# Effect of lean status on the mortality of patients with non-alcoholic fatty liver disease (NAFLD): A systematic review and meta-analysis

## TL;DR

Lean people with non-alcoholic fatty liver disease face higher all-cause and liver-related mortality risks compared to those with high BMI.

## Contribution

This study is the first to systematically analyze the mortality risk differences between lean and non-lean NAFLD patients.

## Key findings

- Lean NAFLD patients had a 34% higher all-cause mortality risk than those with high BMI.
- Lean NAFLD patients had a 114% higher liver disease-related mortality risk compared to those with high BMI.
- Lean NAFLD patients had similar cardiovascular and cancer-related mortality risks as those with high BMI.

## Abstract

To investigate the impact of lean status as per body mass index (BMI) on mortality in cases of non-alcoholic fatty liver disease (NAFLD).

A systematic search was conducted in PubMed, Embase, and Scopus to identify relevant studies published from the inception of each database up to July 31, 2024. Observational studies that reported data on the mortality outcomes of NAFLD patients with different BMI, and provided adjusted estimates were included. The Newcastle-Ottawa Scale (NOS) was used for quality assessment. Pooled effect sizes were reported as hazard ratio (HR) with 95% confidence intervals (CI).

Fourteen studies were included, of which majority were retrospective cohort studies (n=10). Objective assessment method for NAFLD i.e., imaging and/or biopsy was used in 10 studies. Compared to NAFLD patients with high BMI, lean patients had higher risk of all-cause mortality (HR 1.34, 95% CI: 1.23, 1.47), with no publication bias for any of the outcomes. Lean status correlated with elevated risk of liver disease-related mortality (HR 2.14, 95% CI: 1.18, 3.87) but had similar risk of cardiovascular (HR 0.92, 95% CI: 0.65, 1.30) and cancer-related mortality (HR 1.20, 95% CI: 0.90, 1.60).

Lean status of NAFLD patients correlates with higher risk of all-cause and liver disease-related mortality compared to patients with high BMI. There is a need for tailored interventions and further research to understand specific mortality risks in this subgroup of patients.