Weight loss prior to lung transplantation is associated with improved survival

Abstract

Background: Obesity is associated with increased mortality after lung transplantation and is a relative contraindication to transplant. It is unknown whether weight reduction prior to transplantation ameliorates this risk. Our objective was to determine whether weight loss prior to lung transplantation improves survival.

Methods: Our investigation was a two-center, retrospective cohort study of lung transplant recipients between January 1, 2000 and November 5, 2010. Change in weight, demographics, transplant details, lung allocation score, length of intensive care and mechanical ventilator days and graft and patient survival were abstracted. Wilcoxon's signed-rank test and the Cox proportional hazard model were used for analysis where appropriate.

Results: Three hundred fifty-five patients (55% male, median age 59 years) satisfied inclusion and exclusion criteria. After adjusting for standard demographic and clinical measures, a 1-unit reduction in BMI pre-transplant was associated with a reduced risk of death with a hazard ratio 0.89 (95% confidence interval 0.82 to 0.96; p = 0.004). This survival benefit persisted in the group with baseline BMI ≥ 25 kg/m(2) (overweight and obese) and hazard ratio 0.85 (95% CI 0.77 to 0.95; p = 0.003), but not in those with a BMI ≤ 24.9 kg/m(2). The 1-unit reduction in BMI was also associated with a 6.1% decrease in median mechanical ventilator days (p = 0.02) and a trend toward decreased intensive care unit length of stay (p = 0.06).

Conclusions: A reduction in BMI prior to lung transplantation was associated with a reduction in the risk of death and mechanical ventilator days. A greater reduction in BMI was associated with a greater survival benefit.

Keywords: lung transplantation; obesity; patient selection; survival; weight loss.

Figure 1

Kaplan-Meier curve demonstrating survival separated by Body Mass Index (BMI) in kg/m². Underweight is BMI <18.5 kg/m², normal weight is a BMI 18.5 kg/m² - 24.9 kg/m², overweight is BMI 25-29.9 kg/m², obese is BMI >30 kg/m².