NPPB and chronic kidney disease: Multivariate Cox proportional hazards regression analysis demonstrated that serum GDF-15 level was an independent predictor of all-cause mortality after adjusting for age, sex, hemoglobin, log TnT, log BNP, log hsCRP, revascularization, and severe CKD (HR: 1.42; 95% CI: 1.11-1.79; P = 0.0038) (Table 2).