Occurrence Rates of von Willebrand Disease Among People Receiving Care in Specialized Treatment Centers in the United States
Von Willebrand disease (VWD) is a blood disorder in which the blood does not clot properly. Blood contains many proteins that help the body stop bleeding. One of these proteins is called von Willebrand factor (VWF). People with VWD either have a low level of VWF in their blood or the VWF protein doesn’t work the way it should. There are three types of VWD: type 1 (the most common and mildest form of VWD), type 2, and type 3 (the most severe form of VWD).
Most people who have VWD are born with it. It is almost always inherited, or passed down, from a parent to a child. VWD can be passed down from either the mother or the father, or both, to the child. While rare, it is possible for a person to get VWD without having any family members who have had (family history) the disease.
VWD is the most common inherited bleeding disorder. Previous research has found that it occurs among men and women equally; however, women are more likely to notice the symptoms because of heavy or abnormal bleeding during their menstrual periods and after childbirth. Identifying how many people in the United States have VWD can be helpful in understanding the healthcare needs of those living with VWD and aid in healthcare planning.
Prevalence is a statistical concept referring to the number of people (existing cases) who have a disease or medical condition at a particular time. Incidence refers to the number of new people (new cases) born with a disease or medical condition during a particular time period.
About This Study
Researchers from CDC and the U.S. Hemophilia Treatment Center Network (USHTCN) carried out a study using information collected from a public health monitoring program called Community Counts. This program gathers and shares information about common health issues, medical complications, and causes of death that affect people with bleeding disorders cared for in federally supported U.S. Hemophilia Treatment Centers (HTCs). The researchers report study findings from 23,479 men and women with VWD who received treatment at a federally supported HTC between 2012–2019. The goals of the study were to:
- Estimate the prevalence of VWD based on men and women receiving care at HTCs
- Estimate the incidence of VWD based on men and women receiving care at HTCs
In any study, the number of people in different age groups will vary. For example, let’s say that most people in city A are between the ages of 25-45, but most people in city B are between the ages of 55-75. This can make it hard to compare health characteristics between people living in the two cities because some health problems are more common among older people. Age-adjusting is a statistical method that helps researchers ensure that differences between groups are not due to their age distributions.
- VWD Prevalence and Incidence
- The most common type of VWD among both men and women was type 1 (average age-adjusted rate of 8.5 cases per 100,000 people) and the rarest type of VWD was type 3 (average age-adjusted rate of 2 cases per 1 million people).
- Among both men and women, the average age-adjusted incidence of VWD type 1 was 17.8 cases per 100,000 people born.
- Differences Between Men and Women
- Across all types of VWD, there were more cases among women than men (5.6 cases vs. 3 cases per 100,000 people).
- Among those with type 1 VWD, there were twice as many cases among women than men (4.8 cases vs. 2.4 cases per 100,000 people).
- During the study period, the number of new cases of type 1 VWD among women was nearly three times higher than that among men (2 vs. 9.9 per 100,000 people born).
- Among the participants in this study with type 1 VWD, most were young boys ages 5-14 years and young women and girls ages 10-24 years.
Critical Gaps & Future Directions
Several observations from this study need further research:
- This study included people who received treatment for VWD at federally supported HTCs between 2012–2019. Not all people with VWD receive treatment for their condition, and many may receive treatment at healthcare centers other than HTCs; therefore, more research is needed to find out how many people have VWD in the U.S. that were not included in this study.
- There were more women with type 1 VWD than men in this study, and most cases of type 1 VWD were observed at a later age among women than among men. This observation could be because women experience bleeding symptoms more often due to menstruation (monthly periods) and childbirth, and therefore, may seek care and treatment.
- More work is needed to get a better idea of how many people use sources other than HTCs for their care. It is also important to know whether the treatment and health of people with VWD seen in HTCs differ from that of people with VWD who are seen outside of the HTC system.
Please visit the following links for more information:
Soucie JM, Miller CH, Byams VB, Payne AB, Abe K, Sidonio RF Jr, et al. Occurrence rates of von Willebrand disease among people receiving care in specialized treatment centers in the United States. Haemophilia 2021. https://doi.org/10.1111/hae.14263external icon [ePub ahead of print]