Approximately 30,000 males have hemophilia in the U.S., according to estimates from a recent study, which also found that patients with hemophilia are generally young and that the disease is more common in Northeastern and Midwestern states.
The study, “Occurrence rates of haemophilia among males in the United States based on surveillance conducted in specialized haemophilia treatment centres,” was published in the journal Haemophilia.
Understanding how many people have hemophilia is important to allocate appropriate medical resources to help patients. Research done in the 1990s suggested that about 17,000 males in the U.S. had hemophilia, with an incidence rate of about 1 in 5,000 live male births.
These data were collected during a period of time after the hemophilia community had been hit hard by the HIV epidemic. From the late 1970s to the mid-1980s, about half of all people with hemophilia were infected due to contaminated blood products. Because high mortality rates may have resulted in an underestimate, updated numbers are needed.
Researchers at the Division of Blood Disorders of the Centers for Disease Control and Prevention and their collaborators collected data from 139 hemophilia treatment centers in all 50 states. The study focused on males, who are most affected, as hemophilia is an X-linked condition. If a male inherits an X chromosome with a disease-causing gene from his mother, he will have hemophilia as he has only one X chromosome. Females have two such chromosomes, making the disease rarer in them.
Using data from previous research on the use of specialty centers, the researchers estimated that the total number of people identified represent between 67% and 80% of all males with hemophilia in the U.S. Based on these numbers, the team estimated that between between 29,761 and 32,985 males with the disorder currently live in the U.S.
“We have found that occurrence rates of haemophilia in the United States are higher than previously measured by a population-based study conducted more than 20 years ago,” the scientists wrote.
Compared with the overall population of the U.S., the hemophilia group was disproportionately young — the mean age was 23.5 years, and 75% were younger than 35.
“The higher proportion of youth in the haemophilia population relative to the general population is indicative of the regeneration of a population decimated by the HIV epidemic in the 1980s,” the researchers wrote. “Improvements in treatment are expected to continue to extend the lifespan of people with haemophilia.”
Differences were also seen based on race and location. Relative to the general U.S. population, there were more whites with hemophilia (81% vs. 72.4%), but fewer blacks (11.2% vs. 12.6%) and Asians (3.6% vs. 4.8%). Hispanic ethnicity, regardless of race, was similar among those with hemophilia and the general population (about 16% in both). Also, disease severity was seen comparing all patients to those born after 1994.
Hemophilia had higher prevalence in the Northeast and Midwest, with the highest rates found in Iowa, Indiana, Ohio, Vermont, New Hampshire, and Maine. According to the scientists, this is likely due to founder effects, which is consistent with what is known about how populations migrated early in the history of the U.S.
Slight regional differences were seen between disease types. For instance, New Hampshire and Vermont were among the states with the highest prevalence of type A, but not type B.
“Regional differences in the distribution and severity levels of the patient population may require closer monitoring to ensure that needed resources and services are available to maximize the health and quality of life of people with bleeding disorders,” the researchers wrote.
Using data from the 9,587 males born from 1995 to 2014, the investigators estimated that the overall incidence of hemophilia is 1 in 4,334 live male births. The incidence rate of type A is estimated at 1 in 5,617 and type B at 1 in 19,283.
Rates of hemophilia births appeared to have decreased in more recent years, but the researchers suggested this can most likely be attributed to children with mild disease who remain undiagnosed.
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