For a study, researchers sought to identify meaningful within-patient change (MWPC) in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).

Data from three phase III clinical studies of tanezumab were examined individually. Tanezumab is a new medication injected subcutaneously every 8 weeks to improve signs and symptoms of moderate-to-severe osteoarthritis (OA). At regular intervals, patients with moderate-to-severe OA of the hip or knee completed the WOMAC and the patient global assessment of OA (PGA-OA). To develop MWPC for WOMAC domains, a repeated measures longitudinal model with change in WOMAC Pain, Physical Function, or Stiffness domain score as the outcome and change in PGA-OA as the anchor was utilized.

About 688, 844, and 2,948 participants were available for analysis in the three investigations, respectively. The analysis revealed and justified a linear link between changes in WOMAC domains and changes in PGA-OA. Furthermore, the connections between these alterations were identical in two trials and closed in the third. Depending on the research and domain, the estimated MWPC for the three WOMAC domains ranged from 0.84-1.16 (0-10 numerical rating scale) and from 12.50-16.23%, corresponding to a 1-category shift on PGA-OA. For a two-category shift, the results ranged from 1.68 to 2.31% and from 25.01 to 32.46%, respectively.

These findings defined MWPCs for WOMAC domains at the individual patient level in individuals with moderate-to-severe hip or knee OA.

Reference: jrheum.org/content/49/6/615