Hemophilia without prophylaxis: Assessment of joint range of motion and factor activity

BACKGROUND: Recurrent joint bleeding in hemophilia results in arthropathy and functional impairment. The relationship of arthropathy development and factor activity (FA) has not been reported in patients with FA levels <15%‐20%. METHODS: During the Centers for Disease Control and Prevention Universal Data Collection, joint range‐of‐motion (ROM) measurements were taken at each comprehensive visit. Data were extracted from male patients with hemophilia (PWH) age ≥2 years with baseline factor activity levels ≤40%, excluding those prescribed prophylaxis, and used to calculate a proportion of normal ROM (PN‐ROM) measure. Data were analyzed using regression models. RESULTS: There were 6703 eligible PWH with 30 102 visits. PN‐ROM declined with increasing age, and was associated with hemophilia severity, race/ethnicity, obesity, and viral illnesses. PWH ≥30 years old with fFA ≤2% and those ≥50 years old with FA ≤5% had mean PN‐ROM values >10% less than controls; those ≥40 years old with FA <1% had values >20% less than controls. In the multivariable analysis, subjects with <1% FA had a 0.43% greater decrease (−0.49 to −0.37, 95% confidence interval) in PN‐ROM each year relative to those with 16%‐40% factor activity. A less pronounced effect was seen with 1%‐5% or 6%‐9% FA. CONCLUSION: The effect of FA on ROM loss is far greater than that of any of the other characteristics, especially with FA <10%. This emphasizes the need to maintain a high index of suspicion for arthropathy in individuals with moderate and low‐mild hemophilia.