Objective: This study assessed the utility and construct validity of a new patient global assessment of symptom change for hand osteoarthritis (OA) by examining its associations with change over time in grip strength, pinch strength, and AUStralian CANadian Osteoarthritis Hand Index (AUSCAN).
Methods: Participants (N=531, 80% female, mean age=68) were part of a study on the Genetics of Generalized Osteoarthritis (GOGO) and completed two assessments (average 4 years apart). At the second assessment, participants described change in their right and left hand pain, aching, and stiffness on a 15-point scale with descriptors ranging from "Great deal worse" to "Great deal better". Linear regression models examined associations of global change scores with changes in hand strength and AUSCAN, controlling for age, gender, number of hand joints with OA, and time between assessments.
Results: Both right and left hand global assessment of change scores were significantly associated with change in AUSCAN, grip strength, and right hand pinch strength (P<0.05), and approached significance for left hand pinch strength (P=0.06). The strongest associations were between global change scores and AUSCAN change (right hand: beta=0.29, P<0.001; left hand: beta=0.27, P<0.001). Associations of change scores with grip and pinch strength were stronger among participants with greater radiographic OA severity at baseline.
Conclusion: Results support the validity of this new global assessment of symptom change. This measure is particularly useful for assessing change over time when no baseline data are available. Additional research should examine this measure's responsiveness in the context of clinical trials.