Myocardial infarction and oral contraceptives, a retrospective case control study in England and Scotland ('MICA' Study)

Abstract

Recent studies have shown that modern (third generation), oral contraceptives (OC) are associated with an increased incidence of venous thromboembolic disease compared to older (second generation), OC. It is not known, however, whether this association is also true for arterial thrombosis, in particular myocardial infarction. In fact, it has been suggested that third generation OC may even be protective against myocardial infarction (MI), compared to second generation OC. The protocol for a multicentre case-control study, involving the whole of England and Scotland, is described. Cases will be female patients aged 16-44 years, who suffered an MI between 1.10.93 and 1.10.95. Controls will be drawn from the community, using the GP list, to which the case belonged. Odds ratios will be calculated primarily to compare current users of third generation OC with current users of second generation OC.