The impact of preoperative glycated hemoglobin (HbA1c) on postoperative complications after elective major abdominal surgery: a meta-analysis.

Abstract

Background\nDiabetes is a risk factor for postoperative complications. Prior meta-analyses have shown that elevated glycated hemoglobin (HbA1c) is associated with postoperative complications in various surgical populations. However, no meta-analysis has investigated this association in elective major abdominal surgery patients. This is the first meta-analysis to investigate the association between preoperative HbA1c and postoperative complications in this unique population.\n\n\nMethods\nPRISMA guidelines were adhered to. Six databases were searched up to 1st April 2020. Primary studies investigating the effect of HbA1c on postoperative complications in elective major abdominal surgery patients were included. Risk of bias and quality of evidence assessment of the studies were performed. Data was pooled using a random-effects model. Meta-regression was performed to evaluate the effect of different HbA1c cut-off values.\n\n\nResults\n12 observational studies (25036 patients) were included. Most studies scored good and moderate quality using NOS and GRADE respectively. Patients with high HbA1c had a higher risk of anastomotic leaks (OR 2.80, 95%CI 1.63-4.83, p<0.001), wound infections (OR 1.21, 95%CI 1.08-1.36, p=0.001), major complications defined as Clavien-Dindo 3-5 (OR 2.16, 95%CI 1.54-3.01, p<0.001), and overall complications defined as Clavien-Dindo 1-5 (OR 2.12, 95%CI 1.48-3.04, p<0.001).\n\n\nConclusions\nThis meta-analysis shows that HbA1c 6-7% is associated with higher risks of anastomotic leaks, wound infections, major complications and overall postoperative complications. Guidelines currently using HbA1c thresholds >7% may therefore be conducting elective surgery on pre-optimised patients. A randomized controlled trial should be conducted to explore if this association is causative before policy changes are made.