The incidence of Ehlers-Danlos syndromes (EDS) and hypermobility spectrum disorders (HSD)
Our community may read several comments regarding the prevalence rates of EDS and HSD. We hope the following is a useful summary.
What makes a condition 'rare'?
A condition is considered rare if it affects fewer than 1 in 2,000 people. Numbers can be presented in different ways, but they mean the same thing. For example, a document may state that 5 per 10,000 people or less than 50 per 100,000 is rare.
Statements on the prevalence of Ehlers-Danlos syndromes
Ofoverall distributionof Ehlers-Danlos syndrome (EDS) is quoted as 1 in 5000, based on a publication by Pyeritz (2000), and further supported by population data from Denmark (Kulas Søborg et al., 2017) and data extrapolated from a Swedish study (Cederlöf et al., 2016). In a study of health records in the Welsh population, Demmler et al. (2019) found an EDS prevalence of approximately 1 in 3100. However, as more is learned about the most common type of EDS, hypermobile EDS (hEDS), it is now believed that the incidence figures for hEDS are an underestimate. Population studies to clearly demonstrate this still need to be done. This is further explained in the section below on joint hypermobility syndrome (JHS), hEDS and hypermobility spectrum disorder (HSD).
Besides hEDS, the other types of EDS are rarer than 1 in 5000. Classical EDS has a prevalence of 1 in 20,000-40,000. Vascular EDS has a prevalence of 1 in 100,000-200,000. Other types of EDS affect fewer than 1 in a million or are extremely rare and affect a small number of individuals and families (Malfait et al., 2017).
At The Ehlers-Danlos Society, we believe that regardless of how prevalence rates are discussed, it should always be clear which type or types of EDS are being considered. Use a figure for thisoverall distributionor a combined prevalence masks the fact that different types of EDS have different prevalence rates. For the avoidance of doubt, we would like to see a shift from general/combined prevalence statements to statements that are explicit about the type of EDS being discussed. We believe that this should also apply to studies and commentaries on HSD.
What do we know about the prevalence of joint hypermobility syndrome and how is this relevant to hypermobility spectrum disorders and hypermobile Ehlers-Danlos syndrome based on the 2017 criteria?
Two large population studies examined the prevalence of joint hypermobility syndrome (JHS) and Ehlers-Danlos syndrome (EDS). The prevalence of these conditions was specifically examined (Demmler et al., 2019); the other looked at mental health and neurodiversity, but the data can be used to determine the prevalence of JHS and EDS (Cederlöf et al., 2016). A third study also provides insight into the prevalence of JHS by extrapolating observations from rheumatology clinics in Great Britain (Hakim & Grahame, 2006).
These studies showed similar results, with the total/combined prevalence of JHS and EDS ranging from 1 in 500 to 1 in 800. However, when broken down into JHS or EDS, the studies found that:
· the prevalence of JHS was approx. 1 in 600 to 1 in 900, and
· the prevalence of all types of EDS was approx. 1 in 3000 to 1 in 5000.
JHS was found to be five times more common than EDS.
After 2017, the JHS designation was deleted. Instead, this community population is now described as having hypermobility spectrum disorder (HSD) or hypermobile EDS (hEDS), based on the 2017 International Criteria for hEDS and descriptors for HSD. Prevalence rates for JHS are now used to describe the combined prevalence of HSD and hEDS. The combined prevalence of HSD and hEDS is in the range of 1 in 600 to 1 in 900. Expert opinion is that HSD is common and that hEDS is probably common. However, at this time it is not possible to say what the prevalence is for both HSD and hEDS separately, as this has not yet been studied.
Experts also believe that all of these prevalence figures are an underestimate because many people with EDS or HSD go undiagnosed, take years to diagnose, or are misdiagnosed with another condition.
Knowing prevalence affects how health care resources are allocated.
When providing healthcare resources, knowing whether a condition is rare or common is equally important for several reasons.
It is important to recognize that most types of EDS are rare or ultra-rare. Healthcare services and organizations that fund healthcare research are making specific decisions about how to support people with rare conditions. It remains extremely important to recognize that within the EDS family there are types of EDS that benefit from the resources available for rare diseases.
But just as importantly, if the entire family of these conditions, including hEDS and HSD, are thought to be rare, health professionals, healthcare organizations and policy makers may think that hEDS and HSD are not relevant to them. Priority is given to common conditions that affect multiple people.
Expert opinion is that HSD is common. The incidence of hEDS is now believed to be greater than previously described, but by how much is not yet clear. Healthcare professionals and organizations who are unaware that they are likely to see people with HSD or hEDS risk missing diagnoses, not knowing how to care for people with these disorders, and not having the resources to be cared for by them. For too many in our society, this is not an imaginary condition; it is a lived experience (Halverson et al., 2021).
In summary
At Ehlers-Danlos Selskabet we believe that EDS and HSD are two of the most misunderstood conditions of our time. We and many expert physicians believe that HSD and hypermobile EDS (hEDS) are more common than currently recognized. However, it is also important to remember that most types of EDS are rare to extremely rare.
We know how important it is to raise awareness about HSD and EDS. We are committed to our mission to increase education, support, and research in all types of EDS and HSD. Access to early diagnosis, treatment, care and validation is at the heart of what we do, and we want to ensure that the wider medical community gives these conditions the respect and understanding they deserve.
Finally in 2021. Hakim, Tinkle and Francomano wrote the following in an editorial for the American Journal of Medical Genetics, which we think sums it up for us:
“In both community care and a wide range of hospital specialties, many health professionals (nurses, midwives, physiotherapists and other therapists, psychologists and doctors) are likely to care for people with Ehlers-Danlos syndrome (EDS) or hypermobility spectrum disorders. HSD). The belief that EDS is rare or ultra-rare applies to several forms of the syndrome, but it is increasingly believed that the hypermobile type of EDS (hEDS) is more common, and HSD is much more common. The journey to diagnosis and treatment is often challenging for patients who are undiagnosed or misdiagnosed. Furthermore, it is often reported that the problems are purely psychological in nature. All too often there is a delay of more than ten years in diagnosis, and the quality of life with an undertreated disease is significant.…
With the significant growth of knowledge in this field, it is challenging to keep abreast of advances in the epidemiology, pathophysiology, and management of this heterogeneous group of disorders. No individual healthcare provider can truly address all aspects of these conditions at an expert level. Care generally requires a holistic and interdisciplinary approach. Yet such care, ideally embedded in the community, supported by subspecialized medical, therapeutic and social care for EDS and HSD is lacking internationally. Currently there are a small number of specialist clinics, centers and networks that aim to support patients and colleagues. Access to care is severely limited, but management of many of the common problems is within the capabilities of most generalists, with specialist support as needed.”
