The acute surgical unit: An updated systematic review and meta-analysis

Objective: To systematically review comparative studies on the acute surgical unit (ASU) model. Methods: Searches were performed of Cochrane, Embase, Medline and grey literature. Eligible articles were comparative studies of the Acute Surgical Unit (ASU) model published 01/01/2000-12/03/2020. Amongst patients with any diagnosis, primary outcomes were length of stay, after-hours operating, complications and cost. Secondary outcomes were time to surgical review, time to theatre, mortality and re-admission for patients with any diagnosis, and cholecystectomy during index admission for patients with biliary disease. Additional analyses were planned for specific cohorts, such as patients with appendicitis or cholecystitis. Results: Searches returned 9,677 results from which 77 eligible publications were identified, representing 150,981 unique patients. Cohorts were adequately homogenous for meta-analysis of all outcomes except cost. For patients with any diagnosis, compared with the Traditional model, the introduction of an ASU model was associated with reduced length of stay (mean difference [MD] 0.68 days; 95% confidence interval [CI] 0.38-0.98), after-hours operating rates (odds ratio [OR] 0.56; 95% CI 0.46-0.69) and complications (OR 0.48, 95% CI 0.33-0.70). Regarding cost, two studies reported savings following ASU introduction, while one found no difference. Amongst secondary outcomes, for patients with any diagnosis, ASU commencement was associated with reduced time to surgical review, time to theatre and mortality. Re-admissions were unchanged. For patients with biliary disease, ASU establishment was associated with superior rates of index cholecystectomy. Conclusion: Compared to the Traditional structure, the ASU model is superior for most metrics. ASU introduction should be promoted in policy for widespread benefit.