The objectives of the study were to characterize and compare the risks
of short and long-term use of DRSP-containing OCs and established OCs
in a study population that is representative for the actual users of the
individual preparations. This includes an estimate of the absolute risk
of rare adverse events.
The main clinical outcome of interest was the occurrence of cardiovascular
events, i.e. incidence rates of arrhythmias, myocardial infarction, stroke,
venous thromboembolism, and sudden death between users of DRSP-containing
OCs and users of established OCs.
Based on the fact that European regulatory authorities considered the
progestin levonorgestrel (LNG) to have the least impact on VTE risk, it
was decided that the primary cardiovascular outcome of interest should
be the VTE hazard ratio between users of DRSP-containing OCs and users
of LNG-containing OCs.
Other objectives of the study were to analyze the drug utilization pattern
of DRSP-containing OCs and established OCs, and to characterize the baseline
risk for users of the individual formulations (lifetime history of co-morbidity,
risk factors, co-medication, socio-demographic and lifestyle data). Additionally,
all other clinical outcomes including contraceptive failure and return
to fertility after cessation of OC use were to be recorded.