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.