Body Composition and Mortality after Adult Lung Transplantation in the United States

Abstract

Rationale: Obesity and underweight are contraindications to lung transplantation based on their associations with mortality in studies performed before implementation of the lung allocation score (LAS)-based organ allocation system in the United States Objectives: To determine the associations of body mass index (BMI) and plasma leptin levels with survival after lung transplantation.Methods: We used multivariable-adjusted regression models to examine associations between BMI and 1-year mortality in 9,073 adults who underwent lung transplantation in the United States between May 2005 and June 2011, and plasma leptin and mortality in 599 Lung Transplant Outcomes Group study participants. We measured body fat and skeletal muscle mass using whole-body dual X-ray absorptiometry in 142 adult lung transplant candidates.Measurements and Main Results: Adjusted mortality rates were similar among normal weight (BMI 18.5-24.9 kg/m 2 ), overweight , and class I obese (BMI 30-34.9) transplant recipients. Underweight (BMI , 18.5) was associated with a 35% increased rate of death (95% confidence interval, 10-66%). Class II-III obesity (BMI > 35 kg/m 2 ) was associated with a nearly twofold increase in mortality (hazard ratio, 1.9; 95% confidence interval, 1.3-2.8). Higher leptin levels were associated with increased mortality after transplant surgery performed without cardiopulmonary bypass (P for interaction = 0.03). A BMI greater than or equal to 30 kg/m 2 was 26% sensitive and 97% specific for total body fat-defined obesity.Conclusions: A BMI of 30.0-34.9 kg/m 2 is not associated with 1-year mortality after lung transplantation in the LAS era, perhaps because of its low sensitivity for obesity. The association between leptin and mortality suggests the need to validate alternative methods to measure obesity in candidates for lung transplantation. A BMI greater than or equal to 30 kg/m 2 may no longer contraindicate lung transplantation.

Frailty Phenotypes, Disability, and Outcomes in Adult Candidates for Lung Transplantation

“…We previously demonstrated that preoperative underweight status and hypoalbuminemia are strongly associated with mortality after lung transplant (34,56). Also, low lean muscle mass sarcopenia is common in patients with COPD and in lung transplant candidates (34,47). Consistent with these reports, lean muscle mass correlated with both of the frailty measures used in this study.…”

“…For example, low BMI and hypoalbuminemia are associated with both frailty and sarcopenia (presumably because abnormally low lean muscle mass and function is a putative driver of the frail phenotype) (29,40,42,54,55). We previously demonstrated that preoperative underweight status and hypoalbuminemia are strongly associated with mortality after lung transplant (34,56). Also, low lean muscle mass sarcopenia is common in patients with COPD and in lung transplant candidates (34,47).…”

Severe underweight decreases the survival rate in adult lung transplantation

“…The previous studies have identified an association between obesity and an increased risk of PGF [18,19]. Singer et al suggested that adiposity is associated with inflammatory adipokines and other cytokines, which can cause PGF [20]. Several cytokines and chemokines have been found to be associated with PGF [21,22].…”

Sarcopenia of thoracic muscle mass is not a risk factor for survival in lung transplant recipients

“…Therefore, obesity was associated with an increased mortality rate after LTx. However, another study suggested that obesity is not associated with 1-year mortality after LTx, and a BMI greater than 30 kg/m 2 may no longer represent a contraindication (28). Overall, controversy surrounds interpretation the relationship between obesity and survival rates in LTx patients.…”