Stroke

• The baseline risk of stroke for women is age related and overall, the risk is low in women under 60 years.
• Risk differs between ethnic groups and may be greater in Black people.
• Oral oestrogen is associated with a small increase in the risk of stroke, and this effect is likely to be dose related.
• In contrast, transdermal oestrogen, transdermal combined preparations and micronised progesterone appear unlikely to increase risk of stroke above baseline risk.

NICE says:

• Combined or oestrogen only HRT containing transdermal oestrogen is unlikely to increase the risk of stroke when given at standard therapeutic dosage.
• Combined HRT containing oral oestrogen increases the risk of stroke, and the increase rises with higher oestrogen doses and longer duration of treatment.
• Oestrogen only oral HRT increases the risk of stroke, and the increase rises with dosage and is greater if the HRT is started after the age of 60 years.

• Very few studies have looked at the effect of HRT on pre-existing atherosclerotic plaques and any risk of subsequent plaque destabilisation. This is not well understood and represents an ongoing area of uncertainty.

• HRT does not increase the risk of haemorrhagic stroke.