A systematic review and meta-analysis of baseline risk factors for the development of postoperative ileus in patients undergoing gastrointestinal surgery.

IntroductionPostoperative ileus occurs frequently following abdominal surgery. Identification of groups at high risk of developing ileus before surgery may allow targeted interventions. This review aimed to identify baseline risk factors for ileus.MethodsA systematic review was conducted with reference to PRISMA and MOOSE guidelines. It was registered on PROSPERO (CRD42017068697). Searches of MEDLINE, EMBASE and CENTRAL were undertaken. Studies reporting baseline risk factors for the development of postoperative ileus based on cohort or trial data and published in English were eligible for inclusion. Dual screening of abstracts and full texts was undertaken. Independent dual extraction was performed. Bias assessment was undertaken using the quality in prognostic studies tool. Meta-analysis using a random effects model was undertaken where two or more studies assessed the same variable.FindingsSearches identified 2,430 papers, of which 28 were included in qualitative analysis and 12 in quantitative analysis. Definitions and incidence of ileus varied between studies. No consistent significant effect was found for association between prior abdominal surgery, age, body mass index, medical comorbidities or smoking status. Male sex was associated with ileus on meta-analysis (odds ratio 1.12, 95% confidence interval 1.02-1.23), although this may reflect unmeasured factors. The literature shows inconsistent effects of baseline factors on the development of postoperative ileus. A large cohort study using consistent definitions of ileus and factors should be undertaken.