New use of third generation oral contraceptives is associated with a four-fold increased risk of venous thromboembolism compared with users of second generation oral contraceptives, particularly among young, healthy women.
PIP: This article focuses on venous thromboembolism (VTE) cases among oral contraceptive (OC) users. New use of third generation oral contraceptives is associated with a four-fold increased risk of VTE compared with the users of second generation OCs, particularly among young, healthy women. Data were obtained from the PHARMO system, which includes information of hospital admissions and drug dispensing for all 450,000 residents of 8 Dutch cities. The drug-dispensing record obtained from pharmacy files are complete, and are linked nationwide to the patient's hospital discharge records with a sensitivity and specificity of 95%. Samples included women aged 15-49 years without a history of prior VTE, oral anticoagulants, depot hormone preparations, cardiovascular drugs, the "morning after pill", or hospitalization for any reason in the 2 months before start of OC use. Results suggest that the difference in VTE risk between second and third generation OC is highest among the youngest women who use OC for the first time. However, it might be argued that among these young women, all those with an increased susceptibility for VTE are still present.