We developed and validated a set of composite scores that combine quantitative magnetic resonance (MR)-based measurements of hyaline cartilage damage, bone marrow lesions (BMLs), and effusion-synovitis into composite scores.
We selected 300 participants (development cohort=100, validation cohort=200) from the Osteoarthritis Initiative with complete clinical, radiographic, and MR data at baseline and 24 months. We used semi-automated programs to quantify tibiofemoral and patellar cartilage damage, BML volume, and whole-knee effusion-synovitis volume. The candidate composite scores were formed by summing changes from baseline to 24 months based on pre-specified methods. We evaluated the candidate composite scores 1) ability to differentiate groups with and without KOA progression (17 radiographic and patient-reported definitions), 2) sensitivity to change (standardized response means), and 3) relative performance relating to legacy outcome measures of KOA progression.
Three out of 13 developed composite scores qualified for testing in the validation cohort (ranked by sensitivity to change): 1) whole-knee cumulative cartilage damage, 2) unweighted total knee score, and 3) BML+effusion-synovitis volume. Change in cumulative cartilage damage associated with radiographic progression (Kellgren-Lawrence: OR=1.84; Joint Space Width Progression: OR=2.11). Changes in the unweighted total knee score (OR=1.97) and BML+effusion-synovitis score (OR=1.92) associated with WOMAC knee pain progression CONCLUSION: Two composite scores emerged, reflecting discrete domains of KOA progression. First, cumulative damage, which is measured by a whole-knee cartilage damage score, reflects the damage accrued over time. Second, dynamic disease activity, which is measured by a BML+effusion-synovitis score, relates with changes in a patient’s state of disease and symptoms.

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