Menopausal HT type does not affect risk for venous thromboembolism
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Risk for venous thromboembolism does not differ for women using oral conjugated equine estrogen vs. oral or transdermal estradiol, according to a study published in Menopause.
“In this pharmacoepidemiologic comparative cohort study of Veterans Health Administration women, about 2 in 1,000 women using hormone therapy per year experienced a VTE event, with a similar burden of risk among the different estrogen subtypes and between oral vs. transdermal routes,” Marc Blondon, MD, MS, an internist in the division of angiology and hemostasis at Geneva University Hospitals and Faculty of Medicine, and colleagues wrote. “Similar relative risks among the HT subtypes were also observed in an analysis restricted to new users of HT.”
Researchers collected data from Veterans Health Administration records in the U.S. of perimenopausal and postmenopausal women who were using HT on Jan. 1, 2003, or started using HT after that date through Dec. 31, 2011. Women with a record of a dispensed prescription for HT were included in the study. All medications were classified as either oral conjugated equine estrogen, oral estradiol, transdermal estradiol or other. Progestogen preparations were also identified. Incident HT users were women who had their first prescription for HT during the study period and had not filled a prescription since at least 1 year before cohort entry.
Diagnostic codes from hospitalizations and outpatient visits were used to identify potential VTE cases and to confirm these took place during HT use. Pulmonary embolism cases were considered definite if there was a positive pulmonary angiogram, CT or lung scan, and probable if there was a physician-reported diagnosis. Deep vein thrombosis cases were considered definite if there was a positive venogram, compression ultrasound or CT, and were considered possible if there was a physician-reported diagnosis or equivocal imaging.
There were 123 definite cases of VTE and 91 possible cases among 51,571 women (median age, 52 years; 74% white). Of the study cohort, 40% had obesity and 41% had hypertension.
Women with a BMI of 30 kg/m2 or higher had an increased risk for VTE compared with those with a BMI less than 25 kg/m2 (HR = 1.62; 95% CI, 1.15-2.28). Women older than 75 years also had a higher risk for VTE compared with those aged 60 years or younger (HR = 2.72; 95% CI, 1.78-4.15).
There were no differences in the risk for incident VTE among users of oral estradiol or transdermal estradiol compared with those using oral conjugated equine estrogen. The findings were unchanged in analysis restricted the incident users, and the use of progestogen did not modify the associations.
Researchers said the findings contrast with previous studies showing a lower risk for VTE with oral or transdermal estradiol use compared with use of oral conjugated equine estrogen, and there are several possible reasons for the different findings.
“We do not believe that our null findings are explained by methodological biases,” the researchers wrote. “It may be that our sample is prone to confounding by lifestyle variables that cannot be adjusted for, such as diet and physical activity. It may also be that, among women with a high number of comedications, in particular psychotropic and opioid drugs, differential effects of estrogen and routes are truly not present.”
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