Common variants of catechol-O-methyltransferase influence patient-controlled analgesia usage and postoperative pain in patients undergoing total hysterectomy

Pharmacogenetic Approaches in Personalized Medicine for Postoperative Pain Management

Despite technical and pharmacological advancements in recent years, including optimized therapies and personalized medicine, postoperative pain management remains challenging and sometimes undertreated. This review aims to summarize and update how genotype-guided therapeutics within personalized medicine can enhance postoperative pain management. Several studies in the area have demonstrated that genotype-guided therapy has the ability to lower opioid consumption and improve postoperative pain. Gene mutations, primarily OPRM1, CYP2D6, CYP2C9, COMT and ABCB1, have been shown to exert nuanced influences on analgesic response and related pharmacological outcomes. This review underscores the integration of pharmacogenetic-guided personalized medicine into perioperative care, particularly when there is uncertainty regarding opioid prescriptions. This approach leads to superior outcomes in terms of postoperative pain relief and reduced morbidity for numerous patients.

Association of Genetic Variants with Postsurgical Pain: A Systematic Review and Meta-analyses

BACKGROUND

Postsurgical pain is a key component of surgical recovery. However, the genetic drivers of postsurgical pain remain unclear. A broad review and meta-analyses of variants of interest will help investigators understand the potential effects of genetic variation.

METHODS

This article is a systematic review of genetic variants associated with postsurgical pain in humans, assessing association with postsurgical pain scores and opioid use in both acute (0 to 48 h postoperatively) and chronic (at least 3 months postoperatively) settings. PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched from 2000 to 2022 for studies using search terms related to genetic variants and postsurgical pain in humans. English-language studies in adult patients examining associations of one or more genetic variants with postsurgical pain were included. The primary outcome was association of genetic variants with either acute or chronic postsurgical pain. Pain was measured by patient-reported pain score or analgesic or opioid consumption.

RESULTS

A total of 163 studies were included, evaluating 129 unique genes and 594 unique genetic variants. Many of the reported significant associations fail to be replicated in other studies. Meta-analyses were performed for seven variants for which there was sufficient data (OPRM1 rs1799971; COMT rs4680, rs4818, rs4633, and rs6269; and ABCB1 rs1045642 and rs2032582). Only two variants were associated with small differences in postsurgical pain: OPRM1 rs1799971 (for acute postsurgical opioid use standard mean difference = 0.25; 95% CI, 0.16 to 0.35; cohort size, 8,227; acute postsurgical pain score standard mean difference = 0.20; 95% CI, 0.09 to 0.31; cohort size, 4,619) and COMT rs4680 (chronic postsurgical pain score standard mean difference = 0.26; 95% CI, 0.08 to 0.44; cohort size, 1,726).

CONCLUSIONS

Despite much published data, only two alleles have a small association with postsurgical pain. Small sample sizes, potential confounding variables, and inconsistent findings underscore the need to examine larger cohorts with consistent outcome measures.

EDITOR’S PERSPECTIVE

Genetic risk factors for chronic postsurgical pain in children: A narrative review

Genetic risk factors for chronic postsurgical pain in adults have been established, but little is known whether the same associations exist in children. It is even less clear how much influence single nucleotide polymorphisms can exert on the phenotypic expression of chronic postsurgical pain in children in general. To this effect, a search was made for original articles which met the following criteria: evaluation of postsurgical pain in children with known genetic mutations or, conversely, evaluation of atypical pain trajectories of postsurgical children assessing for possible genetic mutations that may explain the phenotype. All titles and abstracts retrieved were reviewed for suitability for inclusion. The references of the selected articles were also checked for additional relevant papers. To assess the transparency and quality of the genetic studies both STrengthening the REporting of Genetic Association studies scores and Q-Genie scores were applied. Overall, there is a paucity of information regarding the link between genetic mutations and eventual chronic postsurgical pain development although there is some information on acute postoperative pain. Evidence has shown that the contribution of genetic risk factors to chronic postsurgical pain development appears to be minor, with its clinical relevance yet to be described. More advanced techniques in systems biology (proteomics, transcriptomics) suggest promising avenues for investigating the disease.

