# Impact of preoperative underweight status on perioperative morbidity and mortality after liver resection for liver tumors: a meta-analysis

## TL;DR

Being underweight before liver surgery increases the risk of complications and death, according to a meta-analysis of 3,835 patients.

## Contribution

This study is the first meta-analysis to systematically evaluate the impact of preoperative underweight status on liver resection outcomes.

## Key findings

- Underweight patients had longer operation times and higher postoperative morbidity and mortality.
- Surgical site infections were more common in underweight patients compared to normal weight patients.
- No significant differences were found in blood loss, length of stay, or bile leak between the groups.

## Abstract

The impact of preoperative underweight status on the outcomes of liver resections for liver tumors is debated. We aimed at conducting a meta-analysis to evaluate the associations between underweight and short-term clinical outcomes after liver resection.

PubMed, Cochrane Library, Embase, Scopus , and Web of Science databases were searched from inception to September 14, 2024 (updated on April 21, 2025) to identify eligible studies. Risk ratios (RRs) or mean differences (MDs) and 95% confidence intervals (CI) were calculated.

Seven studies were included, with a total of 3,835 patients (normal weight group: 3,412 patients; underweight group: 423 patients). Findings indicated that, relative to individuals of normal weight, underweight patients have longer operation time (MD, 7.73 mins; 95% CI [2.08–13.38], P = 0.007) and higher overall postoperative morbidity (RR 1.41 95% CI [1.06–1.88], P = 0.02), mortality (RR 2.98, 95% CI [1.4 3–6.20], P = 0.003), and surgical site infection (RR 2.00, 95% CI [1.03–3.88], P = 0.04). There were no significant differences in blood loss, length of stay, liver failure, bile leak, and blood transfusion between the normal weight and underweight groups.

Preoperative underweight status is associated with higher risk of morbidity and mortality after liver resection. Prospective studies or interventional trials, such as nutritional prehabilitation or stratification by cirrhosis and resection extent, are needed to confirm whether underweight represents a truly modifiable risk factor. This review is intended for professionals within the fields of hepatobiliary surgery.