Lung transplantation outcomes in underweight recipients: A single center experience

Background: Current guidelines recommend a body mass index (BMI) of 16 kg/m² as the minimum threshold for lung transplantation, despite mixed evidence on outcomes in underweight patients. The current study aimed to describe survival outcomes of underweight patients who underwent lung transplantation at a single center.

Methods: This retrospective observational study included adult lung transplant recipients who underwent transplantation for the first time between March 2010 and March 2022 at King Faisal Specialist Hospital and Research Center and excluded patients with obesity. We defined an underweight status as a BMI <17 kg/m².

Results: Forty-eight of the 202 lung transplant recipients were underweight at the time of surgery. The underweight patients had similar lengths of hospital (p = 0.53) and intensive care unit (p = 0.81) stays compared to other patients. Thirty-three percent of underweight patients had died within 5-year follow-up, compared to 34% of patients who were not underweight. There was no significant difference in mortality risk between underweight patients and patients with normal BMIs in our multivariable Cox regression model (adjusted HR 1.57, 95%CI: 0.77-3.20, p = 0.21). Exploratory analyses revealed that a pre-transplant BMI <13 kg/m² was associated with a trend towards increased 5-year mortality (adjusted HR 4.00, 95%CI: 0.87-18.35, p = 0.07).

Conclusions: Our findings suggest that patients with BMIs of 13-17 kg/m² may be candidates for lung transplantation. Large multi-center cohort studies are needed to confirm the lower BMI limit for safely transplanting patients.