The European Active Surveillance Study on OC Prescribing Practice, Benefits and Safety (EURAS)

Active surveillance using valid epidemiologic study designs is desirable for any new product, because adverse effects may occur that have not yet been identified in pre-marketing studies.

The EURAS study investigates the safety of oral contraceptives with a large cohort of women attending offices of prescribing physicians. Its primary objective will be to compare incidence rates of adverse events in users of so-called new OCs and users of other OCs. The study is conducted as a phase IV commitment to the European Drug Authorities.

The combined cohort will include 50,000 to 60,000 women recruited by a selected set of physicians in six European countries. A total of more than 1,500,000 cycles are expected to be observed during the field work which will start early in 2001 and end early in 2006.

The participating women will undergo a baseline survey using a self administered questionnaire to describe the baseline risk. Every six months they will fill out a questionnaire in which they will record complaints and events during the use of the prescribed OC which will be validated. A multifaceted 4-level follow-up procedure will be established to ensure low loss to follow-up rates.

Based on experience obtained in previous OC studies complex sources of bias and confounding are expected. Thus, multivariate methods such as Cox regression will be used to adjust for confounding. Regarding the impact of the results on public health, the main emphasis will be on the absolute risk estimates.