Comparison of cystatin C- and creatinine-based estimated glomerular filtration rates for predicting all-cause mortality in Japanese patients with type 2 diabetes: the Fukuoka Diabetes Registry

Background There is little information about the predictive ability of cystatin C-based estimated glomerular filtration rates (eGFR Cys ) for all-cause mortality in Asian populations. We compared the discriminatory ability of eGFR Cys for all-cause mortality with that of creatinine-based estimated glomerular filtration rates (eGFR Cr ) in Japanese patients with type 2 diabetes. Methods A total of 4869 participants were classified into four categories (eGFR ≤29, 30–59, 60–89, and ≥90 ml/min/1.73 m 2 ) by eGFR Cr and eGFR Cys , and followed up for a median of 3.3 years. Results 150 deaths were identified. The multivariable-adjusted risk of all-cause mortality was significantly increased in eGFR Cr ≤29 ml/min/1.73 m 2 compared with eGFR Cr ≥90 ml/min/1.73 m 2 [hazard ratio (HR) 2.4 (95 % confidence interval (95 % CI) 1.2–5.0)], whereas it was significantly increased in eGFR Cys 59 ml/min/1.73 m 2 or lower [30–59 ml/min/1.73 m 2 , HR 1.9 (95 % CI 1.1–3.5); ≤29 ml/min/1.73 m 2 , HR 5.8 (95 % CI 2.8–12.0)]. Comparing eGFR Cys with eGFR Cr , the proportions of participants reclassified to lower and higher eGFR stages were 6.3 and 28.8 %, respectively. The multivariable-adjusted HRs for all-cause mortality were 1.8 (95 % CI 1.1–2.9) and 0.7 (95 % CI 0.4–1.1), respectively. The C statistic of the model including eGFR Cys and other risk factors was significantly increased compared with the model including eGFR Cr . The net reclassification improvement and the integrated discrimination improvement were significantly positive. Conclusions Our findings suggest that eGFR Cys has a stronger association with all-cause mortality and is superior to eGFR Cr for predicting all-cause mortality in Japanese patients with type 2 diabetes.