(HealthDay News) – Compared with pain-free control patients, women with rheumatoid arthritis (RA) exhibit impaired conditioned pain modulation (CPM), according to research published online Nov 1 in Arthritis & Rheumatism.
Yvonne C Lee, MD, of Brigham and Women’s Hospital in Boston, and colleagues conducted a study involving 58 women with RA and 54 age-matched pain-free controls to compare CPM, pressure pain threshold, and pressure pain tolerance. CPM was evaluated using a cold water bath, and pain threshold and tolerance were measured using an algometer.
The researchers found that median CPM levels were significantly lower in RA patients compared with control patients. Pain threshold and tolerance was lower at the wrists for patients with RA. In addition, patients with RA displayed significantly greater problems with sleep, catastrophizing, depression, and anxiety compared with controls. Based on mediation analyses, sleep disturbance was found to partially account for low CPM levels.
“In conclusion, RA patients had lower CPM and lower pressure pain threshold and pressure pain tolerance at joint sites compared to pain-free controls. The association between RA and diminished CPM may be mediated by sleep problems,” the authors write. “Future studies are needed to examine whether improving sleep and managing pain catastrophizing may prevent or reverse the development of abnormal pain mechanisms and ultimately improve pain control in RA.”
Several authors disclosed financial ties to the pharmaceutical industry.