Prevalence of High-risk Nonalcoholic Steatohepatitis (NASH) in the United States: Results From NHANES 2017-2018

Background & aims: The population prevalence of high-risk non-alcoholic steatohepatitis (NASH), defined as nonalcoholic fatty liver disease activity score ≥4 and fibrosis stage ≥2, is unknown. The FibroScan-AST (FAST) score, calculated using liver stiffness measurement and controlled attenuation parameter values from FibroScan and aspartate aminotransferase levels, is a validated algorithm to identify individuals with high-risk NASH. We estimated the prevalence of high-risk NASH using the FAST score in the United States population.

Methods: Data were derived from the National Health and Nutrition Examination Surveys 2017-2018, which included a total of 4218 adults with valid elastography measurements. FAST scores of ≥0.35 (sensitivity, 90%) and ≥0.67 (specificity, 90%) were used to identify adults with high-risk NASH in the general population.

Results: At 90% sensitivity for the FAST score, the prevalence of age-adjusted high-risk NASH was 5.8% and was higher among men (8.2% vs 3.6% in women) and in Hispanics (9.2% vs. 5.8% non-Hispanic (N.H.) Asians, 5.2% in N.H. whites, and 3.8% in N.H. blacks). The prevalence of high-risk NASH was 11.7% in those with metabolic syndrome and 22.5% in individuals with type 2 diabetes mellitus (T2DM). At 90% specificity for the FAST score, the prevalence of age-adjusted high-risk NASH was 1.2% and was higher among men (1.7% vs 0.8% in women) and in Hispanics (2.2% vs 1.0% in N.H. Asians, 0.9% in N.H. whites, and 0.4% in N.H. blacks). The prevalence of high-risk NASH was 3.4% in those with metabolic syndrome and 8.7% in adults with T2DM.

Conclusions: We estimate at least 2 million adults have high-risk NASH in the United States. Moreover, the prevalence of high-risk NASH among individuals with T2DM is higher, ranging between 8.7% and 22.5%, supporting the case for coordinated case-finding and management.