To obtain evidence of content validity and reliability of the Colorado Adult Joint Assessment Scale (CAJAS), a clinician-reported outcome (ClinRO) measure, as adapted for use in a population of adults with moderate to severe hemophilia A treated with coagulation factor VIII (FVIII) therapy as secondary prophylaxis or episodic treatment.

Inclusion Criteria:

• Male, 18 to 50 years of age
• Diagnosis of moderate to severe hemophilia A (documented <1-2% Factor VIII Concentration [FVIII:C])
• Willing to maintain current FVIII treatment regimen, whether prophylactic or on-demand, for the duration of the study

Exclusion Criteria:

• Routine need for wheelchair or routine need for two canes or crutches
• Diagnosis of another bleeding disorder such as von Willebrand Disease
• Known event that would interfere with the scheduled CAJAS evaluations (e.g., elective joint surgery, vacation)