FMO Score for Identifying At-Risk MASH in Obesity: Hepatology | July 2026

Introduction:

Identifying patients with at-risk metabolic dysfunction–associated steatohepatitis (MASH) is essential because they carry a substantially higher risk of cirrhosis, hepatocellular carcinoma, and liver-related mortality. Although liver biopsy remains the diagnostic standard, it is impractical for routine screening in obesity. This study developed and validated a simple, noninvasive score using routinely available laboratory parameters to identify at-risk MASH in individuals with obesity.

Why was this study needed?

. At-risk MASH is associated with increased liver-related and overall mortality.

. Liver biopsy is invasive and unsuitable for large-scale screening.

. Existing noninvasive scores have limited accuracy for identifying at-risk MASH in obesity.

. A simple, inexpensive tool could improve patient selection for specialist evaluation and emerging therapies.

Results:

Using biopsy-confirmed data from nearly 2,000 individuals undergoing bariatric surgery, investigators developed the Fibrotic/at-risk MASH in Obesity (FMO) score, incorporating four routinely measured laboratory parameters: AST, ALT, triglycerides, and HDL cholesterol. The model demonstrated consistently high diagnostic accuracy across multiple external validation cohorts, including the UK Biobank and NHANES. It also predicted long-term severe liver-related outcomes, including cirrhosis and hepatocellular carcinoma, during extended follow-up. Two clinically useful thresholds were identified: a low cutoff with excellent sensitivity and negative predictive value for excluding at-risk MASH, and a higher cutoff with high specificity for identifying patients likely to have advanced disease. Overall, the FMO score outperformed several existing noninvasive models.

Clinical Impact:

The FMO score offers a practical and cost-effective approach for screening individuals with obesity for at-risk MASH using routine laboratory tests. It may reduce unnecessary liver biopsies, improve referral of high-risk patients for specialist care, and facilitate enrollment into clinical trials evaluating emerging MASH therapies. The score also has potential utility in longitudinal risk assessment for liver-related complications.

Bottom Line:

The FMO score is a simple, inexpensive, and accurate noninvasive tool for identifying at-risk MASH in individuals with obesity, with strong diagnostic performance and the ability to predict future severe liver-related outcomes.