A new study which examined the association between the use of different types of hormone replacement therapy (HRT) and the risk of venous thromboembolism (VTE) has found that while oral preparations are linked with an increased risk of VTE, there is no increased risk with transdermal preparations.
Researchers examined data on HRT records of 80,396 women aged 40-79 years with a primary diagnosis of VTE between 1998 and 2017, and 391,494 matched female controls.
Overall, 5,795 (7.2%) women who had VTE and 21,670 (5.5%) controls had been exposed to HRT within 90 days before the index date.
Most oral preparations were found to be associated with increased VTE risk compared with no HRT. Compared with no exposure, conjugated equine oestrogen preparations, with and without medroxyprogesterone acetate, were associated with the highest risks while oestradiol with dydrogesterone had the lowest risk. No increased VTE risk was found for transdermal preparations or with tibolone.
Presenting the findings in the BMJ, the authors noted a number of limitations including that some preparations were not sufficiently prescribed to be assessed individually. However, they say the findings can help clinicians and women make better treatment choices.