Low BMI and high waist-to-hip ratio are associated with mortality risk among hemodialysis patients: a multicenter prospective cohort study

BACKGROUND: Data are limited on the relationship between waist-to-hip ratio (WHR) and mortality risk among maintenance hemodialysis (MHD) patients. Moreover, the combined association of body mass index (BMI) and WHR with mortality remains uncertain. Therefore, we aimed to explore the individual and combined association of BMI and WHR with the all-cause and cardiovascular disease (CVD) mortality. METHODS: In this multicenter prospective cohort study, we enrolled 1034 MHD patients. The primary outcome was all-cause mortality and secondary outcome was CVD mortality. Multivariable Cox proportional hazards models were used to evaluate the individual and combined association of BMI and WHR with the risk of mortality. RESULTS: A nonlinear inverse relationship was found between BMI and risk of all-cause mortality (P for nonlinearity <.05). Being underweight (<18.5 kg/m(2)) was associated with higher all-cause mortality risk (HR 1.45; 95% CI 1.08–1.94) compared with normal weight (18.5–23.9 kg/m(2)), while being overweight (24–27.9 kg/m(2); HR 0.96; 95% CI 0.70–1.31) and obese (≥28 kg/m(2); HR 1.19; 95% CI 0.62–2.26) showed no significant differences. Of note, WHR was independently and positively associated with all-cause mortality (per standard deviation increase, HR 1.13; 95% CI 1.00–1.27). When analyzed jointly, patients with low BMI (<18.5 kg/m(2)) and high WHR (≥0.95) had the highest risk of all-cause mortality. Similar results were obtained for CVD mortality. CONCLUSIONS: In patients undergoing hemodialysis from China, low BMI and high WHR were individually and jointly associated with higher risk of mortality. Our results emphasize that BMI and WHR may jointly affect the prognosis of MHD patients.