Estrogen therapy and risk of cardiovascular events among women with type 2 diabetes

Abstract

OBJECTIVE - To evaluate the association between estrogen therapy and cardiovascular disease risk among women with type 2 diabetes. RESEARCH DESIGN AND METHODS - A retrospective, case-cohort study was conducted among 6,017 women aged 45-80 years with type 2 diabetes from 1 January 1986 to 31 December 1992 at the Group Health Cooperative in Washington state. Cardiovascular outcomes, including nonfatal myocardial infarction (n = 215), coronary revascularization (n = 253), and cardiovascular deaths (n = 229), were ascertained through 31 December 1998. Use of estrogen and progestin was derived from automated pharmacy records and modeled as a time-dependent variable Median follow-up was 6.8 years. Multivariable-adjusted relative risk (RR) and 95% CI were calculated using Cox proportional hazard models for case-cohort analyses. RESULTS - Current use of estrogen with (RR 0.43, 95% CI 0.22-0.85) or without (0.48, 0.30-0.78) progestin was associated with a decreased risk of cardiovascular events compared with never having used estrogen. Risk of cardiovascular events associated with a first episode of estrogen use (with or without progestin) of <25 months' duration (1.12, 0.49-2.54), first episode of use ≥25 months' duration (0.32, 0.06-1.70), and current use that was not the first episode of use (0.42, 0.42-0.67) indicated that recent initiation was not associated with an increase or decrease in risk. CONCLUSIONS - These results show an association of estrogen therapy, with or without progestin, with decreased risk of cardiovascular events among women with type 2 diabetes. This association should be further investigated in large randomized, controlled trials.