Pain is a significant burden for rheumatoid arthritis (RA) patients despite advancements in treatment. We examined the independent contribution of pain centralization to the pain experience of patients with active RA.
Two hundred and sixty-three RA patients with active disease underwent quantitative sensory testing (QST) including assessment of extra-articular pressure pain thresholds (PPTs), temporal summation (TS), and conditioned pain modulation (CPM). The pain experience was assessed by a pain intensity numeric rating scale and the Patient-Reported Outcomes Measurement Information System (PROMIS® ) Pain Interference computerized adaptive test. We examined associations between QST measures and pain intensity and pain interference. Multiple linear regression models were adjusted for demographic and clinical variables, including swollen joint count and C-reactive protein.
Patients with the lowest PPTs (most central dysregulation) reported higher pain intensity than patients with the highest PPTs (adjusted mean difference (95% CI) 1.02 (0.37, 1.67)). Patients with the highest TS (most central dysregulation) had higher pain intensity than those with the lowest TS (adjusted mean difference (95% CI) 1.19 (0.54, 1.84)). CPM was not associated with differences in pain intensity. PPT and TS were not associated with pain interference. Patients with the lowest CPM (most centrally dysregulated) had lower pain interference than patients with the highest CPM (adjusted mean difference (95% CI) -2.35 (-4.25, -0.44)).
Pain centralization, manifested by low PPTs and high TS, was associated with more intense pain. Clinicians should consider pain centralization as a contributor to pain intensity, independent of inflammation.