Activated proten C. resistance in contraceptive pill users with deep vein thrombosis: relation to other risk factors and pill type

ABSTRACT

The relative risk and mechanism of thrombosis induced by different preparations of oral contraceptives is a mater of debate. The phenomenon of activated protein C [APC] resistance was recently described as a possible mechanism for thrombosis in hypercoagulable states. We investigated the prevalence of APC resistance, using an APC-[DVT] on oral contraceptive pills [group I]. Also included were 30 age matched women on oral contraceptives without evidence of DVT [group II] and 20 healthy control subjects of comparable age who never used oral contraceptives [group III]. Our results showed a significant increase in the percentage of APC-resistance positive cases among contraceptive Pill users with DVT [Group I] compared to pill users without DVT [group II] and the control [group III] [26.67% vs 6.67 and 5% respectively]. Among other risk factors positive family history [F.H.] of thrombosis and body mass index [BMI] were significantly higher in group I compared to groups II and III [30% vs 6.7% respectively for F.H. of thrombosis] and 39.21 +/- 6.09 vs 30.33 +/- 6.60 and 31.42 +/- 5.04 respectively for BMI]. APC-SR correlated negatively with BMI but did not correlate with age, serum cholesterol, serum triglycerides, duration of contraceptive use and platelet count. Users of second generation contraceptives had a higher incidence of DVT compared to users of third generation contraceptives with lower oestrogen concentration [56.41% vs 38.09% respectively] but APC-SR was not significantly different in the two groups [2.09 +/- 0.56 vs 2.70+/= 0.18 respectively]. We conclude that APC-resistance is more frequent in contraceptive pill users with thrombosis complications. Other risk factors include positive F.H. of thrombosis and higher BMI. The risk of thrombosis is higher among users of second generation cattraceptives. It is justified to screen women for APC resistance before prescribing oral contraceptives specially when obese or with positive family history of thrombosis