The contribution of pain to disability in experimentally induced arthritis.

We examined the differential effects of disease severity and pain on morbidity (as measured by weight loss and decrease in activity) in rats with adjuvant-induced arthritis. We found that eliminating nociceptive messages from affected extremities, although not significantly affecting the course of the disease, attenuated the morbidity observed in arthritic rats. When pain was factored out, the severity of the arthritis had no significant effect on the same measures of morbidity. These findings suggest that treatment of pain may reduce morbidity, and thereby may have significant benefits beyond that provided by slowing of the disease process.