Characteristics and outcomes of lean versus non-lean metabolic dysfunction-associated steatohepatitis liver...

Metabolic dysfunction-associated steatohepatitis (MASH) is a leading indication for liver transplantation (LT) in the United States, yet outcomes among lean MASH recipients remain poorly defined. Lean patients represent a biologically distinct phenotype with lower body mass index but comparable metabolic risk, making characterization of post-transplant outcomes critical for candidate selection and counseling.

Using United Network for Organ Sharing data from 1/1/2010-9/30/2025, we identified adult LT recipients with MASH/NASH and classified them as lean (BMI <25 kg/m² for non-Asian and <23 kg/m² for Asian patients) or non-lean. Donor, recipient, operative, and waitlist characteristics were compared. Kaplan-Meier methods assessed graft and patient survival, and multivariable Cox regression evaluated 1-year mortality.

Among 19,756 adult MASH/NASH recipients, 2,426 (12.3%) were lean. Lean candidates on the waitlist experienced a lower cumulative incidence of transplantation (sHR 0.94, 95% CI 0.90-0.99, p=0.018) and significantly lower patient survival in lean recipients (1-year: 90.1% vs. 92.2%, p<0.01; 3-year: 83.6% vs. 86.8%, p<0.01; 5-year: 78.2% vs. 82.1%, p<0.01). On multivariable Cox regression, the lean phenotype was associated with higher 1-year mortality (HR 1.33, 95% CI 1.08-1.64, p<0.01).

Lean MASH represents a high-risk phenotype with lower transplant access and worse post-transplant survival, warranting tailored evaluation, optimization, and post-transplant surveillance.