Medical Matters > Prevalance: Population Estimates

ME Essential Spring 2021


The MEA always uses a figure of around 250,000 when you refer to the number of people in the UK who have ME/CFS. But where does that figure come from? And how accurate is it?


The simple answer to your question is that we just don’t know how many people have ME/CFS. This is because there is no accurate notification system in the NHS that records the number of people who have ME/CFS in each GP practice and no large epidemiological research study has been carried out to estimate the prevalence of ME/CFS. So we make an estimate based on what little evidence there is from the small number of epidemiological research studies that have been completed in the UK and overseas.

Information about actual numbers of people with ME/CFS is also hampered because of the disagreements and difficulties as to how we define the illness. And the use of the restrictive definitions of ME/CFS that are used for research purposes mean that estimates are likely to underrepresent the true scale of the disease, particularly the number of people with severe ME/CFS.

One UK study  from Dr Nacul and the ME/CFS Biobank team, concluded:

The estimated minimum prevalence rate of ME/CFS was 0.2% for cases meeting any of the study case definitions, 0.19% for the CDC-1994 definition, 0.11% for the Canadian definition and 0.03% for the ECD. The overall estimated minimal yearly incidence was 0.015%.

ME/CFS is not uncommon in England and represents a significant burden to patients and society. The number of people with chronic fatigue who do not meet specific criteria for ME/CFS is higher still. Both groups have high levels of need for service provision, including health and social care.

Overall, the current evidence suggests:

  • A population prevalence of at least 0.2% – 0.4% (i.e., 2 to 4 per 1000 people).
  • A minum yearly incidence has been suggested of 0.015%.
  • The commonest age of onset is early twenties to mid-forties.
  • In children, the commonest age of onset is 13–15, but cases can occur as young as five years old.
  • ME/CFS is roughly three times as common in women as it is in men.
  • It affects all socio-economic classes to a similar extent.
  • It affects all ethnic groups – although it is believed to be under-diagnosed in ethnic minority groups.

This lack of epidemiological research means that a vital piece of information is missing which is needed in order to undertake the sort of health-needs assessment that underpins the funding and provision of an adequate network of healthcare services. This is a gap that needs to be filled if the NHS and other agencies are going to meet the needs of people with ME/CFS in a comprehensive and equitable way, and it would help to underpin the need for effective implementation of the 2021 NICE Clinical Guideline.

In the UK, the organisation of primary (GP) care services creates a unique opportunity to conduct prevalence studies on a scale necessary to provide this much-needed information. However, this is costly research to carry out and not something that the ME Association Ramsay Research Fund could afford. So we really need some government-funded research to fill this very important gap in our knowledge about ME/CFS.

More information:

  • We consider prevalance and what to expect from a diagnosis of ME/CFS in terms of disability, improvement, recovery, and quality of life, based on research evidence and expert medical opinion in a detailed booklet available to download from the website shop.
  • The epidemiological research studies upon which we base our often-used prevalence estimate of between 250-265,000 affected people in the UK are also summarised and referenced in Epidemiology chapter in the ME Association's ME/CFS/PVFS Clinical & Research Guide (The ‘Purple Book').


Information provided by The ME Association should not be construed as medical advice. Don't assume any new or worsened symptoms are simply the result of having ME/CFS or Long Covid. We recommend that any information you deem relevant is discussed with your NHS GP as soon as possible. It is important that you seek personalised medical advice from the GP who is in charge of your care and who knows you well.

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