Patients tested for APC were more likely to report an improvement in quality of life than those for thrombophilia (OR = 2.97, 95%CI 1.14, 7.72; p = 0.025).
Elevation of plasma FIXa activity in association with reductions in TFPI-α and PS is a potential mechanism for systemic hypercoagulability and resistance to APC in premenopausal females on hormonal contraception.
Impaired interaction of elongated APC molecules with a membrane-surface and/or factor Va which is the physiological substrate for APC, is manifested in vivo by thrombophilia.
Mutated FV (FVR506Q, FV:Q506 or FV Leiden) has normal procoagulant properties but shows partial resistance to APC, which results in a hypercoagulable state conferring a lifelong increased risk of thrombosis.