Interpretation threshold values for patient-reported outcomes in patients participating in a digitally delivered first-line treatment program for hip or knee osteoarthritis

Abstract

ObjectiveEstablish proportions of patients reporting important improvement, acceptable symptoms and treatment failure and define interpretation threshold values for pain, patient-reported function and quality-of-life after participating in digital first-line treatment including education and exercise for hip and knee osteoarthritis (OA). MethodsObservational study. Responses to the pain Numeric Rating Scale (NRS, 0–10 best to worst), Knee injury and Osteoarthritis Outcome Score 12 (KOOS-12) and Hip disability and Osteoarthritis Outcome Score 12 (HOOS-12, both 0–100 worst to best) were obtained for 4383 (2987) and 2041 (1264) participants with knee (hip) OA at 3 and 12 months post intervention. Threshold values for Minimal Important Change (MIC), Patient Acceptable Symptom State (PASS) and Treatment Failure (TF) were estimated using anchor-based predictive modeling. Results70–85% reported an important improvement in pain, function and quality of life after 3 and 12 months follow-up. 42% (3 months) and 51% (12 months) considered their current state as satisfactory, whereas 2–4% considered treatment failed. MIC values were −1 (NRS) and 0–4 (KOOS/HOOS-12) across follow-ups and joint affected. PASS threshold value for NRS was 3, and 53–73 for the KOOS/HOOS-12 subscales Corresponding values for TF were 5 (NRS) and 34–55 (KOOS/HOOS-12). Patients with more severe pain at baseline had higher MIC scores and accepted poorer outcomes at follow-ups. ConclusionThreshold estimates aid in the interpretation of outcomes after first-line OA interventions assessed with NRS Pain and KOOS/HOOS-12. Baseline pain severity is important to consider when interpreting threshold values after first-line interventions in these patients.