Topical application of licorice for prevention of postoperative sore throat in adults: A systematic review and meta-analysis

STUDY OBJECTIVE: Postoperative sore throat negatively affects patient satisfaction and recovery. It may be related to inflammation of the mucosa caused by injury during intubation. Licorice, derived from the root of Glycyrrhiza glabra, contains active anti-inflammatory ingredients. The efficacy and safety of topical licorice for preventing postoperative sore throat in adults undergoing tracheal intubation for general anesthesia were assessed by a systematic review and meta-analysis. DESIGN: A systematic review and meta-analysis of randomized controlled trials. SETTING: Trials conducted in perioperative settings. MEASUREMENTS: PubMed, EMBASE, Web of Science, Scopus, and the Cochrane Central Register of Controlled Trials were searched from inception to April 21, 2018. All randomized, controlled trials (RCTs) that assessed the efficacy and safety of topical licorice in adults undergoing elective surgery under general anesthesia were eligible. The risk of bias was evaluated using the Cochrane risk of bias assessment tool. Data were pooled using a random-effects model. We conducted a trial sequential analysis (TSA) on the incidence of postoperative sore throat. Primary outcomes were the incidence and severity of sore throat 24 h after surgery/extubation and adverse events. MAIN RESULTS: Five randomized controlled trials involving 609 patients were included. Compared with non-analgesic control, topical licorice was associated with a reduced incidence (risk ratio, 0.44; 95% confidence interval (CI), 0.28-0.69; P < 0.001) and severity (standardized mean difference, -0.69; 95% CI, -0.96, -0.43; P < 0.001) of postoperative sore throat. Four trials reported adverse events; there were no significant adverse events related to topical licorice. The findings of sensitivity analyses excluding trials at high or unclear risk of each type of bias were consistent with these findings. TSA confirmed the evidence for postoperative sore throat was adequate. CONCLUSIONS: Preoperative topical application of licorice appears significantly more effective than nonanalgesic methods for preventing postoperative sore throat.