Pharmacologic interventions for postoperative nausea and vomiting after thyroidectomy: A protocol for systematic review and network meta-analysis

BACKGROUND: We aimed to perform a network meta-analysis (NMA) to quantify and rank the efficacy and safety of the pharmacologic interventions for prophylactic use for postoperative nausea and vomiting (PONV) in patients undergoing thyroidectomies. METHODS: A systematic and comprehensive search will be performed using MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), and Google Scholar, beginning from their inceptions to February 2019. Only randomized clinical trials on the efficacy and safety of pharmacologic interventions for prophylactic use in patients undergoing thyroidectomies will be included. The primary endpoints will be the incidences of postoperative nausea (PON), postoperative vomiting (POV), and PONV in the early, middle, late, and overall phases. The severity of PON, POV, and PONV; the use of rescue antiemetics; the incidence of complete response; and safety issues, such as headache, dizziness, drowsiness, and constipation, will be also assessed. We will conduct both pairwise meta-analysis and NMA. We will use surface under the cumulative ranking curve (SUCRA) values and rankograms to present the hierarchy of pharmacologic interventions. A comparison-adjusted funnel plot will be used to assess the presence of small-study effects. The quality of the studies included will be assessed using the risk of bias tool 2.0. All statistical analyses will be performed using Stata SE version 15.0. RESULTS: The results of this systematic review and NMA will be published in a peer-reviewed journal. CONCLUSION: This systematic review and NMA will provide a comprehensive and convincing evidence summary of prophylactic pharmacologic interventions for PONV after a thyroidectomy. TRIAL REGISTRATION NUMBER: CRD42018100002.