Inflammation and sleep problems are associated with increased pain in rheumatoid arthritis (RA) patients, a new study has found.
Researchers from the Division of Rheumatology and Pain Management Center of Brigham and Women's Hospital, and the Chronic Pain and Fatigue Center of the University of Michigan Medical School, claim that while inflammation is linked to heightened pain sensitivity at joint sites, increased sleep problems are associated with heightened pain sensitivity at both joint and non-joint sites.
They assessed experimental pain sensitivity, disease activity, sleep problems and psychiatric distress in 59 women with RA, to reach the conclusion.
Questionnaires were filled to note women's sleep problems and psychiatric distress and measure the levels of C-reactive protein as an indicator of disease activity.
It also recorded pain sensitivity with pressure pain threshold testing at joint and non-joint sites. Lower pain thresholds are indicative of higher pain sensitivity.
The authors of the study published in BioMed Central's open access journal, 'Arthritis Research and Therapy' said: "Sleep problems were inversely associated with pain threshold at all sites, suggesting a defect in central pain processing."
The result now urges researchers to look into the mechanisms underlying sleep disorders and pain in RA patients, particularly given the common occurrence of sleeping problems among these patients.
Nearly 1 percent of the population suffers from the autoimmune disease, causing chronic inflammation.
In fact sufferers often report ongoing pain in spite of successful anti-inflammatory treatment.
Lead author Yvonne Lee said: "Since differences in pain sensitivity may shape the course of pain complaints and influence treatment decisions, it is important to understand the factors associated with enhanced pain sensitivity.
"Physicians and researchers should consider both inflammatory and non-inflammatory factors when evaluating pain in research settings and in the clinic."