A meta-analysis of randomised controlled trials on preoperative oral carbohydrate treatment in elective surgery

Background & aims: Whilst preoperative carbohydrate treatment (PCT) results in beneficial physiological effects, the effects on postoperative clinical outcomes remain unclear and were studied in this meta-analysis.

Methods: Prospective studies that randomised adult non-diabetic patients to either PCT (≥50 g oral carbohydrates 2-4 h pre-anaesthesia) or control (fasted/placebo) were included. The primary outcome was length of hospital stay. Secondary outcomes included development of postoperative insulin resistance, complications, nausea and vomiting. Methodological quality was assessed using GRADEpro® software.

Results: Twenty-one randomised studies of 1685 patients (733 PCT: 952 control) were included. No overall difference in length of stay was noted for analysis of all studies or subgroups of patients undergoing surgery with an expected hospital stay ≤2 days or orthopaedic procedures. However, patients undergoing major abdominal surgery following PCT had reduced length of stay [mean difference, 95% confidence interval: -1.08 (-1.87 to -0.29); I² = 60%, p = 0.007]. PCT reduced postoperative insulin resistance with no effects on in-hospital complications over control (risk ratio, 95% confidence interval, 0.88 (0.50-1.53), I² = 41%; p = 0.640). There was significant heterogeneity amongst studies and, therefore, quality of evidence was low to moderate.

Conclusions: PCT may be associated with reduced length of stay in patients undergoing major abdominal surgery, however, the included studies were of low to moderate quality.