Females Account for 1 in 5 Mild Hemophilia Cases at US Centers

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by Margarida Maia |

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Nearly one-fifth of patients with mild hemophilia admitted to treatment centers in the U.S. are female, according to a large study of nearly 30,000 people.

Yet, women and girls make up a smaller proportion of patients with severe or moderate hemophilia, ranging from less than 0.5% to a little more than 1%. These findings, nevertheless, highlight the needs for specialized care based on disease severity for females with hemophilia, the researchers wrote.

The study, “Women and girls with haemophilia receiving care at specialized haemophilia treatment centres in the United States,” was published in the journal Haemophilia.

Mild hemophilia often goes undiagnosed in women and girls, as they may present mild bleeding symptoms due to low levels of some of the clotting factors needed for normal blood clotting. However, they may bleed more than expected during surgery or following an injury.

“The actual number of females requiring care is unknown,” the researchers wrote. “Estimates would be useful for health care planning and resource management.”

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To get an estimate of the number of females with hemophilia receiving specialized care in the U.S., the researchers collected data from all people with a bleeding disorder who visited a hemophilia treatment center for diagnosis or care from January 2012 to September 2020.

During this period, a total of 27,232 people (23,728 males and 3,504 females) with hemophilia A or B visited one of the 139 federally supported centers at least once.

A total of 23,196 males (98%) and 1,667 females (48%) met a diagnosis for severe, moderate, or mild hemophilia.

Hemophilia was classified as severe if clotting factor activity level was less than 1% of normal; moderate if it was 1%–5% of normal; and mild if it was 5%–40% of normal.

A small proportion of moderate or severe hemophilia cases, ranging from less than 0.5% to little over 1%, involved female patients. For mild hemophilia, however, this proportion was higher, accounting for nearly 18% of all cases.

Females with mild hemophilia had higher clotting activity levels than males. For those with hemophilia A, which is caused by a missing or defective factor VIII, clotting activity was 27% in females and 15% in males. For hemophilia type B, which is caused by a missing or defective factor IX, clotting activity was 26% in females and 13% in males.

Males were younger by a mean average of three years (28 vs. 31 years), and were more likely to have a history of infection with the human immunodeficiency virus or the hepatitis C virus, including those with severe hemophilia. However, females were two times more likely than males to have an unknown infection status.

Females with mild hemophilia were also more often uninsured than males (7.2% vs. 4.2%).

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Among all people who visited a hemophilia treatment center, “females were much less likely to have had their factor levels measured, which is recommended for all of those undergoing genetic testing, as well as being required for treatment decisions,” the researchers wrote.

“Classification of females for treatment purposes should be based on their factor activity levels and history, rather than the genetic basis for their disease,” they added.

Diagnosing women and girls with low clotting activity would allow them “to receive appropriate treatment and reimbursement for care and, perhaps, decrease their reported negative experiences with the health care system.”