Impact of Body Mass Index on outcomes of abdominal aortic aneurysm repair: a systematic review and meta-analysis

BACKGROUND: The influence of Body Mass Index (BMI) on outcomes after abdominal aortic aneurysm (AAA) repair remains controversial. While the 'obesity paradox' is generally noted for other cardiovascular diseases, evidence from vascular surgery is limited. This systematic review evaluated the impact of BMI on mortality and postoperative complications following AAA repair. METHODS: The databases of PubMed, Embase, Scopus, and Web of Science were explored up to 13 October 2025 for studies comparing outcomes across BMI categories in adults undergoing open or endovascular AAA repair. Random-effects meta-analyses were conducted. Sensitivity analyses, subgroup analyses by surgical approach and follow-up duration, and Egger's test for publication bias were performed. RESULTS: Twelve retrospective cohort studies were included. Mortality meta-analysis demonstrated a J-shaped association between BMI and mortality risk: overweight and obese patients had lower mortality than normal-weight individuals, while underweight patients exhibited higher mortality. Sensitivity analyses mostly confirmed the robustness of findings. Subgroup analyses revealed variable effects across open and endovascular repair, as well as different follow-up durations. Egger's test revealed no evidence of publication bias. Secondary outcome analysis showed comparable rates of most perioperative complications across BMI groups, with lower cardiac events among overweight and obese patients. CONCLUSIONS: The present evidence suggests that a higher BMI may not be associated with increased mortality risk and appears to confer a survival benefit after AAA repair, whereas underweight status predicts poorer survival outcomes. The risk of other complications does not appear to differ across BMI groups.