Hormone Replacement Therapy and Prothrombotic Variants

BACKGROUND:

Estrogens are prothrombotic. Recently, the Heart and Estrogen/progestin Replacement Study (HERS), renewed interest in the adverse effects of hormone replacement therapy (HRT). In HERS, HRT was no better than placebo at preventing coronary events. In post hoc analyses, treatment was associated with early harm and late benefit. In an American Heart Association funded case-control study, a potential interaction was observed between HRT and the prothrombin G20210A variant on the risk of first myocardial infarction (MI) in post-menopausal women with hypertension.

DESIGN NARRATIVE:

The study has a case-control design. The Group Health Cooperative (GHC) computerized files will be used to identify postmenopausal women, aged 30 to 79 yrs, with incident myocardial infarction (MI) or stroke during 1/2000-12/2004. Population-based controls, sampled from the GHC enrollment files, will be frequency matched to cases by age, calendar year, and treated hypertension. Data collection will include medical-record review, telephone interview of consenting subjects, and venous-blood collection. Standard methods will be used to assay variant alleles. The GHC computerized pharmacy records will serve as the primary source of information about the use of HRT. Data analysis will involve restriction, stratification, and logistic regression. Case-control and case-only analyses are planned. There will be a total of 600 MI cases, 420 stroke cases and 1800 controls.

The primary purpose is to examine the potential interactions of hormone replacement therapy with other procoagulant variants on the risk of cardiovascular events. The main variants of interest are: (la) factor XIIIA Val34Leu; (ib) platelet glycoprotein (PGP) Jib Ile843Ser; (ic) PGP IIIa Leu33Pro; and (id) PGP Ia C807T. The secondary aims include the assessment of other drug-gene, risk-factor-gene or gene-gene interactions on risk: (2a) the interaction between PGP IIb Ser843, PGP lila Leu33Pro and PGP Ia C807T and traditional cardiovascular risk factors such as smoking and obesity on the risk of MI and stroke; (2b) the interaction between three coagulation factor XIII polymorphisms and PAl-1 4G/5G on the risk of stroke in women; and (2c) the interaction between aspirin use and glycoprotein IIIa Leu33Pro on the risk of MI and stroke.