Metabolic syndrome; associations with adverse outcome after colorectal surgery. A systematic review and meta-analysis

BACKGROUND: Increasing evidence shows that patients with Metabolic Syndrome (MetS) are at risk for adverse outcome after abdominal surgery. The aim of this study was to investigate the impact of MetS and preoperative hyperglycemia, as an individual component of MetS, on adverse outcome after colorectal surgery. METHODS: A literature review was systematically performed according to the PRISMA guidelines. Inclusion criteria were observational studies that evaluated the relationship between MetS or preoperative hyperglycemia and outcomes after colorectal surgery (i.e. any complication, severe complication defined as Clavien-Dindo grade ≥ III, anastomotic leakage, surgical site infection, mortality and length of stay). RESULTS: Six studies (246.383 patients) evaluated MetS and eight studies (9.534 patients) reported on hyperglycemia. Incidence rates of MetS varied widely from 7% to 68% across studies. Meta-analysis showed that patients with MetS are more likely to develop severe complications than those without MetS (RR 1.62, 95% CI 1.01–2.59). Moreover, a non-significant trend toward increased risks for any complication (RR 1.35, 95% CI 0.91–2.00), anastomotic leakage (RR 1.67, 95% CI 0.47–5.93) and mortality (RR 1.19, 95% CI 1.00–1.43) was found. Furthermore, preoperative hyperglycemia was associated with an increased risk of surgical site infection (RR 1.35, 95% CI 1.01–1.81). CONCLUSION: MetS seem to have a negative impact on adverse outcome after colorectal surgery. As a result of few studies meeting inclusion criteria and substantial heterogeneity, evidence is not conclusive. Future prospective observational studies should improve the amount and quality in order to verify current results.