In my rabbit hole of menopause research, I was looking at estrogen replacement therapy and blood clot risk. We use a screening tool for clot risk before surgery, and in it is a box for “hormone replacement therapy.” If you are on any kind of hormone, we check the box. It was my understanding that hormone increased the risk of blood clot in any form.
Not so fast.
In my menopause research, I saw a statement that the transdermal hormone patches don’t increase the risk like oral hormone replacement does. So I went to my trusted PubMed to find out.
Use of hormone replacement therapy and risk of venous thromboembolism: nested case-control studies using the QResearch and CPRD databases, in the British Medical Journal 2019.
In this study they looked to see the risk for DVT of different kinds of hormone replacement.
- 80,396 women aged 40-79 blood clots between 1998 and 2017 matched to 391,494 controls.
- Adjusted for demographics, smoking status, alcohol consumption, comorbidities, recent medical events, and other prescribed drugs.
- 7.2% women on HRT had DVT vs. 5.5% controls
- 85% had oral HRT use, associated with a significantly increased risk of blood clot compared with no exposure
- This was found with oestrogen only preparations (1.40, 1.32 to 1.48) and combined preparations (1.73, 1.65 to 1.81).
- Estradiol had a lower risk than conjugated equine oestrogen
- Compared with no exposure, conjugated equine oestrogen with medroxyprogesterone acetate had the highest risk (2.10, 1.92 to 2.31),
- Estradiol with dydrogesterone had the lowest risk (1.18, 0.98 to 1.42).
- Transdermal preparations were not associated with risk of venous thromboembolism, which was consistent for different regimens (overall adjusted odds ratio 0.93, 95% confidence interval 0.87 to 1.01).
They concluded that transdermal preparations are underused and safer.
My thoughts?
Good to know. This was a large study, and seems to clearly indicate for those at risk for blood clots, there may be a good method for giving hormone replacement. (And if you are at high risk for a blood clot, that the oral versions are higher risk. Of the oral versions estradiol with dydrogesterone was the lowest risk)