As in the original KFREs, GFR was estimated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2009 creatinine equation.14 (link) Serum creatinine concentrations were standardized to isotope dilution mass spectrometry traceable methods where possible.14 (link) For studies where creatinine measurements were not standardized to isotope dilution mass spectrometry, the creatinine levels were reduced by 5%, as previously reported.15 (link),16 (link) Albuminuria was represented as a log-transformed urine ACR. Alternative measures of urine protein excretion (protein-to-creatinine ratio, 24 hour urine collection, urinary dipstick) were transformed to the ACR using previously developed equations.6 (link),17 (link),18 (link) When available, baseline values for serum albumin, phosphorous, calcium, and bicarbonate, as well as physical examination measures of weight, systolic and diastolic blood pressure were derived from each cohort. Age, sex and ethnicity (black/non-black), as well as the presence of diabetes and hypertension, were also derived from the individual cohorts, with information on race collected as part of routine clinical care for the health systems and as demographic data for the study cohorts. Diabetes was defined as fasting glucose of at least 7.0 mmol/L, non-fasting glucose of at least 11.1 mmol/L or glycated haemoglobin (HbA1c) of at least 6.5%, use of glucose-lowering drugs, or self-reported diabetes. Hypertension was defined as a systolic blood pressure of at least 140 mm Hg, diastolic blood pressure of at least 90 mm Hg, or use of antihypertensive drugs for treatment of hypertension. Potential participants missing any baseline data were excluded from analysis. Information on individual cohorts is provided in eAppendix 1.