The impact of recipient body mass index on survival after lung transplantation

Abstract

Background: Lung transplant (LTx) candidates are frequently over or underweight. Few studies have examined recipient weight and outcomes after LTx. The United Network for Organ Sharing (UNOS) database provides an opportunity to examine outcomes related to body mass index (BMI) in a large cohort of LTx patients.

Methods: The UNOS data set was retrospectively reviewed for 11,411 adult primary LTx patients (1998 to 2008). Patients were stratified by recipient BMI (kg/m(2)): less than 18.5 (underweight), 18.5 to 24.9 (normal), 25.0 to 29.9 (overweight), more than 30 (obese). All-cause mortality was examined with Cox proportional hazard regression incorporating 15 variables. Survival was modeled using the Kaplan-Meier method.

Results: Of 11,411 recipients, 1,355 (11.9%) were underweight, 4,998 (43.8%) were normal weight, 3,662 (62.1%) were overweight, and 1,396 (12.2%) were obese. During the study, 4,959 patients (43.5%) died. Mortality was significantly different between the strata, with incremental increases in death for each BMI category above or below normal. On multivariable analysis, BMI strata predicted death compared with normal weight. Risk of death was increased in recipients who were underweight (hazard ratio [HR], 1.14; 95% confidence interval [CI], 1.03-1.26; p = 0.01), overweight (HR, 1.06; 95% CI, 0.99-1.14; p = 0.1), and obese (HR, 1.16; 95% CI, 1.04-1.28; p = 0.005). Kaplan-Meier modeling showed a significant effect of BMI on survival; however, this effect was no longer significant when first-year deaths were excluded.

Conclusions: Mortality is higher in underweight, overweight, and obese LTx patients than in normal-weight controls. However, this effect appears to be governed by survival in the first year after LTx.