Young women are more likely to have an ischaemic stroke than young men despite having fewer traditional cardiovascular risk factors, US researchers say.

However, this sex difference flips as patients get older, with the prevalence of stroke significantly higher in males aged between 45 and 74, the retrospective cohort study shows.

The University of Colorado-led team analysed data from a 10% random sample of 5.8 million insured enrollees in a nationally representative claims database between 2001 and 2014 to assess sex differences in the incidence of stroke in young adults (under-55s).

Of the 20,500 index strokes identified (mean age 63), half of the events occurred in women and one quarter occurred among those aged 15-54.