Association of COMT gene variability with pain intensity in patients after total hip replacement.

Pain is one of the most interdisciplinary clinical symptoms of a disease. The aim of the study was to evaluate the association of COMT gene polymorphism with pain perception in patients after total hip replacement (THR). The study included 195 patients qualified for surgical treatment (THR) due to osteoarthritis. Patients previously undergoing hip replacement subsequently underwent multimodal pain management therapy, in accordance with the recommendations for treating postoperative pain. The intensity of pain was measured three times at pre-defined time intervals: 1.5, 6 and 12 months after hip replacement, using the visual analogue scale. Single nucleotide polymorphism (SNP) in the COMT gene rs4680: A>G (Val158Met), rs6269: A>G (promoter region), rs4633: C>T (His62His) and rs4818: C>G (Leu136Leu) was genotyped. COMT SNP frequency distribution was analysed. For rs6269 and rs4818, the minor allele was the G allele (38.7 and 38.5%, respectively). It was also observed that rs4633 (T) allele frequency (50%) equalled that of the rs4680 (A) allele (50%). We assessed COMT haplotype frequency in the patients studied. The most frequent haplotype was haplotype M (ATCA) (50%), the rarest haplotype was haplotype R (ATGG), with a frequency of 0.3%. The most frequent diplotype was H/M, which was found in 37.95% of the patients. The frequency of other diplotypes was: M/M-24.10%, H/H-15.90% and L/M-13.33%. The study showed a significant association of rs4818 G allele and equivalent COMT H haplotype with lower sensitivity to pain after hip replacement.