Among patients receiving maintenance dialysis, weight loss at any body mass index is associated with mortality. However, it is not known whether weight changes before dialysis initiation are associated with mortality and if so, what risks are associated with weight gain or loss.
Linking data from the US Renal Data System to a national registry of nursing home residents, this study identified 11,090 patients who started dialysis between January of 2000 and December of 2006. Patients were categorized according to weight measured between 3 and 6 months before dialysis initiation and the percentage change in body weight before dialysis initiation (divided into quintiles). The outcome was mortality within 1 year of starting dialysis.
There were 361 patients (3.3%) who were underweight (Quételet's [body mass] index<18.5 kg/m(2)) and 4046 patients (36.5%) who were obese (body mass index ≥ 30 kg/m(2)) before dialysis initiation. The median percentage change in body weight before dialysis initiation was -6% (interquartile range=-13% to 1%). There were 6063 deaths (54.7%) over 1 year of follow-up. Compared with patients with minimal weight changes (-3% to 3%, quintile 4), patients with weight loss ≥ 15% (quintile 1) had 35% higher risk for mortality (95% confidence interval, 1.25 to 1.47), whereas those patients with weight gain ≥ 4% (quintile 5) had a 24% higher risk for mortality (95% confidence interval, 1.14 to 1.35) adjusted for baseline body mass index and other confounders.
Among nursing home residents, changes in body weight in advance of dialysis initiation are associated with significantly higher 1-year mortality.