Peripheral and Central Sensitization of Pain in Individuals With Hand Osteoarthritis and Associations With Self-Reported Pain Severity.

OBJECTIVE: Pain sensitization, an important osteoarthritis (OA) pain mechanism, has not been substantially investigated in patients with hand OA. It is unknown how peripheral and central sensitization are related to self-reported hand pain.

METHODS: Individuals with verified hand OA in the Nor-Hand study underwent quantitative sensory testing of pressure pain thresholds (PPTs) locally (painful and nonpainful finger joints) and remotely (wrist, trapezius, and tibialis anterior muscles), and testing of temporal summation (TS), a manifestation of central sensitization. We examined cross-sectional associations of PPT tertiles and TS with hand pain using the Numerical Rating Scale (NRS) (range 0-10) and the Australian/Canadian Osteoarthritis Hand Index (AUSCAN) pain subscale (range 0-20). Linear regression models were adjusted for demographics, psychosocial factors, and radiographic severity.

RESULTS: This study included 282 participants (88% female) with a median age of 61 years (interquartile range [IQR] 57-66). Participants with the lowest PPTs in their finger joints and in most remote locations reported higher NRS pain values, compared to patients with the highest PPTs, with adjusted β values ranging from 0.6 (95% confidence interval [95% CI] 0.0, 1.2) to 0.9 (95% CI 0.3, 1.5). The 118 participants (42%) with TS reported higher mean ± SD NRS pain values compared to those without TS (4.1 ± 2.4 versus 3.1 ± 1.7; adjusted β = 0.6 [95% CI 0.2, 1.1]). Neither PPTs nor the presence of TS were associated with AUSCAN pain.

CONCLUSION: Central sensitization was common in patients with hand OA. Lower local and widespread PPTs and the presence of TS were associated with higher hand pain intensity, even after adjustment for demographics, psychosocial factors, and radiographic severity. Sensitization may therefore represent a possible treatment target.