Progression to cirrhosis is similar among all ages in nonalcoholic fatty liver disease, but liver-related events increase with age

Background: NAFLD is increasingly common among young people. Whether NAFLD carries a more benign course in younger adults is not known. We aimed to characterize genetic and metabolic risk factors for NAFLD and their effects on disease progression across age groups. Methods: We conducted a retrospective study of adults with NAFLD seen within Michigan Medicine, a tertiary care center, between 2010 and 2021. NAFLD was defined by hepatic steatosis on imaging, biopsy, or transient elastography in the absence of other chronic liver diseases. Cirrhosis was determined by validated International Classification of Diseases-9/10 codes or imaging. Fine-Gray competing risk models were generated, with incident cirrhosis and liver-related events (LREs) as the primary outcomes and death without cirrhosis or LREs as a competing risk. The primary predictor was the age category. Results: We included 31,505 patients with NAFLD, with 8,252 aged 18 to younger than 40, 15,035 aged 40 to younger than 60, and 8,218 aged 60 years or older years at diagnosis. Compared with older patients, young adults more often had obesity, higher ALT, and high-risk PNPLA3 alleles, and fewer had prevalent cirrhosis, hypertension, hyperlipidemia, and diabetes. The 10-year risk of incident cirrhosis was similar between ages (3.4% in age 18 to <40 vs 3.7% in age 40 to <60 vs 4.7% in age >= 60; p = 0.058). Predictors of LREs were advancing age and diabetes, with a significantly higher 10-year risk of LREs in the oldest age group (0.2% in age 18 to <40 vs 0.7% in age 40 to <60 vs 1.1% in age >= 60; p = 0.008). Conclusions: While the baseline prevalence of cirrhosis was higher older adults, the rate of NAFLD progression to cirrhosis was similar in young and older adults. Older patients were more likely to have LREs.