The Effect of Genetic Variation on the Sensitivity to Opioid Analgesics in Patients With Postoperative Pain: An Updated Meta-analysis.

BACKGROUND:Responsiveness to opioid analgesics differs among patients with acute postoperative pain. OBJECTIVE:Our study presents the most recent evidence on the effect of genetic variations on postoperative pain, opioid consumption, nausea, and vomiting in patients treated with opioids. STUDY DESIGN:An updated systematic review and meta-analysis on the association between single-nucleotide polymorphisms and opioids administered to patients with acute postoperative pain. METHODS:PubMed, Embase, ISI Web of Science, and the Cochrane Library databases were searched for articles published from February 1, 2014, through December 31, 2021. RESULTS:Added to the previous meta-analysis, 39 studies (a total of 7,455 patients) were included in the final meta-analysis. Highlights of the findings include: 1) human μ-opioid receptor gene 118G allele carriers required more opioids during the first postoperative 24 hours (standard mean difference [SMD] = -0.27; 95% CI,-0.40 to -0.14; P < 0.0001) and 48 hours (SMD = -0.52; 95% CI, -0.83 to -0.20; P = 0.001), and reported higher pain scores during the first 24 hours but not at the 48-hour postoperative period (SMD = -0.09, 95% CI, -0.15 to -0.03; P = 0.002) compared to homozygous 118AA patients. 2) patients with the CYP3A4 *1G allele required fewer opioids during the first 24-hour postoperative period (SMD = 0.59; 95% CI, 0.05 to 1.14; P = 0.03) compared to patients with the homozygous CYP3A4*1/*1 allele. 3) Adenosine triphosphate-binding cassette subfamily B member-1 (ABCB1) 3435T allele carriers required more opioids during the 48-hour postoperative period (SMD = -0.21; 95% CI, -0.38 to -0.04; P = 0.02) compared to homozygous CC carriers. 4) Catechol-O-methyl transferase 158A allele carriers required fewer opioids during the first 24-hour postoperative period (SMD = 0.33; 95% CI, 0.15 to 0.51; P = 0.0004) compared to homozygous GG carriers. No significant differences were observed in patients with CYP2D6*10 and ABCB1 G2677A/T genetic polymorphisms. LIMITATIONS:Several loci were not analyzed in detail due to insufficient clinical data. Furthermore, nongenetic factors that affected analgesic efficacy and the clinical outcome of postoperative pain were not discussed and were not the aim of this meta-analysis. CONCLUSIONS:In combination with previous systematic reviews and meta-analyses, our results indicate that the A118G allele variant of OPRM1 and the *1*1G allele variant of CYP3A4 have a profound influence on individual differences in opioid reactivity in patients with postoperative pain. Our results, together with the identification of additional single nucleotide polymorphisms in future studies, may provide a theoretical basis for precise clinical analgesia. KEY WORDS:Single nucleotide polymorphism, postoperative pain, opioid, meta-analysis.