The responsiveness of joint counts, patient-reported measures and proposed composite scores in hand osteoarthritis: analyses from a placebo-controlled trial.

Objective: To evaluate the responsiveness of joint counts, patient-reported measures and proposed composite scores in hand osteoarthritis (HOA).

Methods: Data were used from a previously reported study in which 83 patients with HOA were randomly assigned to CRx-102 or placebo. CRx-102 consists of prednisolone (3 mg/day) and dipyridamole (400 mg/day), and was shown to be superior to placebo. Assessments were performed at baseline and after 7, 14, 28 and 42 days, and included the Australian/Canadian osteoarthritis hand index (AUSCAN), visual analogue pain subscale (VAS) pain and patient global, and counts of distal interphalangeal (DIP), proximal interphalangeal (PIP), metacarpophalangeal and carpometacarpal (CMC) joints (tenderness, soft tissue swelling, bony enlargement, limited motion). Various combinations of patient-reported outcomes and joint counts were computed as composite scores (similar to clinical disease activity index) and tested for responsiveness. For each measure, mean change from baseline to day 42, treatment effect, standardised response mean (SRM) and relative efficiency compared with AUSCAN pain were calculated.

Results: The SRM were largest for VAS patient global (0.92), VAS pain (0.77) and AUSCAN pain (0.68), whereas the responsiveness of tender (0.46) and swollen joint counts (0.51) (18 joint assessment of DIP, PIP, CMC) was similar to AUSCAN stiffness (0.53) and physical function (0.37). Composite scores showed similar responsiveness as patient-reported pain and global.

Conclusion: Patient-reported pain and patient global assessment were the most responsive outcomes, whereas joint counts had similar responsiveness to patient-reported stiffness and physical function. Composite scores were as responsive as VAS pain, and these results encourage further elaboration and validation of composite scores in HOA in larger studies.