Differential Mortality Outcomes in Real-world Patients with Lean, Nonobese, and Obese Nonalcoholic Fatty Liver Disease

Background and Aims: Nonalcoholic fatty liver disease (NAFLD) is commonly associated with obesity but can develop in normal-weight people (lean NAFLD). We compared outcomes in lean, overweight, and obese NAFLD.Methods: This retrospective chart review included patients at Stanford University Medical Center with NAFLD confirmed by imaging between March 1995 and December 2021. Lean, overweight, and obese patients had body mass index of <25.0, >25.0 and <29.9, and >= 30.0 kg/m(2) for non-Asian and >23.0 and >= 27.5 for overweight and obese Asian patients.Results: A total of 9061 lean (10.2%), overweight (31.7%), and obese (58.1%) patients were included. Lean patients were 5 years older than obese patients (53 +/- 17.4 vs. 48.7 +/- 15.1 years), more were female (59.6% vs. 55.2%), white (49.1% vs. 46.5%), had NASH (29.2% vs. 22.5%), cirrhosis (25.3% vs.19.2%), or nonliver cancer (25.3% vs. 18.3%). Fewer had diabetes (21.7% vs. 35.8%) or metabolic comorbidities (all p<0.0001). Lean NAFLD patients had liver-related mortality similar to other groups but higher overall (p=0.01) and nonliver-related (p=0.02) mortality. After multivariable model adjustment for covariates, differences between lean and obese NAFLD in liver-related, nonliver-related, and overall mortality (adjusted hazard ratios of 1.34, 1.00, and 1.32; p=0.66, 0.99, and 0.20, respectively) were not significant.Conclusions: Lean NAFLD had fewer metabolic comorbidities but similar adverse or worse outcomes, suggesting that it is not benign. Healthcare providers should provide the same level of care and intervention as for overweight and obese NAFLD.