RESISTANCE TO ACTIVATED PROTEIN-C, ASSOCIATED WITH ORAL-CONTRACEPTIVES USE EFFECT OF FORMULATIONS, DURATION OF ASSUMPTION, AND DOSES OF OESTRO-PROGESTINS

Resistance to activated protein C (APC-R) is at present considered the most frequent laboratory abnormality in patients with deep vein throm bosis. An increased risk for venous thrombosis is associated with the use of oral contraceptives (OCs). We recently described a statisticall y sig nificant association between APC-R status and oral contraceptive s use in a healthy group of women. We re-evaluated 50 healthy women ta king low-dose combination OCs in order to consider a possible correlat ion. between the APC sensitivity ratio (APC-SR) and different oral con traceptive formulations. Seven women showed an APC ratio less than or equal to 2 (APC-resistant). Only one of the seven women was found to b e heterozygous for Leiden factor V mutation. We observed no significan t differences between normally sensitive and APC-resistant women in te rms of duration of OC use, amount of estrogenic or progestogenic dose, or type of formulation. We conclude that APC-resistance associated wi th oral contraceptives use seems to occur only in predisposed subjects (in our results, about 12% of the healthy population). (C) 1996 Elsev ier Science Inc.