title: Extended case-control study results on thromboembolic outcomes among transdermal contraceptive users.
abstract: BACKGROUND
  We extended an earlier study that found a twofold higher risk of venous thromboembolism (VTE) associated with the transdermal contraceptive system relative to norgestimate-containing oral contraceptives (NGM-OC).
  
  
  METHODS
  This case-control study identified potential cases of VTE, acute myocardial infarction (AMI) and stroke from 24 months of additional health care claims, with adjudication via medical records. Randomly selected controls were matched to cases on age (15-44 years) and characteristics of contraception use. Conditional logistic regression models provided odds ratios (ORs) and 95% confidence intervals (CIs).
  
  
  RESULTS
  The transdermal contraceptive system was associated with a twofold higher risk of VTE (OR 2.0; 95% CI 1.2-3.3) compared with users of NGM-OC. The OR for stroke was 0.6 (95% CI 0.1-3.2) and for AMI 1.2 (95% CI 0.3-4.7).
  
  
  CONCLUSIONS
  This extension was consistent with the earlier study, showing a twofold increased risk of VTE associated with use of the transdermal contraceptive system relative to NGM-OC.
authors.affiliation: i3 Drug Safety, Waltham, MA 02451, USA. david.dore@i3drugsafety.com
authors.forename: David D
authors.initials: DD
authors.lastname: Dore
authors.forename: Heather
authors.initials: H
authors.lastname: Norman
authors.forename: Jeanne
authors.initials: J
authors.lastname: Loughlin
authors.forename: John D
authors.initials: JD
authors.lastname: Seeger
mesh_terms: D000279:Administration, Cutaneous; D000328:Adult; D016022:Case-Control Studies; D003277:Contraceptives, Oral, Combined / Q000009:adverse effects; D004338:Drug Combinations; D004997:Ethinyl Estradiol / Q000008:administration & dosage / Q000009:adverse effects*; D005260:Female; D006801:Humans; D009203:Myocardial Infarction / Q000209:etiology*; D009644:Norgestrel / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives*; D018570:Risk Assessment; D020521:Stroke / Q000209:etiology*; D054556:Venous Thromboembolism / Q000209:etiology*
chemical_list: D003277:Contraceptives, Oral, Combined; D004338:Drug Combinations; C511292:Ortho Evra; D009644:Norgestrel; D004997:Ethinyl Estradiol