title: Hormonal contraception and risk of venous thromboembolism: national follow-up study.
abstract: OBJECTIVE
  To assess the risk of venous thrombosis in current users of different types of hormonal contraception, focusing on regimen, oestrogen dose, type of progestogen, and route of administration.
  
  
  METHODS
  National cohort study.
  
  
  METHODS
  Denmark, 1995-2005.
  
  
  METHODS
  Danish women aged 15-49 with no history of cardiovascular or malignant disease.
  
  
  METHODS
  Adjusted rate ratios for all first time deep venous thrombosis, portal thrombosis, thrombosis of caval vein, thrombosis of renal vein, unspecified deep vein thrombosis, and pulmonary embolism during the study period.
  
  
  RESULTS
  10.4 million woman years were recorded, 3.3 million woman years in receipt of oral contraceptives. In total, 4213 venous thrombotic events were observed, 2045 in current users of oral contraceptives. The overall absolute risk of venous thrombosis per 10 000 woman years in non-users of oral contraceptives was 3.01 and in current users was 6.29. Compared with non-users of combined oral contraceptives the rate ratio of venous thrombembolism in current users decreased with duration of use (<1 year 4.17, 95% confidence interval 3.73 to 4.66, 1-4 years 2.98, 2.73 to 3.26, and >4 years 2.76, 2.53 to 3.02; P<0.001) and with decreasing dose of oestrogen. Compared with oral contraceptives containing levonorgestrel and with the same dose of oestrogen and length of use, the rate ratio for oral contraceptives with norethisterone was 0.98 (0.71 to 1.37), with norgestimate 1.19 (0.96 to 1.47), with desogestrel 1.82 (1.49 to 2.22), with gestodene 1.86 (1.59 to 2.18), with drospirenone 1.64 (1.27 to 2.10), and with cyproterone 1.88 (1.47 to 2.42). Compared with non-users of oral contraceptives, the rate ratio for venous thromboembolism in users of progestogen only oral contraceptives with levonorgestrel or norethisterone was 0.59 (0.33 to 1.03) or with 75 mug desogestrel was 1.12 (0.36 to 3.49), and for hormone releasing intrauterine devices was 0.90 (0.64 to 1.26).
  
  
  CONCLUSIONS
  The risk of venous thrombosis in current users of combined oral contraceptives decreases with duration of use and decreasing oestrogen dose. For the same dose of oestrogen and the same length of use, oral contraceptives with desogestrel, gestodene, or drospirenone were associated with a significantly higher risk of venous thrombosis than oral contraceptives with levonorgestrel. Progestogen only pills and hormone releasing intrauterine devices were not associated with any increased risk of venous thrombosis.
authors.affiliation: Gynaecological Clinic, Rigshospitalet, Copenhagen University, DK-2100 Copenhagen, Denmark. Lidegaard@rh.regionh.dk
authors.forename: Øjvind
authors.initials: Ø
authors.lastname: Lidegaard
authors.forename: Ellen
authors.initials: E
authors.lastname: Løkkegaard
authors.forename: Anne Louise
authors.initials: AL
authors.lastname: Svendsen
authors.forename: Carsten
authors.initials: C
authors.lastname: Agger
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D003277:Contraceptives, Oral, Combined / Q000009:adverse effects; D003278:Contraceptives, Oral, Hormonal / Q000009:adverse effects*; D003718:Denmark / Q000453:epidemiology; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008875:Middle Aged; D054556:Venous Thromboembolism / Q000139:chemically induced* / Q000453:epidemiology; D055815:Young Adult
chemical_list: D003277:Contraceptives, Oral, Combined; D003278:Contraceptives, Oral, Hormonal
references.citation: Contraception. 2002 Mar;65(3):187-96
references.pmid: 11929640
references.citation: Arch Intern Med. 1999 Jan 11;159(1):65-70
references.pmid: 9892332
references.citation: Lancet. 1995 Dec 16;346(8990):1575-82
references.pmid: 7500748
references.citation: Contraception. 2006 Mar;73(3):223-8
references.pmid: 16472560
references.citation: Lancet. 2000 Jun 17;355(9221):2133-4
references.pmid: 10902629
references.citation: Obstet Gynecol. 2007 Sep;110(3):587-93
references.pmid: 17766604
references.citation: Lancet. 2001 Oct 27;358(9291):1427-9
references.pmid: 11705493
references.citation: Br J Clin Pharmacol. 2005 Jul;60(1):98-102
references.pmid: 15963100
references.citation: Lancet. 1995 Dec 16;346(8990):1589-93
references.pmid: 7500750
references.citation: Hum Reprod. 1999 Jun;14(6):1500-5
references.pmid: 10357966
references.citation: BMJ. 1996 Jan 13;312(7023):83-8
references.pmid: 8555935
references.citation: Lancet. 1997 Jan 11;349(9045):83-8
references.pmid: 8996419
references.citation: Contraception. 2007 May;75(5):344-54
references.pmid: 17434015
references.citation: Lancet. 1995 Dec 16;346(8990):1582-8
references.pmid: 7500749
references.citation: Hum Reprod. 1999 Jun;14(6):1493-9
references.pmid: 10359554
references.citation: Lancet. 1995 Dec 16;346(8990):1593-6
references.pmid: 7500751
references.citation: Acta Obstet Gynecol Scand. 1997 Mar;76(3):252-60
references.pmid: 9093141
references.citation: BMJ. 2000 Nov 11;321(7270):1190-5
references.pmid: 11073511