An Analysis of the Neuropathic Pain Components in Rheumatoid Arthritis Patients

Objective To analyze the neuropathic pain (NeP) components in patients with rheumatoid arthritis (RA). Methods The painDETECT questionnaire (PD-Q) was completed by 300 RA patients (79 men, 221 women). Results Nine patients (3.0%) were categorized as likely NeP, 33 (11.0%) were categorized as possible NeP, and 258 (86.0%) were categorized as unlikely NeP. When we excluded patients with diabetes mellitus, spinal diseases, neurological diseases, and herpes zoster infection (conditions associated with NeP), 5 of the patients (1.7%) had likely NeP, and 23 (7.7%) had possible NeP without any underlying conditions. Furthermore, there were no marked differences in the percentages of these underlying conditions among the patients with likely, possible, and unlikely NeP. When we compared patients with likely and possible NeP (n=42) and unlikely NeP (n=258), the body mass index (BMI), disease activity score-28 based on the erythrocyte sedimentation rate, C-reactive protein level, pain visual analogue scale (VAS), and PD-Q score were significantly higher in the patients with likely and possible NeP than in those with unlikely NeP. A multivariate analysis showed that BMI ≥22 and not being in clinical remission were associated with NeP. Conclusion Although RA pain has usually been classified as nociceptive pain, the present study clarified that a significant number of patients might have NeP. The present findings suggest that high disease activity and being overweight are related to NeP in RA patients.