SETTING: Hospital surgical ward.
SUBJECTS: Women (107 Indian, 184 Malay, and 750 Han Chinese) undergoing total hysterectomy surgery.
METHODS: Morphine consumption, preoperative pain, and postoperative pain were evaluated in relation to genetic variability comprising 19 single-nucleotide polymorphisms (SNPs) in 14 genes involved in glial activation, inflammatory signaling, and neuronal regulation, plus OPRM1 (1 SNP) and COMT (3 SNPs).
RESULTS: Pre- and postoperative pain and age were associated with increased and decreased morphine consumption, respectively. In Chinese patients, only 8% of the variability in consumption could be explained by these nongenetic and genetic (BDNF, IL1B, IL6R, CRP, OPRM1, COMT, MYD88) factors. However, in Indian patients, 41% of morphine consumption variability could be explained by age (explaining <3%) and variants in OPRM1 rs1799971, CRP rs2794521, TLR4 rs4986790, IL2 rs2069762, COMT rs4818, TGFB1 rs1800469, and IL6R rs8192284 without controlling for postoperative pain.
CONCLUSIONS: This is the highest known value reported for genetic contributions (38%) to morphine use in the acute postoperative pain setting. Our findings highlight the need to incorporate both genetic and nongenetic factors and consider ethnicity-dependent and nonadditive genotypic models in the assessment of factors that contribute to variability in opioid use.