Since it is May, Ehlers-Danlos Awareness month, I thought it might be good to explore just how common HSD and EDS are. Now, there is a reason I went into physical therapy and not mathematics – it is so easy to get lost in the numbers rather than have them tell a story. But let’s see what we can do. First a review.
Hypermobility spectrum disorder as well as all of the thirteen types of Ehlers-Danlos Syndromes are connective tissue disorders resulting in a constellation of problems first and foremost being hypermobile and painful joints. The earliest references to loose joints may have been by Hippocrates in 400 BC {2}. Diagnostic classifications for the connective tissue disorders have evolved over a long period of time.
Ehlers and Danlos were two physicians in the early 1900s. Edvard Lauritz Ehlers was a Danish Dermatologist who published a comprehensive report on patients with hypermobile joints and fragile elastic skin in 1901. And Henri-Alexandre Danlos was a French dermatologist who consulted on a patient diagnosed by Ehlers and gave a contrasting opinion. {2}
The effort to classify the disorders as they are now diagnosed began in 2012 with the formation of an international consortium of experts which published the current diagnostic criteria in the American Journal of Medical Genetics in 2017 {2}. That was only six years ago.
When trying to determine how common any diagnosis is in the population, the specifics of how that diagnosis is made are very important. In other words, how you define something very much affects how it is counted. Before 2017, rather than classifying Hypermobility Spectrum disorder and Hypermobile Ehlers Danlos Syndrome separately, they were lumped together into one category: joint hypermobility syndrome {1}. So, as you might expect, the conversation about how common HSD, hEDS and each of the twelve other types of EDS are, is an ongoing one.
So, are HSD and EDS common? I have translated the diagram provided by the EDS Society {1}, which gives the best recent estimates of case numbers, into the table below and added a column. Since we are talking about cases per million, and since the population of the US in 2021 was 332,278,200 (according to Siri), the column at the right estimates how many cases there may be in the US.
| Condition | Estimated Cases per 1 Million People | Estimated Cases in the US |
| All EDS and HSD | 2000 | 664,556 |
| hEDS and HSD Only | 1900 | 631,329 |
| hEDS | 320 | 106,329 |
| Classical EDS | 50 | 16,614 |
| Vascular EDS | 10 | 3,323 |
| Other Types of EDS: Arthrocalasia Brittle Cornea Syndrome Classical-Like EDS Dermatospraxis Kyphoscoliotic EDS Musculocontractural EDS Myopathic EDS Periodontal EDS Spondylodysplastic EDS | Less than 1 | 332 |
A condition is thought to be rare if it affects less than 1 person in 2,000 which is the same as 500 in a million. As you can see above then, all of EDS types combined and also HSD combined with hEDS are not rare, but each of the other categories of EDS would be considered rare. This assumes that the studies are getting an accurate estimate of numbers. And that is a big assumption. As more doctors learn how to diagnose these conditions, these numbers may change.
We are still thinking about what to write about next in this blog series. Future topics may include mindfulness, digestive issues in HSD and hEDS and others.
Until then, cheers!
Zebbie
Zeborah Dazzle, PT, WWF
Spokes-Zebra and Patient Educator for Good Health Physical Therapy and Wellness.
Thanks to Dr. Mark Melecki, PT for his assistance in preparing this blog. (It is very challenging to type with hooves rather than fingers. Thanks Mark.)
References:
- Ehlers-Danlos Society, Are the Ehlers-Danlos and Hypermobility Spectrum Disorders Rare or common? https://www.ehlers-danlos.com/is-eds-rare-or-common/ 2023
- Stott, P., Purdin, H., Introduction to HSD/EDS: Course Notes. Medbridge Online continuing Education. https://www.medbridgeeducation.com/sign-in 2022
- Demmler, JC, 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.
