OPRM1 A118G Gene Variant And Postoperative Opioid Requirement:A Meta-analysis

Background: Although several studies have indicated the association between the OPRM1 A118 G polymorphism and pain response, however,the results of many studies are not consistent.Methods: We searched English database(Pubmed, EMBASE, MEDLINE) and Chinese database(Chinese Journal Full-text Database, Wanfang database and VIP journals database),the deadline is December 2015.Two authors independently reviewed and selected references.The standardized mean difference(SMD) was used to assess the difference of opioid dose between the AA homozygous and the G- allele carriers.Results: Four hundred seventy-one articles were retrieved.Thirteen articles with 2875 patients were included in this meta- analysis.During the 24-hour postoperative period,results show that compared with genes homozygous wild-type AA patients, Gallele carriers need more opioids during the period of postoperative(SMD,-0.16; P = 0.037).Subgroup analysis of the patients in Asian region(SMD,-0.18; P=0.035), morphine users(SMD,-0.19; P=0.003), and obstetrics and gynecology operation(SMD,-0.29; P=0.006) also have the same conclusion.During the 48-hour postoperative period,results show that compared with genes homozygous wild-type AA patients, G- allele carriers do not need more opioids during the period of postoperative(SMD,-0.29; P = 0.156).Conclusions: Our study showed that: during the 24-hour postoperative period, OPRM1 A118 G single nucleotide polymorphisms were associated with postoperative analgesia, and patients carrying the G- allele increased the requirement of opioids.