The effect of body mass index on survival following heart transplantation: Do outcomes support consensus guidelines?

OBJECTIVE: To determine the relationship between body mass index (BMI) at the time of transplant and posttransplant survival and morbidity. SUMMARY BACKGROUND DATA: The recent International Society for Heart and Lung Transplantation listing criteria for heart transplantation stated that candidates should achieve a BMI <30 kg/m-or percent ideal body weight <140%-before listing for cardiac transplantation. However, data to support these recommendations are limited and often conflicting. METHODS: United Network of Organ Sharing provided de-identified patient-level data. Analysis included 19,593 orthotopic heart transplant recipients aged ≥18 years and transplanted January 1 1995-December 31 2005. Follow-up data were provided through February 8, 2008. Recipients were stratified by BMI at the time of transplantation: BMI <18.5 (underweight), 18.5 to 24.99 (normal weight), 25 to 29.99 (overweight), 30 to 34.99 (obesity class I), and ≥35 (obesity class II/III). The primary outcome measure was post-transplant survival. RESULTS: Risk-adjusted median survival in the underweight, normal weight, overweight, obesity I, and obesity II/III groups was 8.31, 10.20, 10.03, 9.51, and 9.05 years, respectively. In multivariate Cox proportional hazards regression, BMI in the overweight (HR = 1.08, 0.99-1.17; P = 0.055) and obesity I (HR = 1.05, 0.99-1.12; P = 0.091) ranges were not associated with significantly diminished survival. However, BMI in the underweight (HR = 1.26, 1.11-1.43; P < 0.001) and obesity II/III (HR = 1.18, 1.01-1.38; P = 0.030) ranges were associated with diminished posttransplant survival. CONCLUSION: Findings from this analysis do not suggest that obesity I (BMI of 30-34.99) is associated with significantly higher morbidity and mortality. However, underweight and obesity II/III recipients have significantly higher morbidity and mortality compared with other groups.