Patient acceptable symptom state and treatment failure threshold values for work productivity and activity Impairment and EQ-5D-5L in osteoarthritis

OBJECTIVE: To estimate patient acceptable symptom state (PASS) and treatment failure (TF) threshold values for Work Productivity and Activity Impairment (WPAI) measure and EQ-5D-5L among people with hip or knee osteoarthritis (OA) 3 and 12 months following participation in a digital self-management intervention (Joint Academy®).

METHODS: Among the participants, we computed work and activity impairments scores (both 0-100, with a higher value reflecting higher impairment) and the Swedish hypothetical- (range: - 0.314 to 1) and experience-based (range: 0.243-0.976) EQ-5D-5L index scores (a higher score indicates better health status) at 3- (n = 14,607) and 12-month (n = 2707) follow-ups. Threshold values for PASS and TF were calculated using anchor-based adjusted predictive modeling. We also explored the baseline dependency of threshold values according to pain severity at baseline.

RESULTS: Around 42.0% and 48.3% of the participants rated their current state as acceptable, while 4.2% and 2.8% considered the treatment had failed at 3 and 12 months, respectively. The 3-month PASS/TF thresholds were 16/29 (work impairment), 26/50 (activity impairment), 0.92/0.77 (hypothetical EQ-5D-5L), and 0.87/0.77 (the experience-based EQ-5D-5L). The thresholds at 12 months were generally comparable to those estimated at 3 months. There were baseline dependencies in PASS/TF thresholds with participants with more severe baseline pain considering poorer (more severe) level of WPAI/EQ-5D-5L as satisfactory.

CONCLUSION: PASS and TF threshold values for WPAI and EQ-5D-5L might be useful for meaningful interpretation of these measures among people with OA. The observed baseline dependency of estimated thresholds limits their generalizability and values should be applied with great caution in other settings/populations.