Demographics and medical details including smoking history, comorbidities, cause of CKD, and medication history were collected at enrollment. Comorbidity of CVD was defined as any history of coronary artery disease, peripheral artery disease, cerebrovascular disease, or congestive heart failure. Patients previously diagnosed with diabetes or who were on diet modification or anti-diabetic medication were defined as diabetic patients. The following laboratory variables were measured using an 8-h fasting blood sample at each participating center laboratory: hemoglobin, fasting blood sugar, uric acid, calcium, phosphorous, albumin, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and high sensitivity C-reactive protein (hsCRP). Using a serum separation tube, 10 ml of whole blood was obtained and centrifuged within 1 h for serum separation, then sent to the central laboratory (Lab Genomics, Seoul, Republic of Korea) for measurement of creatinine and intact parathyroid hormone (iPTH). Serum creatinine was measured using an isotope dilution mass spectrometry-traceable method and serum iPTH was measured using chemiluminescence immunoassay. The CKD Epidemiology Collaboration equation based on serum creatinine was used to calculate eGFR17. For urine biochemistry, first-voided urine samples (15 ml) were collected and sent to the central laboratory for urine protein and creatinine assays. Urine protein and creatinine were measured using immunoturbidimetry and isotope dilution mass spectrometry-traceable methods, respectively. Patients were followed every year for renal and cardiovascular events. Death and causes of death were determined using either hospital medical records or the National Health Insurance System (NHIS) and Korea Statistical Information Service.