These results support previous trials that have suggested a link between HRT and stroke.
Researchers at the University of Nottingham reviewed the evidence from 28 completed trials involving 39,769 individuals. They assessed the risk of stroke by type, severity, and outcome.
Hormone replacement therapy was associated with an overall 29% increase in the risk of stroke, especially ischaemic stroke (caused by an insufficient blood supply to the brain). The severity of stroke was also increased with hormone replacement therapy.
It remains unclear why HRT should increase ischaemic stroke and its severity when some previous studies have suggested it might have a protective effect, say the authors. However, given these findings, HRT cannot be recommended for the primary or secondary prevention of stroke.