A new study, now published in JAMA, comes from the Global MASLD (G-MASLD) project, launched in 2023 by the Global NASH/MASH Council (GNC). Led by Dr. Zobair Younossi, the project brought together more than 60 investigators from 41 countries across Asia, Europe, the Middle East and North Africa, Latin America, and North America. The result is one of the largest biopsy-confirmed MASLD cohorts ever assembled, with more than 18,000 patients. Answering questions of this scale and diversity requires sustained international partnership carried out by the GNC.
The findings show that normal weight does not mean lower risk. About 6.7% of patients were lean by BMI (6% by waist circumference), rising to around 11% in Asia. Lean patients had fewer metabolic comorbidities and milder histologic activity, yet nearly 30% already had advanced fibrosis. Lean status was not independently associated with mortality or clinical events, but the presence of advanced fibrosis was the strongest predictor of outcomes: it roughly doubled mortality risk (aHR 2.10) and more than tripled the risk of clinical events (aHR 3.41). Liver stiffness measurement performed well in lean patients (AUC 0.87), while FIB-4 was less reliable (AUC 0.76). The clinical message is clear. Fibrosis assessment and risk stratification should guide care for every patient with MASLD regardless of BMI, and lean patients belong in therapeutic trials and treatment decisions.
Congratulations to all the Global MASLD project colleagues and collaborators from around the world who contributed to this effort.
doi:10.1001/jama.2026.18491
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