Are catechol-O-methyltransferase gene polymorphisms genetic markers for pain sensitivity after all? - A review and meta-analysis

The catechol-O-methyltransferase (COMT) gene has arguably been the designated pain sensitivity gene for nearly two decades. However, the literature provides inconsistent evidence. We performed several meta-analyses including k = 31 samples and n = 4631 participants thereby revealing small effects of rs4680 on pain thresholds in fibromyalgia, headache and across chronic pain conditions. Moreover, rs4680 effects were found across pain patients when affected, but not unaffected, body sites were assessed. No effect was detected for any other SNP investigated. Importantly, our results corroborate earlier findings in that we found a small effect of COMT haplotypes on pain sensitivity. Our review and meta-analysis contribute to the understanding of COMT-dependent effects on pain perception, provide insights into research issues and offer future directions. The results support the theory that rs4680 might only impact behavioural measures of pain when descending pain modulatory pathways are sufficiently challenged. After all, COMT polymorphisms are genetic markers of pain sensitivity, albeit with some limitations which are discussed with respect to their implications for research and clinical significance.

Innate Immune and Neuronal Genetic Markers are Highly Predictive of Postoperative Pain and Morphine Patient-Controlled Analgesia requirements in Indian but not Chinese or Malay hysterectomy patients

OBJECTIVE

Pain severity and opioid requirements in the postoperative period show substantial and clinically significant inter-patient variation due mainly to factors such as age, surgery type and duration. Genetic factors have not been adequately assessed except for the neuronal OPRM1 rs1799971 and COMT rs4680, whereas the contribution of innate immune signalling pathway genetics was seldom investigated.

SETTING

Hospital surgical ward.

SUBJECTS

107 Indian, 184 Malay and 750 Han Chinese women undergoing total hysterectomy surgery.

METHODS

Morphine consumption, pre- and post-operative pain were evaluated in relation to genetic variability comprising 19 SNPs in 14 genes involved in glial activation, inflammatory signalling and neuronal regulation plus OPRM1 (1 SNP) and COMT (3 SNPs).

RESULTS

Pre- and post-operative 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 when not 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 non-genetic factors and, consider ethnicity-dependent and non-additive genotypic models, when assessing factors that contribute to variability in opioid use.

OPRM1 and COMT polymorphisms: implications on postoperative acute, chronic and experimental pain after cardiac surgery

Aim: Investigate the potential role of OPRM1 (mu-opioid receptor) and COMT (catechol-O-methyltransferase enzyme) polymorphisms in postoperative acute, chronic and experimental thermal pain. Methods: A secondary analysis of 125 adult cardiac surgery patients that were randomized between fentanyl and remifentanil during surgery and genotyped. Results: Patients in the fentanyl group with the COMT high-pain sensitivity haplotype required less postoperative morphine compared with the average-pain sensitivity haplotype (19.4 [16.5; 23.0] vs 34.6 [26.2; 41.4]; p = 0.00768), but not to the low-pain sensitivity group (30.1 [19.1; 37.7]; p = 0.13). No association was found between COMT haplotype and other pain outcomes or OPRM1 polymorphisms and the different pain modalities. Conclusion: COMT haplotype appears to explain part of the variability in acute postoperative pain in adult cardiac surgery patients.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

Our results showed that SCN9A polymorphisms could play a role in acute pain perception and the susceptibility to chronic pain.

Single nucleotide polymorphisms associated with postoperative inadequate analgesia after single-port VATS in Chinese population

Background

Postoperative inadequate analgesia following video-assisted thoracoscopic surgery (VATS) is a common and significant clinical problem. While genetic polymorphisms may play role in the variability of postoperative analgesia effect, few studies have evaluated the associations between genetic mutations and inadequate analgesia after single-port VATS.

Methods

Twenty-eight single nucleotide polymorphisms (SNPs) among 18 selected genes involved in pain perception and modulation were genotyped in 198 Chinese patients undergoing single-port VATS. The primary outcome was the occurrence of inadequate analgesia in the first night and morning after surgery which was defined by a comprehensive postoperative evaluation. Multivariable logistic regression analyses were used to identify the association between genetic variations and postoperative inadequate analgesia.

