Impact of oral contraceptives and smoking on arterial and deep venous thrombosis: A retrospective case control study

Abstract

The scientific debate on oral contraceptives (OCs) therapy and thrombotic diseases continues unabated. This retrospective casecontrol study was intended to evaluate the age specific effects of oral contraceptives and smoking on the risk of deep venous hrombosis, pulmonary thromboembolism and arterial thombosis in women under 50 years. The study included evaluation of registry records of Bulgarian women discharged from the National Heart Hospital, Sofia from 2005 through 2009 after thromboembolic event. The relative risk of thrombotic disease was seen to increase with oral contraceptive use. The risk of arterial disease OR 3.6 (CI1.3-6.8) exceeded those of venous disease OR 2.3 (CI 1.3-4.0). In the 2005-2009 data the relative risk of thrombotic diseases was seen to increase age-dependently. The increase was exponential for arterial thrombosis, and linear for venous thromboembolism. The combination of smoking with oral contraceptives, containing low-dose ethinylestradiol (0.03 mg) and progestins may havesynergistic effects on risks of arterial thromboembolism, and might aggravate venous thrombosis.Most probably different factors that favor vascular narrowing or occlusion might explain the association between deep venous thrombosis, pulmonary thromboembolism, OCs use and smoking. Women, especially older than 35 years, should be assessed for thrombogenic risk factors including smoking, hypertension, methabolic syndrome, and other vascular diseases prior to oral contraceptive use.