High mortality rates prove lean patients with NAFLD should ‘be taken seriously’
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Lean patients with nonalcoholic fatty liver disease had significantly higher mortality than non-lean patients, despite having lower rates of cirrhosis and diabetes, according to research in Alimentary Pharmacology & Therapeutics.
“While NAFLD is strongly associated with overweight/obesity, up to 20% of patients with NAFLD have normal BMI,” Vincent L. Chen, MD, assistant professor of gastroenterology and internal medicine at the University of Michigan, told Healio. “There is still much we do not know about these so-called ‘lean NAFLD’ patients.”
To better understand how NAFLD differs in lean individuals compared with those with obesity or who are overweight, Chen and colleagues conducted a retrospective study of adults with NAFLD at the University of Michigan Health System between January 2012 and December 2021. Researchers analyzed mortality rates between groups, as well as new diagnoses of cirrhosis, cardiovascular disease, diabetes and cancer.
Chen and colleagues included 18,594 patients for cross-sectional analysis and 13,420 patients for longitudinal analysis. Approximately 11% of patients in the entire cohort were lean, 25% were overweight, 28% had class 1 obesity and 35% had class 2 to 3 obesity. The median age of participants was 51 years and more than half (54.6%) were women.
According to results, lean patients had lower prevalence of any metabolic disease (39.5% vs. 52.6% vs. 57.2% vs. 60.2%, respectively), cirrhosis (1.3% vs. 1.3% vs. 1.5% vs. 2.5%) and diabetes (13.5% vs. 17.7% vs. 21.7% vs. 30.2%) at baseline, but no difference in cardiovascular disease, any cancer or obesity-related cancer during follow-up (mean, 49.3 months).
During this time, 616 patients died with an incidence of 16.67, 10.11, 7.37 and 8.99, respectively, per 1,000 person-years. After adjusting for confounders, researchers reported that overweight patients (adjusted HR = 0.54; 95% CI, 0.42-0.69), those with class 1 obesity (aHR = 0.4; 95% CI, 0.31-0.52) and those with class 2 to 3 obesity (aHR = 0.52; 95% CI, 0.41-0.66) had “significantly lower” mortality compared with lean patients.
“It is possible that the reason these patients were ‘lean’ is that they had medical conditions causing them to lose weight, and those underlying conditions are why they had higher mortality,” Chen said. “We did our best to account for this possibility, but future studies could look into this in more detail.”
He added, “Sometimes medical providers discount lean NAFLD as more ‘benign’ than NAFLD in obesity/overweight. Our findings show that lean NAFLD should still be taken seriously by medical providers.”
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