Effect of body mass index on outcome in pediatric heart transplant patients

Obesity and cachexia are risk factors for adverse outcomes in adult transplant patients. However, little is known about the effects of body mass index (BMI) on outcomes in pediatric heart transplant patients.

Patients > 2 years of age undergoing heart transplantation from 1985 to 2004 at our institution were included in this study. BMI was assessed at the time of transplant and at 1 year post-transplant. Long-term outcomes were assessed by weight group.

The cohort included 105 patients with a mean age at transplant of 9.6 +/- 5.3 years. The mean BMI percentile at the time of transplant was 39 +/- 34, with 22 (21%) patients underweight (< 5th percentile) and 8 (8%) patients overweight (> or = 95th percentile). Among patients surviving to 1 year (n = 92), the mean BMI percentile increased to 57 +/- 33 (p < 0.05). Overall graft survival was decreased in patients underweight at transplant, mean 6.7 years (95% confidence interval [CI] 3.6 to 9.9), vs normal weight patients, mean 10.6 years (95% CI 8.8 to 12.4) (p < 0.05). Patients overweight at transplant did not have decreased graft survival. Neither low nor high BMI at 1 year post-transplant was associated with adverse outcomes. On multivariate analysis, being underweight at transplant was an independent predictor of decreased graft survival (p = 0.03).

Weight gain was nearly universal post-transplant with only 4% of patients underweight at 1 year. In the small number of patients overweight at transplant, graft survival was similar to normal-weight patients. Conversely, being underweight at transplant was an independent predictor of decreased graft survival.