Prothrombotic mutations, hormone therapy, and venous thromboembolism among postmenopausal women: impact of the route of estrogen administration.
BACKGROUND
Oral estrogen increases the risk of venous thromboembolism (VTE) in postmenopausal women, particularly in those with a prothrombotic mutation. Transdermal estrogen may be safe with respect to VTE. We investigated the impact of the route of estrogen administration on the association between a prothrombotic mutation (factor V Leiden or prothrombin G20210A mutation) and VTE risk.


RESULTS
We performed a multicenter case-control study of VTE among postmenopausal women who were enrolled in 1999 through 2004 at 7 clinical centers in France. We recruited 235 consecutive patients with a first documented episode of idiopathic VTE and 554 controls. Factor V Leiden was associated with a 3.4-fold-increased risk of VTE (95% confidence interval [CI], 2.0 to 5.8), and a prothrombin mutation was associated with a 4.8-fold-increased risk of VTE (95% CI, 2.5 to 9.4). Oral but not transdermal estrogen was associated with an increased risk of VTE (odds ratio [OR], 4.3; 95% CI, 2.6 to 7.2; and OR, 1.2; 95% CI, 0.8 to 1.7, respectively). After adjustment for potential confounding factors, the combination of either factor V Leiden or prothrombin G20210A mutation and oral estrogen gave a 25-fold-increased risk of VTE compared with nonusers without mutation (95% CI, 6.9 to 95.0). However, the risk for women with prothrombotic mutation using transdermal estrogen was similar to that of women with a mutation who were not using estrogen (OR, 4.4; 95% CI, 2.0 to 9.9; and OR, 4.1; 95% CI, 2.3 to 7.4, respectively).


CONCLUSIONS
In contrast to oral estrogen, transdermal estrogen does not confer additional risk on women who carry a prothrombotic mutation. The safety of transdermal estrogen has to be confirmed in randomized trials.
Straczek
Céline
C
INSERM, Cardiovascular Epidemiology Unit, Villejuif, France.
Oger
Emmanuel
E
Yon de Jonage-Canonico
Marianne Beau
MB
Plu-Bureau
Geneviève
G
Conard
Jacqueline
J
Meyer
Guy
G
Alhenc-Gelas
Martine
M
Lévesque
Hervé
H
Trillot
Nathalie
N
Barrellier
Marie-Thérèse
MT
Wahl
Denis
D
Emmerich
Joseph
J
Scarabin
Pierre-Yves
PY
D000368:Aged; D016022:Case-Control Studies; D004333:Drug Administration Routes; D004967:Estrogens / Q000008:administration & dosage* / Q000009:adverse effects; D005165:Factor V; D005260:Female; D020249:Hormone Replacement Therapy / Q000009:adverse effects*; D006801:Humans; D008875:Middle Aged; D009154:Mutation; D020125:Mutation, Missense; D017698:Postmenopause / Q000502:physiology*; D011516:Prothrombin / Q000235:genetics; D012307:Risk Factors; D013923:Thromboembolism / Q000453:epidemiology / Q000209:etiology; D019851:Thrombophilia / Q000235:genetics*; D020246:Venous Thrombosis / Q000453:epidemiology / Q000209:etiology*
D004967:Estrogens; C095381:factor V Leiden; D005165:Factor V; D011516:Prothrombin