Do Preoperative Psychological Condition and μ1-opioid Receptor Gene Polymorphism 118a>G Affect Opioid Analgesia Efficacy After Major Urological Surgeries?

Abstract

Background. Effective postoperative analgesia remains an essential problem in modern anesthesiology. The search of factors affecting the pain intensity after the surgery is of significant practical importance. It is known, that personal experience, psychological and social state may be related to the level of postoperative pain syndrome. At the same time, genetic factors regulating opioid pharmacodynamics contribute to the large interpatient variability in postoperative opioid requirements. Thus, OPRM1 gene polymorphism 118A>G is a primary candidate for genetic influence on the efficacy of opioids, as well as patients emotional reactions. The aim of this study is to evaluate the interrelation between patients preoperative psychological condition, variations of the OPRM1 gene and pain intensity after the surgery. Materials and Methods. The observational study has been conducted, which included 100 consecutive patients undergoing major urological surgeries with lumbotomic access. Postoperative pain management included intramascular administration of trimeperidine and NSAIDs on doctor's prescription. The level of preoperative anxiety and depression was assessed using the HADS scale (Hospital Anxiety and Depression Scale). Pain after the surgery was assessed within the first 24 hours after the surgery. SNP OPRM1 118A>G was analysed using real-time PCR. Differences in patient groups were considered statistically significant at p<0.05. Results. Clinical anxiety was revealed in 24% patients, clinical depression - in 18%. In the group of patients with clinical anxiety the maximal level of pain on the first day after the surgery was 9 (7-10) points, 8 (5-9) points in the group of subclinical anxiety, and 5 (4-8) points in the group with no anxiety symptoms (p < 0.001). Significant differences in the following parameters were also observed between groups: duration of maximal pain syndrome within the first postoperative day and the extent of pain interference with moving in bed, deep breathing and sleeping. Moreover, significant differences in the all of studied parameters have been revealed in the group of patients depending on the level of depressive disorders. The relationship between SNP OPRM1 118A>G and patients preoperative psychological status has been identified: the preoperative anxiety and depression scores in the group of AG+GG carriers were 45.4-72.7% higher than in AA genotype carriers. Conclusions. Preoperative psychological state affects the pain intensity after the surgery. The potential role of SNP OPRM1 118A>G in the molecular mechanisms of affective disorders and modulation of pain perception has been revealed. In order to improve the effectiveness of postoperative pain management, it is advisable to continue the search of interrelationship between these parameters.