Self-reported painful joint count and assessor-reported tender joint count as instruments to assess pain in hand osteoarthritis

OBJECTIVES: To evaluate self-reported and assessor-reported joint counts for pain and their value in measuring pain and joint activity in hand OA patients. METHODS: A total of 524 patients marked painful joints on hand diagrams. Nurses assessed tenderness upon palpation. Pain was measured with a visual analogue scale pain and the Australian/Canadian hand OA index subscale pain. Synovitis and bone marrow lesions in right hand distal/proximal interphalangeal joints on MRI served as measure of joint activity. Agreement was assessed on the patient (intraclass correlation coefficient, Bland–Altman plot) and joint level (percentage absolute agreement). Correlations with measures of pain and joint activity were analysed, and joint level associations with synovitis/bone marrow lesions were calculated. RESULTS: Self-reported painful joint count (median 8, interquartile range 4–13) was consistently higher than assessor-reported tender joint count (3, 1–7). Agreement between patients and nurses on overall scores was low. Percentage absolute agreement on the joint level was 61–89%. Joint counts correlated similarly but weakly with measures of pain and joint activity (r = 0.14–0.38). On the joint level, assessor-reported tenderness was more strongly associated with synovitis/bone marrow lesions than self-reported pain. CONCLUSION: In hand OA, self- and assessor-reported joint counts cannot be used interchangeably, and measure other pain aspects than questionnaires. Assessor-reported tenderness was most closely related to MRI-defined joint activity.