Use of hormone therapy (HT) among Swedish women with contraindications - A pharmacoepidemiological cohort study.

Objectives: To assess how women in Sweden with breast cancer (BC), endometrial cancer (EC), and/or pulmonary embolism (PE) were dispensed menopausal hormone therapy (HT).
Study Design: A retrospective study of Swedish women aged 40 years or more on 31 December 2005 (n = 2,863,643), followed through to December 2011. The study analysed three mandatory national healthcare registries: the Swedish Prescribed Drug Register, the National Inpatient Register and the Cancer Register. New users were defined as having a first dispensation after at least a 9-month break, and thus were possible to identify from April 2006. New users with at least one of the diagnoses BC, EC or PE before the first dispensation were classified as having a relative or absolute contraindication for HT.
Main Outcome Measures: The relative risks of having HT dispensed after being diagnosed with BC, EC and/or PE.
Results: In total, 171,714 women had at least one of the diagnoses BC, EC or PE. The relative risk of having hormone therapy dispensed (current and new users) after being diagnosed with any of the diagnoses was significantly lower (PE, IRR 0.11, 95% CI 0.10-0.12;/ BC, IRR 0.12, 95% CI 0.11-0.13; EC, IRR 0.43, CI 0.40-0.46) than for women without these diagnoses.
Conclusions: One in about 250 women started treatment with HT after being diagnosed with BC, PE or EC. Swedish prescribers seem to be well aware of the recommendations for HT use in women with contraindications. A few women, however, are prescribed HT despite having BC, EC or PE, possibly after careful evaluation of the risks and benefits and giving informed consent. Women with a history of PE were prescribed transdermal HT to a larger extent than women in general, in line with results from observational studies.
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