Correlation of Pain and Disability with Disease Activity in Rheumatoid Arthritis Patients with the Catechol-O-Methyltransferase Val158Met Single Nucleotide Polymorphism

Background and Objectives: Pain perception in rheumatoid arthritis (RA) may be affected by Catechol-O-methyltransferase (COMT) polymorphism, which alters catecholamines-mediated central pain processing. The COMT Val158Met single nucleotide polymorphism (SNP) causes important functional alterations of the COMT enzyme. In this, the Val allele gives rise to an effective enzyme, whereas the Met allele produces a defective enzyme, which cannot clear catecholamines effectively from the system. The objective of this study was to determine the correlation of pain and disability with disease activity in RA patients with different COMT genotypes. Methods: This was a cross-sectional pilot study involving 60 female patients with RA who met the 2010 ACR/EULAR classification criteria. The Numerical Pain Rating Scale (NPRS) and Cochin Hand Function Scale (CHFS) were administered and 3 mL venous blood samples were taken for high-sensitivity C-reactive protein (hs-CRP) estimation and genotyping. Genotyping for the COMT Val158Met allele was performed via the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The erythrocyte sedimentation rate (ESR) was determined as a routine hospital procedure. Results: The odds of developing moderate to severe pain in the Met/Met genotype group were 10.4 times greater than those in the Val/Val genotype group. There was a positive correlation between NPRS and ESR, Disease Activity Score 28 (DAS28)-ESR and CHFS, DAS28-CRP and CHFS, DAS28-ESR and NPRS, DAS28-CRP and NPRS in the Val/Val genotype. In the Val/Met genotype, DAS28-ESR and DAS28-CRP were positively correlated with NPRS. Thus, the COMT Val158Met polymorphism may be a factor which may moderate the relationship of pain and disability with disease activity in RA patients.