A New Study of Hemophilia Occurrence Finds Many More Cases in the United States
Hemophilia is an inherited bleeding disorder in which the blood does not clot properly due to a lack or decrease in a protein called clotting factor. The two most common types of hemophilia are hemophilia A, which is due to a lack of clotting factor VIII (8) and hemophilia B, which is due to a lack of clotting factor IX (9). Either type can lead to spontaneous bleeding into muscles, organs, and joints as well as prolonged bleeding following injuries or surgery. The condition primarily affects males.
The complications of hemophilia can be severe, and treatment is often expensive. It is important to know how many people in the United States have hemophilia. This information can be used to understand the healthcare needs of those living with hemophilia, and thus, aid in service planning.
In the early 1990s, the Centers for Disease Control and Prevention (CDC) conducted a study with health departments in six U.S. states to count the number of males with hemophilia in those states. Using those results, the researchers estimated that 18,000 males in the United States had hemophilia. Additionally, about two-thirds of these individuals were receiving care in the U.S. network of specialized and comprehensive Hemophilia Treatment Centers (HTCs).
About this Study
Researchers from CDC and the U.S. HTC Network conducted a study using data collected during 2012–2018 on all male patients who visited federally supported U.S. HTCs. The study aimed to
- Update the estimated number of males with hemophilia currently living in the United States; and
- Estimate the birth rate of new cases in the United States each year.
Prevalence is a statistical concept referring to the number of cases of a disease that are present in a particular population at a given time, whereas incidence refers to the number of new cases that develop in a given period of time.
Main Findings from this Study
- The current number of males with hemophilia living in the United States is estimated to be between 30,000 and 33,000.
- The estimated prevalence of hemophilia in the United States is 12 cases per 100,000 U.S. males for hemophilia A and 3.7 cases per 100,000 U.S. males for hemophilia B.
- Hemophilia prevalence varies widely across the United States and is highest in Midwestern and Northeastern states.
- The estimated incidence of hemophilia among U.S. births is 1 birth per 5,617 male births for hemophilia A and 1 birth per 19,283 male births for hemophilia B.
- Among all males with hemophilia, just over 4 in 10 have the severe form of the disorder.
- The average age of persons with hemophilia in the United States is 23.5 years.
- Compared to the distribution of race and ethnicity in the U.S. population, white race is more common, Hispanic ethnicity is equally common, while black race and Asian ancestry are less common among persons with hemophilia.
Critical Gaps & Future Directions
A number of observations from this study need further investigation:
- The large variation in the prevalence of hemophilia between states is thought to be due primarily to the hereditary (passed down from one’s parents) nature of hemophilia and known migratory patterns (when people with hemophilia moved between states) early in U.S. history. It may be possible, however, that some of the differences may be due to differences between states in access to hemophilia care.
- The reason for the decreased prevalence of hemophilia among people of black race is not known.
- The young age of the hemophilia population is likely due to high death rates in the 1980s and 1990s due to infections from HIV and infection-related complications from hepatitis C resulting from exposure to contaminated treatment products. It is also possible that older patients may not be receiving care in HTCs, and thus, would not have been counted in our study.
- Our study included only those who received care in an HTC during the time period. It is known that not all people with hemophilia receive care in a federally supported HTC.
More work is needed to get a better estimate of how many people living with hemophilia do not utilize HTCs for their care. It would also be important to know whether the health of this group differs from the health of people with hemophilia who are cared for in the HTCs. Similar studies are needed to assess the size and characteristics of women with hemophilia A and B.
For more information about Hemophilia, please visit our Hemophilia webpages.
Soucie JM, Miller CH, Dupervil B, Le B, Buckner TW. Occurrence rates of haemophilia among males in the United States based on surveillance conducted in specialized haemophilia treatment centres. Haemophilia 2020; 26:487-93.