Osteoarthritis Patients Show Increased Pain Sensitivity

Increased pain sensitivity linked to higher levels of C-reactive protein and interleukin-6

THURSDAY, March 31 (HealthDay News) -- Patients suffering from osteoarthritis (OA) are more sensitive to experimental pain at multiple body sites compared to healthy controls, according to a study published in the March issue of Arthritis Care & Research.

Yvonne C. Lee, M.D., from the Brigham and Women's Hospital in Boston, and colleagues studied 26 OA patients and 33 age- and sex-matched controls to evaluate the nature of the association between pain and inflammation in OA. Patients underwent psychophysical pain testing to evaluate their sensitivity to temperature and mechanical stimuli. Blood samples taken from the patients at baseline and four times after testing were used to assess the effect of acute pain on C-reactive protein (CRP), interleukin-6 (IL-6), IL-1β, and tumor necrosis factor α levels.

The researchers found that the OA patients had significantly lower pressure pain thresholds and higher heat pain ratings across multiple body sites compared with control subjects. A significantly higher CRP level was seen in OA patients than in the controls, although the CRP level was not affected by pain. OA patient had higher IL-6 levels than did the control patients, although the difference was not statistically significant. IL-6 levels increased in OA patients and controls after pain testing. In patients with OA, heightened pain sensitivity was linked to increased CRP and IL-6 levels.

"Compared with controls, OA patients are more sensitive to pressure stimuli at multiple sites, suggesting defects in central pain processing," the authors write.

One of the study authors disclosed financial relationships with several pharmaceutical companies.

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