Associations of Body Mass Index and Weight Loss with Mortality in Transplant-Waitlisted Maintenance Hemodialysis Patients

A body mass index (BMI) below morbid obesity range is often a requirement for kidney transplant wait-listing, but data linking BMI changes to mortality during the waitlist period are lacking. By linking the 6-year (7/2001-6/2007) national databases of a large dialysis organization and the Scientific Registry of Transplant Recipients, we identified 14 632 waitlisted hemodialysis patients without kidney transplantation. Time-dependent survival models examined the mortality predictability of 13-week-averaged BMI, pretransplant serum creatinine as a muscle mass surrogate and their changes over time. The patients were on average 52 +/- 13 years old, 40% women and had a BMI of 26.9 +/- 6.3 kg/m2. Each kg/m2 increase of BMI was associated with a death hazard ratio (HR) of 0.96 (95%CI: 0.95-0.97). Compared to the lowest creatinine quintile, the 4th and 5th quintiles had death HRs of 0.75 (0.66-0.86) and 0.57 (0.49-0.66), respectively. Compared to minimal (< +/- 1 kg) weight change over 6 months, those with 3 kg-< 5 kg and >= 5 kg weight loss had death HRs of 1.31 (1.14-1.52) and 1.51 (1.30-1.75), respectively. Similar associations were observed with creatinine changes over time. Transplant-waitlisted hemodialysis patients with lower BMI or muscle mass and/or unintentional weight or muscle loss have higher mortality in this observational study. Impact of intentional weight change remains unclear.