Impact of body mass index on disease progression and outcomes in patients with nonalcoholic fatty liver disease

Abstract Background The relationship between body mass index (BMI) and outcomes in patients with nonalcoholic fatty liver disease (NAFLD) is not well defined. This study aimed to assess the presentations, outcomes, and development of liver-related events (LREs) and non-LREs in patients with NAFLD stratified by BMI. Methods Records of NAFLD patients from 2000–2022 were reviewed. Patients were categorized as lean (18.5–22.9 kg/m2), overweight (23–24.9 kg/m2), and obese (>25 kg/m2) based on BMI. Stage of steatosis, fibrosis, and NAFLD activity score were noted in the patients undergoing liver biopsy in each group. Results Out of 1051 NAFLD patients, 127 (12.1%) had normal BMI, 177 (16.8%) and 747 (71.1%) were overweight and obese, respectively. Median [interquartile range] BMI was 21.9 [20.6–22.5], 24.2 [23.7–24.6], and 28.3 [26.6–30.6] kg/m2 in each group, respectively. Prevalence of metabolic syndrome and dyslipidemia were significantly higher in the obese. Obese patients had significantly higher median [interquartile range] liver stiffness (6.4 [4.9–9.4] kPa) than overweight and lean subjects. A higher proportion of obese patients had significant and advanced liver fibrosis. At follow-up, there were no significant differences in the progression of liver disease, new LREs, coronary artery disease, or hypertension across the BMI groups. Overweight and obese patients were more likely to develop new-onset diabetes by follow-up. The mortality rates in the three groups were comparable (0.47, 0.68, and 0.49 per 100 person-years, respectively), with similar causes of death (liver-related vs non-liver-related). Conclusions Patients with lean NAFLD have similar disease severity and rates of progression as the obese. BMI is not a reliable determinant of outcomes in NAFLD patients. Key messages What is already known on this topic What this study adds How this study might affect research, practice, or policy