Association between creatinine to body weight ratio and all-cause mortality: a cohort study of NHANES.

Research on the relationship between the weight-adjusted skeletal muscle mass index and all-cause mortality is rare, and even rarer is the relationship between the creatinine/body weight (Cre/BW) ratio and all-cause mortality. Therefore, this study aimed to investigate the relationship between the Cre/BW ratio and mortality in individuals with normal renal function. This prospective study used data from the National Health and Nutrition Examination Survey (NHANES) database. A Cox hazard model was used to analyze the relationship between the Cre/BW ratio and mortality risk. In total, 45,459 participants were included, of which 49.97% were women, with an average age of 45.68 ± 18.08 years. The incidence of all-cause mortality was 10.9% among these participants during the median (interquartile range) follow-up of 9.6 (5.2, 14.2) years. After adjusting for all covariates, a U-shaped relationship was found between the Cre/BW ratio and all-cause mortality (P for nonlinearity <0.001), with the lowest risk observed at Cre/BW ratios (×100) between 0.821 and 0.987. In the threshold effect analysis, the Cre/BW ratio (×100) had a threshold value of 0.96. When the Cre/BW ratio (×100) was <0.96, all-cause mortality was negatively associated with the Cre/BW ratio (×100) (0.63 (0.41, 0.97)). In contrast, when the Cre/BW ratio (×100) was ≥0.96, the higher Cre/BW ratio was associated with a greater hazard ratio of all-cause mortality (1.67 (1.41, 1.97)). In conclusion, we report a U-shaped relationship between the Cre/BW ratio and all-cause mortality. Controlling the Cre/BW ratio within a certain range may reduce the risk of all-cause mortality.