What is the correlation between factor VIII levels and bleeding in carriers of hemophilia A?¶
Answer: The Canadian Hemophilia Carriers (CHiC) study evaluated the determinants of FVIII/FIX levels, bleeding score, and health-related quality of life in 92 hemophilia A carriers. Key findings:
- More bleeding with lower factor: the Self-BAT bleeding score correlated inversely with FVIII:C (rs = −0.298, 95% CI −0.482 to −0.09).
- VWF is a major driver: VWF:Ag correlated with FVIII:C (rs = 0.622, 95% CI 0.47 to 0.737) and with Self-BAT (rs = 0.255, 95% CI 0.043 to 0.445).
- VWF:Ag tracked with category: lower in mild hemophilia A (mean 82.8 IU/dL) than in symptomatic (129.6) or asymptomatic carriers (164.2).
- Blood type: present in 83.3% of mild hemophilia A, 59.1% of symptomatic, and 37.5% of asymptomatic carriers; associated with 29.8% lower VWF:Ag, 15.2% lower FVIII:C, and a 1.44-fold higher VWFpp/VWF:Ag.
- Multivariable analysis confirmed the links between FVIII:C and VWF:Ag (B 0.26, 95% CI 0.17 to 0.34), Self-BAT and FVIII:C (B −0.06, 95% CI −0.1 to −0.01), and Self-BAT and ABO (B −2.73, 95% CI −5.41 to −0.04).
- Quality of life: the SF-36v2 Physical Component Summary correlated with Self-BAT (rs = −0.255) and joint health (rs = −0.325); mental health domains were linked with feelings of guilt and burden.
Related: 0012 — hemophilia carriers vs. hemophilia — the nomenclature these carrier categories come from.