Fibrosis Severity, Not Lean Status, Associated With Prognosis in MASLD

A retrospective observational study reported in JAMA examined 18,326 adults with biopsy-confirmed metabolic dysfunction–associated steatotic liver disease (MASLD) from 41 countries in the Global MASLD project. Researchers compared lean and overweight/obese phenotypes, assessed noninvasive tests for advanced fibrosis, and evaluated all-cause mortality and clinical events, including hepatocellular carcinoma, hepatic decompensation, transplantation, and death. Overall, 6.7% were lean by BMI.

Lean patients had lower prevalences of type 2 diabetes (38.2% vs 48.3%) and advanced fibrosis (29.3% vs 37.2%). Nevertheless, lean status was not independently associated with mortality (adjusted hazard ratio [aHR], 0.90; 95% CI, 0.69–1.16) or clinical events (aHR, 0.94; 95% CI, 0.76–1.17). Advanced fibrosis was associated with higher mortality (aHR, 2.10; 95% CI, 1.71–2.57) and clinical event risk (aHR, 3.41; 95% CI, 2.90–4.03).

For detecting advanced fibrosis, liver stiffness measurement by transient elastography had higher accuracy in lean than overweight/obese patients (area under the curve, 0.87 vs 0.83). FIB-4 accuracy was numerically lower (0.76 vs 0.79), with the confidence interval for the difference reaching zero.

The findings support fibrosis assessment regardless of body size: normal weight did not identify a lower-risk group after adjustment. The retrospective design limits causal interpretation, and the biopsy-confirmed population may not represent all patients with MASLD. Full-text details were unavailable for this update.