Comparison of Magnetic Resonance Imaging Scales for Assessment of Interval Changes of Arthropathy in Boys with Severe Hemophilia.

Background/Objectives: The variety of magnetic resonance imaging (MRI) scales available to measure soft tissue and osteochondral changes in joints of persons with hemophilia poses challenges in evaluating published clinical/research studies. To evaluate the value of four MRI scales [(i) the 17-point International Prophylaxis Study Group [IPSG] additive scale; (ii) and (iii) the compatible IPSG progressive (P) and additive (A) scales; and (iv) the Denver progressive scale] to assess joint change in boys with hemophilia participating in a prospective two-year prophylaxis study. Methods: Boys with severe hemophilia A (ages, 7-16 years) followed at the Hospital for Sick Children, Toronto, Canada had MRI evaluations of six index joints (ankles, knees, elbows) at study entry and exit. Musculoskeletal (MSK) outcomes included in the study were the Colorado Child Physical Examination (PE) scale; the Pettersson (X-ray) scale; and the aforementioned 4 MRI scales. Results: Very strong (r ≥ 0.80) correlations were observed between the IPSG 17-point, the IPSG progressive (P) and the Denver MRI scales, and moderate (r = 0.40-0.59) to strong (r = 0.60-0.79) correlations for the IPSG 17 point and the IPSG additive (A) MRI scales. Very weak (r = 0.20-0.39) or no correlations were observed between soft tissue MRI scores and the swelling item of the Child PE scale. Conclusions: All four MRI scales demonstrated relative comparability of their construct validities for assessing mild/moderate hemophilic arthropathy. The 17-point IPSG additive scale is recommended as a reference standard in future long-term studies of young boys with hemophilia receiving factor and non-factor-based preventive therapies.