Associations of pretransplant weight and muscle mass with mortality in renal transplant recipients

Abstract

Background and objectives: The association between pretransplant body composition and posttransplant outcomes in renal transplant recipients is unclear. It was hypothesized that in hemodialysis patients higher muscle mass (represented by higher pretransplant serum creatinine level) and larger body size (represented by higher pretransplant body mass index [BMI]) are associated with better posttransplant outcomes.

Design, setting, participants, & measurements: Linking 5-year patient data of a large dialysis organization (DaVita) to the Scientific Registry of Transplant Recipients, 10,090 hemodialysis patients were identified who underwent kidney transplantation from July 2001 to June 2007. Cox regression hazard ratios and 95% confidence intervals of death and/or graft failure were estimated.

Results: Patients were 49 ± 13 years old and included 49% women, 45% diabetics, and 27% African Americans. In Cox models adjusted for case-mix, nutrition-inflammation complex, and transplant-related covariates, the 3-month-averaged postdialysis weight-based pretransplant BMI of 20 to <22 and < 20 kg/m(2), compared with 22 to <25 kg/m(2), showed a nonsignificant trend toward higher combined posttransplant mortality or graft failure, and even weaker associations existed for BMI ≥ 25 kg/m(2). Compared with pretransplant 3-month- averaged serum creatinine of 8 to <10 mg/dl, there was 2.2-fold higher risk of combined death or graft failure with serum creatinine <4 mg/dl, whereas creatinine ≥14 mg/dl exhibited 22% better graft and patient survival.

Conclusions: Pretransplant obesity does not appear to be associated with poor posttransplant outcomes. Larger pretransplant muscle mass, reflected by higher pretransplant serum creatinine level, is associated with greater posttransplant graft and patient survival.

Figure 1.

HRs (95% confidence intervals) of (A) posttransplant-graft-censored death, (B) death-censored graft failure, and (C) combined mortality and graft failure across the pretransplant BMI categories using Cox regression analyses in 10,090 long-term MHD transplant patients who underwent renal transplantation and were observed over a 6-year observation period (July 2001 to June 2007).

Figure 2.

HRs (and 95% confidence intervals) of (A) posttransplant-graft-censored death, (B) death-censored graft failure, and (C) combined mortality and graft failure across pretransplant serum creatinine categories using Cox regression analyses in 10,090 MHD patients who underwent renal transplantation and were observed over a 6-year observation period (July 2001 to June 2007).

Figure 3.

HRs (and 95% confidence intervals) of graft-censored death across BMI and creatinine categories (subgroup are based on cutoff levels according to the median values of pretransplant BMI and creatinine levels) using Cox regression analyses in 10,090 MHD patients who underwent renal transplantation and were observed over a 6-year observation period (July 2001 to June 2007).