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Rare adverse drug reactions (ADRs) to combined oral contraceptives (COCs), such as venous thromboembolism (VTE), are seldom disclosed until a COC has been on the market for some time. Two new COCs, Yasmin and Cilest have recently been launched in several European countries with expectations of being safer than older COCs. Utilising data from spontaneous reporting of ADRs to the Medical Products Agency in Sweden and sales data, VTE incidence for Yasmin and Cilest was estimated and compared with VTE incidence for a second (Follimin) and a third generation (Desolett) COC. The reported VTE incidence for Yasmin and Cilest was higher 4.6, and 3.7 per 10,000 users per year, respectively than the corresponding VTE incidences for Follimin and Desolett of 1.9 and 2.9 per 10,000 users per year, respectively. The differences were, however, not statistically significant. We conclude that the risk of VTE associated with the most recent COCs is at least similar to that of older COCs.

A questionnaire revealed that nearly 40 000 examinations of clinically suspected deep venous thrombosis (DVT) were performed in Sweden in 2001, with a slight predominance of phlebographies. In about two thirds of all cases the deep muscle veins of the calf were included in the interpretation when phlebography was performed, but in less than one fifth when Doppler sonography (CDU) was used. In more than half of the cases a negative CDU was not followed by phlebograghy. On the other hand, the combination of CDU and phlebography was routinely used in nearly two thirds of all ambiguous cases. The interpretation of nonfiling of contrast medium in vein segments on phlebography varied from DVT to no DVT. Most of the phlebographies were performed with digital X-ray technique.

The spontaneous reporting system in Sweden is based on reporting by health care professionals of adverse drug reactions (ADRs) to the Medical Products Agency. The usefulness of the spontaneous reporting system is limited by a substantial degree of underreporting. In order to study factors that make reporting of ADRs difficult as well as to obtain responses to suggestions that could increase the reporting of ADRs, an enquiry was sent to 300 randomly selected physicians. The most important factors that make reporting of ADRs more difficult are lack of time and forgetfulness. Most physicians stated that they would report ADRs to a greater extent if reporting was simpler, if resources were available or if the response to the reporting was improved. The majority of the physicians who had a computer at work stated that they would like to access the reporting form electronically.