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

Abstract

A body mass index (BMI) below morbid obesity range is often a requirement for kidney transplant waitlisting, 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. Timedependent 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/m 2 . Each kg/m 2 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. Transplantwaitlisted 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.

Changes in Body Weight and Subsequent Mortality

“…Although weight gain was not significantly beneficial in patients with baseline obesity (BMI .30 kg/m 2 ), it was also not detrimental. This study reaffirms in a prospective and well controlled multiethnic cohort the findings from previous observational studies about the detrimental nature of unintentional loss of weight or various determinants of body mass (including muscle or fat mass), and about the lack of adverse effects and potential benefit of unintentional gain of the same parameters (5,11,12,(15)(16)(17). The reason behind the more subdued benefit associated with weight gain in patients with baseline obesity in the study by Cabezas-Rodriguez et al is not immediately apparent; however, it could be speculated that perhaps weight gain in obese and lean patients may happen for different reasons and it may have different effects on body composition.…”

Association of Pretransplant Serum Phosphorus with Posttransplant Outcomes

“…The median cohort time was 803 days (interquartile range was 384 to 1330 days). The basic characteristics of waitlisted, but nontransplanted, patients have been described elsewhere (34). Tables 1 and 2 show the clinical, demographic, and laboratory data of the 9384 transplanted patients across five pretransplant serum phosphorus categories.…”

Pre-ESRD Changes in Body Weight and Survival in Nursing Home Residents Starting Dialysis

“…Subsequent studies examined the association between changes in BMI or muscle mass after starting dialysis and mortality. In these studies, changes in serum creatinine concentration (a presumed marker for changes in muscle mass) were more predictive of mortality than weight loss alone (15,16). In fact, the mortality risk associated with weight loss was offset by gaining muscle mass, whereas the benefit of weight gain was diminished by losing muscle mass.…”