Association of Body Mass Index With Mortality and Clinical Outcomes in Patients With Nonalcoholic Fatty Liver Disease: A Medical Information Mart for Intensive Care IV (MIMIC-IV) Cohort Study.

BACKGROUND

Nonalcoholic fatty liver disease is a common condition linked to metabolic disorders and increasing healthcare burden. The relationship between body mass index (BMI) and clinical outcomes in this population remains uncertain, with prior studies reporting mixed findings.

OBJECTIVE

This study aimed to evaluate the association between BMI and in-hospital mortality among adults with nonalcoholic fatty liver disease, with BMI analyzed as a binary variable (underweight or normal weight vs overweight or obese).

METHODS

This retrospective cohort study used data from the Medical Information Mart for Intensive Care IV (MIMIC-IV) version 3.1 database. Adult patients aged 18 years or older with nonalcoholic fatty liver disease were identified using the International Classification of Diseases (ICD) codes, and only the first hospital admission was included. BMI was calculated from recorded height and weight and categorized as underweight or normal weight versus overweight or obese. Multivariable logistic regression was used to estimate adjusted odds ratios for in-hospital mortality. Due to the low number of mortality events, a parsimonious model was applied to reduce overfitting, including age, sex, race, coronary artery disease, and chronic kidney disease as covariates.

RESULTS

A total of 2,955 patients were included. In-hospital mortality was low, with 15 deaths observed. Overweight or obese BMI was not significantly associated with mortality compared to underweight or normal-weight BMI (adjusted odds ratio: 0.42; 95% CI: 0.14-1.27; p=0.124). Increasing age was associated with higher mortality (adjusted odds ratio: 1.05 per year; 95% CI: 1.01-1.10; p=0.024). No significant associations were observed for sex, race, coronary artery disease, or chronic kidney disease.

CONCLUSION

BMI was not associated with in-hospital mortality in patients with nonalcoholic fatty liver disease. Age was associated with increased mortality risk. These findings support the need to consider broader clinical factors beyond BMI in risk assessment.