Effects of the OPRM 1 A 118 G Polymorphism ( rs 1799971 ) on Opioid Analgesia in Cancer Pain

Materials and Methods: A systematic search of the literature dating to August 31, 2017 was conducted using PubMed, EMBase, Sinomed, and the Cochrane Library databases. The standardized mean difference (SMD) of required amounts of opioids between AA homozygotes and the G-allele was calculated. Subgroup analyses for race and opioid use was performed. In addition, drug sensitivity analysis, heterogeneity description, and publication bias assessment were performed.