Early-stage vs established knee osteoarthritis: A comparative observational study on prevalence and changes in pain, function and quality of life after supervised exercise and education among 10,365 patients.

Objective: Compare prevalence and changes in outcomes among established and early-stage knee osteoarthritis (KOA) patients undertaking supervised exercise and education.

Methods: Patients from Good Life with osteoArthritis in Denmark (GLA:D®) were stratified into three groups: established KOA (ACR/EULAR criteria), early-stage KOA (diagnostic-model-outcome ≥70%, Criteria for the Early Diagnosis of knee Osteoarthritis) or potential early-stage KOA (diagnostic-model-outcome 30-69%). Mixed-effects models and the proportion of patients by group achieving minimal clinically important improvements (MCIIs) were used to investigate changes in VAS pain intensity (0-100mm), Knee injury and Osteoarthritis Outcome Score (KOOS) Quality of Life (QoL; 0-100), 40 m Walk test and 30 s chair-stand test at 3 and 12 months.

Results: Compared to established KOA (61% of 10,365 patients), early-stage KOA (27%) had similar knee pain at baseline (mean (standard deviation); 51 (22) vs 45 (22)), and improvement in pain (mean (95% CI) -15 (-15 to -14) vs -14 (-15 to -13), ≥MCII: 55% vs 54%) and KOOS QoL (≥MCII: 50% vs 50%) at 12 months, and in walking speed (≥MCII: 56% vs 52%) and chair-stands (≥MCII: 55% vs 52%) at 3 months. Compared to either group, potential early-stage KOA (10%) had lower baseline pain (34 (32.7)) and less improvement in pain (-9.8 (-11.3 to -8.2; ≥MCII: 47%)), but comparable improvements in KOOS QoL (≥MCII: 50%), walking speed (≥MCII: 51%) and chair-stands (≥MCII: 51%).

Conclusion: Patients with early-stage KOA achieved comparable improvements at 3 and 12 months to those with established KOA, supporting supervised exercise and education as a viable management strategy for early-stage KOA.