The LASS Study is a large, multinational, prospective, controlled, non-interventional, long-term cohort study that follows a series of cohorts. The cohorts consist of new users (first-ever users, switchers and restarters) of three different groups of oral contraceptives (OCs): OCs containing drospirenone (DRSP), OCs containing levonorgestrel (LNG) and OCs containing other progestogens. A "non-interference" approach is used to provide standardized, comprehensive, reliable information on these groups of OCs under routine medical conditions.
The main clinical outcomes of interest for the long-term follow-up are arterial and venous thromboembolism as well as breast cancer. Regular, active contacts with the cohort members (=active surveillance) provide all necessary information on health-related events or changes in health status.
The study is based on the existing long-term EURAS cohorts who are still in follow-up. LASS succeeds EURAS and prolongs the follow-up period for another five years. Total follow-up time of members of the long-term cohorts will be between 6 and 10 years. By means of annual contacts almost all relevant clinical outcomes will be captured. This will be accomplished by contacting the relevant physicians and by reviewing relevant source documents in the case of relevant clinical outcomes.
