Graded and threshold effects of body mass index on perioperative outcomes after pancreaticoduodenectomy: a meta-analysis incorporating an institutional cohort

Background The influence of body mass index (BMI) on perioperative results after pancreaticoduodenectomy (PD) remains controversial. This study aimed to clarify how different BMI strata influence operative complexity, postoperative morbidity, and mortality. Methods We performed a meta-analysis and systematic review of 25 studies, including one institutional cohort, evaluating BMI-related perioperative and survival outcomes in patients undergoing PD. The outcomes assessed included operative time, estimated blood loss, postoperative complications, clinically relevant pancreatic fistula, reoperation, perioperative mortality, and overall survival. Results BMI ≥25 kg/m 2 was linked to prolonged operative time, higher blood loss, and a greater risk of postoperative complications, including clinically relevant pancreatic fistula, delayed gastric emptying, and major complications, without a significant increase in perioperative mortality. In contrast, BMI ≥30 kg/m 2 was associated with an increased risk of perioperative mortality. Analyses across BMI categories demonstrated a progressive increase in operative complexity with increasing BMI, whereas perioperative mortality exhibited a threshold pattern, with a marked increase observed primarily at BMI ≥30 kg/m 2 . No notable relationship was found between BMI and long-term overall survival. Conclusions Overweight (BMI ≥25 kg/m 2 ) is primarily associated with increased operative complexity and moderate morbidity, whereas obesity (BMI ≥30 kg/m 2 ) represents a threshold associated with perioperative mortality. These findings support BMI-based risk stratification and may inform individualized perioperative management in patients undergoing PD.