ORTHO EVRA is a newly developed transdermal contraceptive system (a "patch") available in the U.S. since April 2002. The study uses data from the PHARMetrics database to assess the occurrence of venous thromboembolism, ischemic stroke, and acute myocardial infarction in current users of ORTHO EVRA compared to current users of norgestimate-containing oral contraceptives with 35 mcg ethinyl estradiol. The PHARMetrics database is an ongoing longitudinal database with information on about 17 million people; it is made up of data contributed by managed care plans in the United States and contains information on paid claims for pharmaceuticals, medical diagnoses and procedures, and demographic information. There will be 3 sets of cases reflecting women who have a first-time recorded claim for an ICD-9 diagnosis during the study period (a) venous thrombosis or pulmonary embolism with hospitalization during the study period and who had subsequent claims for anticoagulant treatment, (b) ischemic stroke and who were hospitalized, (c) acute myocardial infarction or acute coronary revascularization and who were hospitalized. Three separate sets of controls will be identified for each outcome. One analysis will estimate the relative risk of idiopathic ischemic stroke or myocardial infarction, and another analysis will estimate the relative risk of idiopathic venous thromboembolism (deep vein thrombosis or pulmonary embolism). Conditional logistic regression will be used. Analyses will be stratified by calendar year. The analyses will be repeated including non-idiopathic cases of venous thromboembolism, stroke, and heart attacks.

A transdermal patch containing 6 mg NGM and 0.75 mg EE is worn for 1 week and replaced for 3 consecutive weeks; the fourth week is patch-free. Monophasic or triphasic oral contraceptive pill is taken for 21 consecutive days followed by no pill or a drug-free pill for 7 days.