Non-inflammatory Causes of Pain in Patients with Rheumatoid Arthritis.

Although pain in rheumatoid arthritis (RA) is frequently thought to be inflammatory in nature, the association between measures of inflammation and pain intensity is low. This observation is likely due to the multifactorial nature of pain. In addition to pain from joint inflammation, RA patients may also have pain due to structural damage or central etiologies, such as aberrancies in the central nervous system (CNS) pain regulatory pathways. These CNS pathways include mechanisms that facilitate pain, as well as mechanisms that inhibit pain. Other factors, such as sleep disturbances, depression, anxiety, and catastrophizing, may also impact the perception of pain in RA patients. Since pain is frequently used as a proxy for inflammation in the assessment of RA disease activity, it is important that patients and physicians recognize that not all pain is inflammatory, and alternative management strategies, other than escalating disease-modifying antirheumatic drug treatment, may need to be considered.