Network meta-analysis of the effect of preoperative carbohydrate loading on recovery after elective surgery

Background: Three meta-analyses have summarized the effects of preoperative carbohydrate administration on postoperative outcomes in adult patients undergoing elective surgery. However, these studies could not account for the different doses of carbohydrate administered and the different controls used. Multiple-treatments meta-analysis allows robust synthesis of all available evidence in these situations. Methods: Article databases were searched systematically for RCTs comparing preoperative carbohydrate administration with water, a placebo drink, or fasting. A four-treatment multiple-treatments meta-analysis was performed comparing two carbohydrate dose groups (low, 10-44 g; high, 45 g or more) with two control groups (fasting; water or placebo). Primary outcomes were length of hospital stay and postoperative complication rate. Secondary outcomes included postoperative insulin resistance, vomiting and fatigue. Results: Some 43 trials involving 3110 participants were included. Compared with fasting, preoperative low-dose and high-dose carbohydrate administration decreased postoperative length of stay by 0.4 (95 per cent c. i. 0.03 to 0.7) and 0.2 (0.04 to 0.4) days respectively. There was no significant decrease in length of stay compared with water or placebo. There was no statistically significant difference in the postoperative complication rate, or in most of the secondary outcomes, between carbohydrate and control groups. Conclusion: Carbohydrate loading before elective surgery conferred a small reduction in length of postoperative hospital stay compared with fasting, and no benefit in comparison with water or placebo.