Scientists report that hemophilia is three times more prevalent in men worldwide than previously thought and still associated with a poorer life expectancy, especially in low-income countries.
Findings of the study, “Establishing the Prevalence and Prevalence at Birth of Hemophilia in Males: A Meta-analytic Approach Using National Registries,” were published in the Annals of Internal Medicine.
This observational study came in response to a call by the World Federation of Hemophilia to more accurately measure the disease’s prevalence and its impact on life expectancy.
Hemophilia is a genetic disorder marked by an inability to form blood clots to prevent excessive bleeding. In hemophilia A, this inability is caused by the lack of a specific clotting protein, called factor VIII (FVIII), due to mutations in the FVIII gene, while in hemophilia B it is caused by the lack of factor IX (FIX), due to mutations in the FIX gene.
This disorder, found almost exclusively in men, is normally treated with infusions containing the specific clotting proteins that patients are missing to prevent spontaneous bleeding episodes from occurring. But treatment is expensive, and in many countries can be scarce.
Researchers at McMaster University, North Carolina State University, Aix-Marseille University, and the University of Sheffield combined efforts to assess, for the first time, the prevalence of hemophilia in newborns at birth and its impact on life expectancy, as well as to estimate its prevalence on the worldwide male population.
The study was based on a meta-analysis performed using registry data of men living with hemophilia A or B in countries with comprehensive registries: Australia, Canada, France, Italy, New Zealand, and the United Kingdom.
According to their estimations, for every 100,000 men, 17 will have hemophilia A (the disease’s most common type) and four will have hemophilia B. Among these, six will have the most severe form of hemophilia A, and one will have the most severe form of hemophilia B.
Analysis of hemophilia’s prevalence birth indicated that for 100,000 male newborns, roughly 25 will have hemophilia A and 10 hemophilia B. Of these, five will be born with severe hemophilia A and two with severe hemophilia B.
Based on these findings, investigators came to the conclusion that about 1.125 million men worldwide are living with some form of hemophilia — three times higher than existing estimates, put at 400,000 by the National Hemophilia Foundation. Of these, 418,000 will have the disorder’s most severe forms and most of them will not receive a proper diagnosis or adequate treatment.
The impact of hemophilia on life expectancy was directly linked to the availability of medical care, the study found, and that care depended on each country’s economic status.
A life “disadvantage” expectancy of 64%, 77% and 93% was determined for patients living in upper-middle, lower-middle, and low-income countries, respectively. In high-income countries, the life expectancy disadvantage posed by hemophilia A was 30% (37% for the severe hemophilia A), and for hemophilia B was 24% (27% for severe hemophilia B).
“This paper is a milestone in our journey to providing care to hemophilia patients worldwide. Knowing how many patients are expected in each country given its population is an important measure of the efficiency of the health care system,” Alfonso Iorio, a professor of health research methods, evidence, and impact at McMaster University ,director of the Hamilton-Niagara hemophilia program at Hamilton Health Sciences, and the study’s lead author, said in a news release.
“Knowing how many patients should be there, and how many less are reported to national and international registries is a measure of the work left to be done,” Iorio added.
“The prevalence of hemophilia is higher than previously estimated” and patients “still have a life expectancy disadvantage,” the study concluded. “Establishing prevalence at birth is a milestone toward assessing years of life lost, years of life with disability, and burden of disease.”