Postoperative Complications Associated with Preoperative Hypoalbuminaemia in Gastrointestinal Surgery Patients: A Systematic Review and Meta-Analysis

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BACKGROUND: Gastrointestinal surgery is associated with significant postoperative morbidity. Serum albumin, an inexpensive biomarker that reflects nutritional reserve and systemic inflammation, may help identify at-risk patients. The prognostic value of hypoalbuminaemia in gastrointestinal surgery is not well defined. We aimed to evaluate the association between preoperative hypoalbuminaemia and postoperative outcomes in gastrointestinal surgery. METHODS: We searched MEDLINE, Embase, and two Cochrane databases from inception to July 25, 2025 (PROSPERO: CRD420251130909) for studies comparing adverse outcomes between hypoalbuminaemic and normoalbuminaemic patients. Eligible studies reported at least one postoperative outcome. RESULTS: Across 42 studies, the prevalence of preoperative hypoalbuminaemia was 10.3%, and was lower in bariatric surgery (5.5%) than in non-bariatric surgery populations (17.1%). In hypoalbuminaemic patients, 30-day mortality was more than three-fold higher (RR 3.37, 95% CI 2.59-4.37), all-cause complications were 49% higher (RR 1.49, 1.33-1.68), hospital length of stay was prolonged by 3.02 days (1.63-4.41), and readmission (RR 1.38, 1.22-1.57), reoperation (RR 1.32, 1.22-1.43), and non-home discharge (RR 1.51, 1.28-1.78) were significantly increased. Hypoalbuminaemia was associated with more cardiovascular (RR 1.75, 1.41-2.17), respiratory (RR 2.15, 1.79-2.58), infectious (RR 1.72, 1.47-2.01), and thromboembolic complications (RR 2.00, 1.76-2.27). Between-study heterogeneity was substantial, and prediction intervals were wide. CONCLUSION: Preoperative hypoalbuminaemia is associated with increased mortality, morbidity, and healthcare utilisation in gastrointestinal surgery. As the primary associations derive from unadjusted observational data, preoperative albumin is best interpreted as a marker of perioperative risk rather than a proven modifiable target. Whether interventions that correct hypoalbuminaemia improve postoperative outcomes requires further research.