Influences of COMT rs4680 and OPRM1 rs1799971 Polymorphisms on Chronic Postsurgical Pain, Acute Pain and Analgesic Consumption After Elective Caesarean Delivery.

Objectives: The main objectives of this study were to assess the effects of cathechol-O-methyl-transferase (COMT) rs4680 and mu-opioid receptor rs1799971 polymorphisms alone or genotype combinations on chronic postsurgical pain (CPSP), acute pain, and analgesic consumption after elective cesarean delivery in a Chinese cohort. Materials and Methods: Two hundred sixty-six patients undergoing elective cesarean delivery with a Pfannenstiel incision under spinal anesthesia were enrolled in this prospective, observational study. All patients were screened for rs4680 and rs1799971 using a peripheral venous blood sample of DNA. Postoperative pain relief was provided by IV patient-controlled analgesia with sufentanyl and tramadol for 48 hours post-operatively. Postoperative pain scores and analgesic consumption were assessed, and CPSP was evaluated 3 months after surgery in all patients. Results: Twenty-nine patients (29/266; 10.9%) developed CPSP at 3 months after surgery. The risk factors for CPSP included previous cesarean delivery and higher analgesic consumptions at 24 hours and 48 hours postoperatively (P=0.032, 0.015, and 0.008, reapectively). No associations were found between CPSP and a single rs4680 and rs1799971 polymorphism, or their combinations (P>0.05). In contrast, patients with rs1799971 GG required higher patient-controlled analgesics at 24 hours and 48 hours postoperatively compared with those with other genotypes (GG>AG>AA). However, no significant effects of interactions between the 2 single nucleotide polymorphisms on analgesic consumption were observed. Discussion: Our results indicate that cathechol-O-methyl-transferase rs4860 and mu-opioid receptor rs1799971 may not contribute to CPSP development after cesarean delivery. The genotype of rs1799971 affects postcesarean analgesic requirement, while the rs4680 do not. Additional larger studies are needed to confirm these findings.