New research from Queen Mary University of London, published in iScience, shows an increased risk of blood clots in women who have any combination of Factor V Leiden gene mutation, oestrogen use, or common medical conditions – specifically: obesity, high blood pressure, high cholesterol, and kidney disease.
Women with the Factor V Leiden (FVL) gene mutation who had been prescribed oestrogen had more than double the risk of blood clotting compared to women who did not have this mutation. And almost 20% of the women who carry FVL, were prescribed oestrogen and had two medical conditions suffered a blood clot. The presence of the FVL gene made a substantial difference to risk, with only around 5% of women taking oestrogen and having two conditions suffering a clotting event.
The study also found that a woman with obesity, hypertension, high cholesterol, and kidney disease (not uncommon in a clinical setting) had an 8 times greater chance of blood clotting compared to a woman with none of these conditions. This amounted to roughly one in every six women with the four conditions in the study suffering a blood clot. Three medical conditions meant a five times greater chance of blood clotting, and two medical conditions meant a two times greater chance.
One in three women who had the FVL gene mutation and three of the medical conditions examined also suffered a blood clotting event.
The researchers examined the health data of 20 048 British-Bangladeshi and British-Pakistani women from the Genes & Health project, a large community-based genetics study. While oestrogen use, FVL, and common medical conditions are all known risk factors of blood clots, studies have not looked at the combined risk of these factors together on blood clot prevalence.
Women are commonly prescribed oestrogen, both through oral contraception containing the hormone and as part of post-menopausal hormone replacement therapy.
Professor Sir Mark Caulfield, from Queen Mary University of London, said: “Our study gives a more complete picture of blood clotting in Bangladeshi and Pakistani communities who have previously been underrepresented in research.
“Genetic testing of the FVL gene mutation could give a clearer sense of someone’s personalised risk of this potentially fatal complication if they were prescribed oestrogen.”
Source: Queen Mary University London
