Underweight and obesity increase the risk of mortality after lung transplantation: a systematic review and meta-analysis.

Many studies have found an association between abnormal body mass index (BMI) and poor outcomes among lung transplant recipients. We performed a systematic review and meta-analysis to identify outcomes associated with an abnormal pretransplant BMI after lung transplantation (LTx). The MEDLINE and EMBASE databases were searched from inception to May 2015 with focus on original observational studies with post-transplant survival data in candidates with abnormal BMI (underweight, overweight, or obese). We performed meta-analyses examining survival and primary graft dysfunction after LTx. We identified 866 citations; 13 observational cohort studies involving 40 742 participants met our inclusion criteria for systematic review. Seven of the 13 were included in the meta-analysis. There was a significant risk of mortality after LTx in candidates with underweight and obesity (underweight versus normal, relative risk [RR] 1.36, 95% confidence interval [CI] 1.11-1.66, I(2)  = 0%; obesity vs. normal, RR 1.90, 95% CI 1.45-2.56, I(2)  = 0%; overweight vs. normal, RR 1.36, 95% CI 1.11-1.66, I(2)  = 0). There was also a significant risk of primary graft dysfunction in obese (RR 1.92, 95% CI 1.39-2.65, I(2)  = 0%) and overweight (RR 1.72, 95% CI, 1.32-2.24, I(2)  = 0%) candidates. Lung transplant candidates who are underweight or obese have a higher risk of post-transplant mortality than recipients with a normal BMI.