Are the Ehlers-Danlos Syndromes and Hypermobility Spectrum Disorders Rare or Common?

What is the prevalence of the Ehlers-Danlos syndromes and hypermobility spectrum disorders? 

The overall prevalence of Ehlers-Danlos syndromes (EDS), is considered to be 1 in 5000 (Pyeritz, 2000) which is considered to be rare around the world. Several variants of EDS are rarer than that with prevalence figures of 1 in 20,000 to 1 in 100,000, or ultra-rare, affecting small numbers of individuals and families (Malfait et al., 2017).  

The population prevalence of the hypermobility spectrum disorders (HSD) and the most common variant of EDS, hypermobile EDS (hEDS) is not known. Conclusions can be made from national healthcare records studies that the prevalence of hEDS is of the order 1 in 3500 to 1 in 5000 (Cederlöf et al., 2016, Kulas Søborg et al., 2017, Demmler et al., 2019). However, this data would not include those who have either not presented to a doctor with the condition or in whom the diagnosis has been missed, making the true prevalence likely to be greater.  

In November 2019 a paper by Demmler et al. was published looking at patient records from healthcare service databases in Wales over 27 years up to 2017. The study reported that either the diagnosis Ehlers-Danlos syndrome (EDS) or Joint Hypermobility Syndrome (JHS) was found in the healthcare General Practice or Hospital records of around 1 in 500 people in Wales. It concluded that EDS/HSD are not rare conditions. What the data actually showed was that the medical record prevalence for JHS was approx. 1 in 600 (a figure similar to that extrapolated in a communication by Grahame and Hakim, 2006), and that the overall prevalence for all types of EDS was approx. 1 in 3200. 

We completely support research that highlights the prevalence and complexity of the conditions that affect our community. The Ehlers-Danlos Society is, nevertheless, concerned that this paper has led to public opinion that the Ehlers-Danlos syndromes (all subtypes combined) are common, when this has not actually been demonstrated. The term “EDS” indicates all types of EDS, and not only hypermobile EDS (hEDS). Leading clinicians in the field have written to the British Medical Journal expressing concern about the methodology and terminology used. This letter can be read on the BMJ website here. 

We believe that hEDS and HSD are two of the most mis-understood conditions of our time, and we look forward to a time when robust research with clean phenotyped data can show that both hEDS and HSD are common, as we believe, anecdotally, them to be. However, it is important to remember that there are at present 14 types of EDS, and that internationally it is acknowledged that (for all but hEDS, for which the answer remains unclear) these are rare to ultra-rare conditions.  

We would like to reassure our community there is no benefit to our organisation in saying that the Ehlers-Danlos syndromes are rare. If it was found to be the case that they are common we would absolutely embrace this. We have never received funding for Rare Diseases since our launch in 2016. We are aware however that healthcare services and health research funding organisations, for example, make decisions about how they support people with rare conditions like those in our community. To lose that support based on a mis-conception is not right, given it is internationally acknowledged that conditions within the EDS family are rare.  

Equally, we know it is so important to raise awareness about HSD and hEDS. We have never stopped, nor will we ever stop doing this. We live and breathe this. We are committed to our mission to increase education, support and research into all types of EDS and HSD equally. Access to early diagnosis, management, care and validation is at the heart of what we do, and we want to ensure that the wider medical community give these conditions the respect and understanding they deserve. A key way to ensure this is through research and review publications that accurately describe current knowledge.

We believe that all types of EDS and HSD continue to be mis and underdiagnosed, but this does not make them common. Determining the true prevalence of HSD, hEDS, and the more rare subtypes of EDS remains a research priority for The Society.

Cederlöf M, Larsson H, Lichtenstein P, et al. Nationwide population-based cohort study of psychiatric disorders in individuals with Ehlers-Danlos syndrome or hypermobility syndrome and their siblings. BMC Psychiatry. 2016 Jul 4;16:207. doi: 10.1186/s12888-016-0922-6. 

Demmler JC, Atkinson MD, Reinhold EJ, et al Diagnosed prevalence of Ehlers-Danlos syndrome and hypermobility spectrum disorder in Wales, UK: a national electronic cohort study and case–control comparison BMJ Open 2019;9:e031365. doi:10.1136/bmjopen-2019-031365. 

GRAHAME R, HAKIM AJ. Joint Hypermobility Syndrome is highly prevalent in general rheumatology clinics, its occurrence and clinical presentation being gender, age, and race- related. Ann Rheum Dis 2006; 65:263 

Kulas Søborg M-L, Leganger J, Quitzau Mortensen L, et al. Establishment and baseline characteristics of a nationwide Danish cohort of patients with Ehlers-Danlos syndrome. Rheumatology (Oxford). 2017 May 1;56(5):763-767.

Malfait F, Francomano C, Byers P, et al. The 2017 international classification of the Ehlers-Danlos syndromes. Am J Med Genet C Semin Med Genet. 2017 Mar;175(1):8-26. 

Pyeritz RE. Ehlers-Danlos syndromes. N Engl J Med 2000; 342:730-732. 

This week a paper by Demmler et al. has been published that looks at patient records from healthcare service databases in Wales over 27 years up to 2017. The study reports that either the diagnosis Ehlers-Danlos syndrome (EDS) or Joint Hypermobility Syndrome (JHS) was found in the healthcare General Practice or Hospital records of around 1 in 500 people in Wales. It concludes that EDS/HSD are not rare conditions. 

The Ehlers-Danlos Society is of the opinion that this is an incorrect conclusion. It is essential that the correct terminology is used to describe what has been studied, in order to avoid confusing, misleading, and potentially harmful statements. We will be writing to the British Medical Journal with our concerns. 

First, based on the methodology, it is misleading to combine EDS and JHS; they are not the same conditions. 

Second, the authors move seamlessly from a discussion about JHS and EDS to applying their observations to the post 2017 criteria terminology of HSD/hEDS. The authors propose that “this suggests that hEDS/HSD, when considered together, do not meet the definition of rare conditions.” It is not clear, nor would we imagine it to be possible from the source data, how many with JHS might now be determined as having HSD, or having hEDS under the new classification. In order to calculate the prevalence of hEDS the authors would need to know this. 

Finally, unfortunately the authors “conclude that EDS/HSD are not rare conditions”. Again, they have combined EDS and HSD in the way they did EDS and JHS, leading to the same error. 

In our opinion the correct presentation of the data should be a population prevalence for JHS and a separate population prevalence for ‘all types’ EDS. How many of these individuals with JHS might have a more HSD-like form of JHS and how many a more hEDS-like form of JHS will not be known unless this population is re-assessed. The flow diagram below aims to describe this concern:

At this time the evidence still suggests that EDS is rare. Until such time that studies separate JHS from EDS 3 / EDS hypermobile type in the old terminology, or HSD and hEDS in the new, the prevalence of hEDS remains unclear. The understanding that the condition JHS is not rare is not new; JHS has never been thought of as a rare condition among the contributors to the literature. This paper would at least seem to validate that. 

It is important to realize that many of the subtypes of EDS are very rare. This has significant impact in many ways, including the need to establish international collaborative basic science and clinical research networks, patient and family support networks, and sub-specialty and specific diagnostic and management pathways. 

The Society is committed to supporting research that determines the true prevalence of HSD, hEDS, and the more rare subtypes of EDS, but with regard to prevalence we do not support the misleading conclusions in this paper. 

Alan Hakim, MA, FRCP and Fransiska Malfait, MD, PhD 

Chief Medical Officer and Chief Scientific Officer, The Ehlers-Danlos Society