Analysis of SCN9A Gene Variants for Acute and Chronic Postoperative Pain and Morphine Consumption After Total Hysterectomy.

Abstract

Single nucleotide polymorphisms (SNPs) of the voltage-gated sodium channel alpha subunit gene (SCN9A) have been associated with pain in various settings. The aim of this study was to investigate the association of the SNPs to evaluate the influence of common gene variants on chronic postoperative pain (CPSP) and other related pain variables in a cohort of patients who underwent a scheduled hysterectomy. DNA samples from a cohort of 1,075 patients who underwent a scheduled total hysterectomy in our hospital were genotyped for three common SCN9A SNPs using TaqMan assays. Multivariate logistic regression models were used to quantify the association between independent covariates such as pain threshold, pain endurance, pain scores, morphine use, and the presence of chronic pain. Frequencies of the minor alleles were different between the different ethnic groups. There was a statistically significant association of rs16851799 with morphine consumption and self-reported postoperative pain for the 1,038 subjects genotyped, with the TT genotype reporting higher pain and using more morphine. For the subpopulation of 446 subjects with chronic pain data, there was a similar association with self-reported postoperative pain and tolerance of pressure pain. Univariate analysis also showed a statistically significant association of rs16851799 with CPSP, whereas multivariable analysis revealed a similar association of rs4387806 with this outcome. There were three haplotypes with different relative frequencies for the CPSP and non-CPSP groups. Our results showed that SCN9A polymorphisms could play a role in acute pain perception and the susceptibility to chronic pain.