Association of catechol-O-methyltransferase val158Met polymorphism with postoperative analgesic opioid use

This meta-analysis was performed to assess the effects of COMT rs4860 polymorphism on postoperation analgesia with opioid consumption. We conducted a search of all papers using PubMed, the Cochrane Library, EMbase, Ovid, Web of Science, Google (scholar), Chongqing VIP database, CBMDisc, and CNKI database. The fixed or random effect model was determined according to the heterogeneity among researches. The crude standardized mean difference (SMD) with 95% confidence interval (CI) was calculated. Publication bias was estimated using funnel plots and Begg's and Egger's test. Five studies involving 517 cases were included in this meta-analysis. The results indicated that cases with AA homozygote of the COMT rs4860 polymorphism required less opioid doses to achieve adequate pain relief, compared with those carrying the G allele (AG+GG) in 24 h after operation (SMD=-0.33, 95% CI -0.56, -0.10, P=0.005). Nevertheless, there were no statistically significant differences between an AA homozygote and a G carrier (AG+GG) in opioid doses in 48 h after operation (SMD=-0.01, 95% CI -0.35, 0.33, P=0.94) and pain score at 24 h after operation (SMD=-0.09, 95% CI -0.33, 0.15, P=0.47). There were no statistically significant differences between an AA homozygote and a G carrier (AG+GG); Future studies should be undertaken to ascertain any contribution of this polymorphism in opioid consumption in postoperative conditions.