Survival Benefit of Maintained or Increased Body Mass Index in Patients Undergoing Extended-Hours Hemodialysis Without Dietary Restrictions.

OBJECTIVE: Low body mass index (BMI) is a potential risk factor for mortality in patients on maintenance hemodialysis. This suggests the usefulness of BMI as a prognostic factor and implies the importance of nutritional status, inflammation, and oxidative stress, all of which affect BMI. We aimed to evaluate BMI changes over time and the mortality risk in patients undergoing a novel combination therapy consisting of an extended-hours hemodialysis protocol without dietary restrictions, which enabled sufficient nutrition. DESIGN AND METHODS: This is a retrospective cohort study. Patients were divided into 2 groups based on BMI change (ΔBMI < 0, ΔBMI ≥ 0) between the 3rd and 12th month after transfer to the clinic. We studied the associations of BMI changes with all-cause mortality. Further subgroup analyses were performed using Cox models. We finally studied 187 patients who were receiving the combined therapy. The main outcome measure was all-cause mortality of the study group. RESULTS: The median (interquartile range) follow-up time was 4.9 (3.0-8.6) years. Overall, 138 patients were in the ΔBMI ≥ 0 group. As per unadjusted and adjusted Cox models, maintained or increased BMI during this period was associated with hazard ratios of 0.45 (confidence interval 0.23-0.87, P < .05) and 0.35 (confidence interval 0.17-0.75, P < .01) for all-cause mortality, respectively. In the same group, maintained or increased BMI was found to be significantly associated with decreased mortality in female, older, and nondiabetic patients. The data indicated that diabetic status could have a modifying effect on the association between variation in BMI and mortality (P = .006). CONCLUSIONS: Extended-hours hemodialysis without dietary restrictions led to a beneficial effect of maintenance or increase in BMI, especially in females, patients aged ≥65 years, and those without diabetic nephropathy, which could lead to prolonged survival.