The inverse OARSI-OMERACT criteria is a valid indicator of the clinical worsening of knee osteoarthritis: data from the Osteoarthritis Initiative
Abstract
Objective We assessed if the inverse OARSI-OMERACT criteria relate to concurrent radiographic knee osteoarthritis (KOA) progression and decline in walking speed as well as future knee replacement.
Methods We conducted knee-based analyses of data from the Osteoarthritis Initiative. All knees had symptomatic osteoarthritis: at least doubtful radiographic KOA (Kellgren-Lawrence Grade≥1) and knee pain≥10/100 (WOMAC pain) at the 12-month visit. The inverse of the OARSI-OMERACT responder criteria depended on knee pain and function, and global assessment of knee impact. We used generalized linear mixed models to assess the relationship of the inverse OARSI-OMERACT criteria over 2 years (i.e.,12 and 36-month visits) with worsening radiographic severity (any increase in Kellgren-Lawrence Grade from 12- to 36-months) and decline in self-selected 20-m walking speed of >0.1m/s (from 12- to 36-months). We used a Cox model to assess time to knee replacement during the 6 years after the 36-month visit as an outcome.
Results Among the 1,746 analyzed, 19% met the inverse OARSI-OMERACT criteria. Meeting the inverse OARSI-OMERACT criteria was associated with almost double the odds of experiencing concurrent worsening in radiographic KOA severity (odds ratio [OR]=1.89 (95% confidence interval [CI]=1.32 to 2.70)) or decline in walking speed (OR=1.82 (95%CI=1.37 to 2.40)). A knee meeting the inverse OARSI-OMERACT criteria was more likely to receive a knee replacement after the 36-month visit (23%) compared with a non-responder (10%; hazard ratio=2.54, 95%CI=1.89 to 3.41).
Conclusion The inverse OARSI-OMERACT criteria for worsening among people with KOA had good construct validity in relation to clinically relevant outcomes.