CKD was defined according to modified Kidney Disease: Improving Global Outcomes (KDIGO) 2012 clinical practice guideline as eGFR <60 ml/min/1.73m² or albuminuria (urinary albumin-to-creatinine ratio, UACR) >30 mg/g [19, 20]. Among 2524 individuals with eGFR <60 ml/min/1.73m² or UACR >30 mg/g, we excluded those with Stage 5 CKD (eGFR <15 ml/min/1.73 m², n = 22) or had missing data on serum creatinine (n = 22) or urinary albumin-to-creatinine ratio (n = 510). Thus, 1970 individuals were included in the development cohort.