Results

The prevalence of postoperative inadequate analgesia was 45.5% in the present study. After controlling for age and education level, association with inadequate analgesia was observed in four SNPs among three genes encoding voltage-gated sodium channels. Patients with the minor allele of rs33985936 (SCN11A), rs6795970 (SCN10A), and 3312G > T (SCN9A) have an increased risk of suffering from inadequate analgesia. While the patients carrying the minor allele of rs11709492 (SCN11A) have lower risk experiencing inadequate analgesia.

Conclusions

We identified that SNPs in SCN9A, SCN10A, and SCN11A play a role in the postoperative inadequate analgesia after single-port VATS. Although future larger and long-term follow up studies are warranted to confirm our findings, the results of the current study may be utilized as predictors for forecasting postoperative analgesic effect for patients receiving this type of surgery.

Trial registration

This study was retrospectively registered in the ClinicalTrials.gov Registry (NCT03916120) on April 16, 2019.

The Influence of Race, Ethnicity and Genetic Variants on Postoperative Pain Intensity: An Integrative Literature Review

OBJECTIVES

Chronic postsurgical pain is pain that develops and persists for at least 3 months after a surgical procedure. The purpose of this review was to discover what evidence exists regarding the influence of race and ethnicity on postoperative pain intensity and what evidence exists regarding the influence of genetic polymorphisms on postoperative pain intensity.

DESIGN

Integrative literature review.

DATA SOURCES

CINAHL, PsychInfo, SCOPUS, and PubMed/Medline databases were searched for entries within the last 10 years. Sources included primary research investigating the relationship among race, ethnicity, and genetics in postoperative pain outcomes.

REVIEW/ANALYSIS METHODS

Studies adhered to a strict inclusion and exclusion criteria. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were utilized to evaluate and assess manuscripts for inclusion.

RESULTS

Twelve manuscripts were included for final review. There are significantly higher preoperative and postoperative pain intensity scores reported between African American and Hispanic individuals compared with non-Hispanic whites. Although some studies identified that non-Hispanic whites consumed more opioids and reported increased pain, there were no significant differences in opioid requirements in Hispanic and non-Hispanic individuals. COMT and OPRM1 were the most identified genetic polymorphisms associated with postoperative pain intensity.

CONCLUSIONS

The literature varies with respect to race, ethnicity, and postoperative pain perception. Perioperative pain intensity has been suggested as a significant predictor of chronic postsurgical pain. COMT and OPRM1 may be associated with higher pain perception after surgical procedures.

Candidate gene analyses for acute pain and morphine analgesia after pediatric day surgery: African American versus European Caucasian ancestry and dose prediction limits

Acute pain and opioid analgesia demonstrate inter-individual variability and polygenic influence. In 241 children of African American and 277 of European Caucasian ancestry, we sought to replicate select candidate gene associations with morphine dose and postoperative pain and then to estimate dose prediction limits. Twenty-seven single-nucleotide polymorphisms (SNPs) from nine genes (ABCB1, ARRB2, COMT, DRD2, KCNJ6, MC1R, OPRD1, OPRM1, and UGT2B7) met selection criteria and were analyzed along with TAOK3. Few associations replicated: morphine dose (mcg/kg) in African American children and ABCB1 rs1045642 (A allele, β = -9.30, 95% CI: -17.25 to -1.35, p = 0.02) and OPRM1 rs1799971 (G allele, β = 23.19, 95% CI: 3.27-43.11, p = 0.02); KCNJ6 rs2211843 and high pain in African American subjects (T allele, OR 2.08, 95% CI: 1.17-3.71, p = 0.01) and in congruent European Caucasian pain phenotypes; and COMT rs740603 for high pain in European Caucasian subjects (A allele, OR: 0.69, 95% CI: 0.48-0.99, p = 0.046). With age, body mass index, and physical status as covariates, simple top SNP candidate gene models could explain theoretical maximums of 24.2% (European Caucasian) and 14.6% (African American) of morphine dose variances.

