Impact of Annual Dry Weight Changes on Mortality and Cardiovascular Outcomes in Patients Undergoing Haemodialysis.

backgroundWhile obesity confers a survival advantage, weight loss adversely affects the survival of patients undergoing haemodialysis. However, given the limited information regarding its long-term effects on mortality and cardiovascular events, the health benefits of weight gain remain uncertain, particularly in Asian patients undergoing haemodialysis.

methodsIn a prospective multicentre cohort of patients undergoing haemodialysis in South Korea, patients whose dry weight was recorded at baseline and after 1 year were analysed. Patients were stratified into five groups according to annual dry weight change: stable (-2.0% to 1.9%, n = 245), mild (2.0% to 6.9%, n = 92) and moderate (≥ 7.0%, n = 20) dry weight gain and mild (-5.0% to -2.1%, n = 91) and moderate (< -5.0%, n = 77) dry weight loss. The associations of annual dry weight change with physical function and health-related quality of life were examined using cross-sectional analysis. The impact of annual dry weight changes on all-cause mortality and a composite of major adverse cardiovascular events (MACEs), defined as myocardial infarction, unstable angina, ischaemic stroke and peripheral artery disease requiring revascularization, was assessed in a longitudinal cohort of 525 individuals.

resultsIn cross-sectional analysis, patients with diminished physical ability had a higher frequency of dry weight fluctuations. In longitudinal analysis, the mean age of the study participants was 59.9 years, and 62.3% were men. During a median follow-up of 3.1 years, death and MACE occurred in 105 (20.0%) and 31 (5.9%) patients, respectively. The risk of all-cause mortality was higher in patients with moderate dry weight gain or loss than in those with stable dry weight (adjusted hazard ratio [aHR] for moderate weight gain, 2.22; 95% confidence interval [CI], 0.96-5.13; p = 0.06; and aHR for moderate weight loss, 1.78; 95% CI, 1.07-2.95; p = 0.03). The risk of MACE was significantly higher in patients with weight gain (including mild and moderate) than in those with a stable dry weight (aHR, 3.02; 95% CI, 1.32-6.88; p = 0.009). Specifically, the increased risk of all-cause mortality attributable to moderate dry weight gain was limited to patients with obesity, whereas that for moderate dry weight loss was limited to patients with a normal body mass index.

conclusionModerate weight gain and loss were differentially associated with lower survival among patients undergoing haemodialysis, with the former in patients with obesity and the latter in normal-weight patients. Particularly, dry weight gain increased the risk of cardiovascular events.