Endogenous Opiates and Behavior: 2016

This paper is the thirty-ninth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2016 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

Ethnicity-dependent influence of innate immune genetic markers on morphine PCA requirements and adverse effects in postoperative pain

Although several genetic factors have been associated with postsurgical morphine requirements, those involving the innate immune system and cytokines have not been well investigated. The aim of this study was to investigate the contribution of genetic variability in innate immune signalling pathways to variability in morphine dosage after elective caesarean section under spinal anaesthesia in 133 Indian, 230 Malay, and 598 Han Chinese women previously studied. Twenty single nucleotide polymorphisms in 14 genes involved in glial activation (TLR2, TLR4, MYD88, MD2), inflammatory signalling (IL2, IL6, IL10, IL1B, IL6R, TNFA, TGFB1, CRP, CASP1), and neuronal regulation (BDNF) were newly investigated, in addition to OPRM1, COMT, and ABCB1 genetic variability identified previously. Postsurgical patient-controlled analgesia morphine use (mg/24 hours) was binned into 6 normally distributed groups and scored 0 to 5 to facilitate step-down multiple linear regression analysis of genetic predictors, controlling for ethnicity and nongenetic variables. Ethnicity, OPRM1 rs1799971 (increased), TLR2 rs3804100 (decreased), and an interaction between ethnicity and IL1B rs1143634 (increased), predicted 9.8% of variability in morphine use scores in the entire cohort. In the Indian cohort, 14.5% of the variance in morphine use score was explained by IL1B rs1143634 (increased) and TGFB1 rs1800469 (decreased). In Chinese patients, the incidence of postsurgical pain was significantly higher in variant COMT rs4680 genotypes (P = 0.0007) but not in the Malay or Indian cohorts. Innate immune genetics may contribute to variability in postsurgical opioid requirements in an ethnicity-dependent manner.

Preoperative Norepinephrine Levels in Cerebrospinal Fluid and Plasma Correlate With Pain Intensity After Pediatric Spine Surgery

PURPOSE

Catecholamines were found to be involved in descending pain modulation and associated with perioperative pain. The purpose of the present study was to investigate the relationship between preoperative concentrations of catecholamines and postoperative pain intensity of pediatric patients.

METHODS

Fifty adolescents with idiopathic scoliosis scheduled for elective spinal fusion surgery were enrolled in this prospective cohort study. Preoperative plasma and cerebrospinal fluid (CSF) samples were collected and analyzed by mass spectrometry. Pain intensity was assessed during the acute postoperative period and in the intermediate period.

RESULTS

Preoperative plasma concentrations of norepinephrine (NE) and normetanephrine (NME), as well as the CSF concentration of NE, were significantly correlated with the presence of pain six weeks after surgery (r = 0.48, 0.50, and 0.50, respectively; p < .002). We also found that preoperative NE levels in CSF were significantly higher in patients reporting moderate to severe pain intensity than in patients with mild pain during the first day following surgery (0.268 ± 0.29 ng/mL vs. 0.121 ± 0.074 ng/mL, p = .01), as well as between patients reporting pain and painless patients at 6 weeks postsurgery (0.274 ± 0.282 ng/mL vs. 0.103 ± 0.046 ng/mL respectively, U = 69.5, p = .002).

CONCLUSIONS

These results support the potential role of catecholamine levels in predicting postoperative pain intensity.

Opioid treatment failure in cancer patients: the role of clinical and genetic factors

AIM

To identify clinical and genetic factors associated with outcome of opioid treatment.

PATIENTS & METHODS

We performed an exploratory analysis in a cohort of 353 patients treated with fentanyl, morphine, oxycodone and/or hydromorphone for cancer-related pain, exploring selected clinical and pharmacogenetic factors for a correlation with treatment failure for all and per type of opioid.

RESULTS

Use of adjuvant pain medication, intensity of pain at rest and age were associated with treatment failure in the various cohorts. Only the genetic variants rs12948783 (RHBDF2) and rs7016778 (OPRK1) correlated statistically significant in univariate, but not in multivariable analysis.

CONCLUSION

Several clinical and genetic factors were identified that warrant further study to clarify their role and use in opioid treatment.

Alternative Splicing of G Protein-Coupled Receptors: Relevance to Pain Management

Drugs that target G protein-coupled receptors (GPCRs) represent the primary treatment strategy for patients with acute and chronic pain; however, there is substantial individual variability in both the efficacy and adverse effects associated with these drugs. Variability in drug responses is due, in part, to individuals' diversity in alternative splicing of pain-relevant GPCRs. G protein-coupled receptor alternative splice variants often exhibit distinct tissue distribution patterns, drug-binding properties, and signaling characteristics that may impact disease pathology as well as the extent and direction of analgesic effects. We review the importance of GPCRs and their known splice variants to the management of pain.