Prevalence of ME/CFS in the UK

Prevalence is the number of people in a population who have a certain disease at a given time or over a specified period of time.

Considering the factors that influence the prevalence of a disease:

Incidence – the number of new cases of a disease,
Recovery rate – the number of people recovering from the disease,
Migration – the number of people with the disease leaving the specified area, and
Mortality rate – the number of deaths occurring in those with a disease.

it is unlikely that the prevalence of ME/CFS has decreased significantly over time. This is because ME/CFS is a chronic disease that usually persists over a long period of time – with no known cure, or approved treatment – meaning the recovery rate is low. It is also thought that the mortality rate for the disease is also relatively low, although an increase of death at an earlier age (earlier mortality) has been observed for people with ME/CFS.

Rather, research suggests that prevalence of ME/CFS has increased due to:

An increase in the numbers of people meeting ME/CFS diagnostic criteria following long COVID.
An increase in awareness of ME/CFS through long COVID improving rates of diagnosis – and also potentially following the publication of the 2021 NICE guidelines.

What the evidence tells us so far

The most recent government reports suggest that:

“250,000 people have ME/CFS in the UK” (2021 NICE guidelines for ME/CFS)
“Around 20,000 people in Scotland are living with the condition (ME/CFS)” (report from the Scottish Government, 2022)
“There are more than 7,000 cases (of ME/CFS) in Northern Ireland” (Position Statement 2016)

The most recent peer-reviewed research on ME/CFS prevalence in the UK suggests a rate of 0.448%. This figure was published in 2018 based on self-reported ME/CFS using data from the UK Biobank – a sample of people from the UK. Notably, this prevalence rate is the basis for the 250,000 figure cited in the 2021 NICE guidelines. However, there are limitations including that the estimate is based on information that does not reflect the UK population as a whole; for example, the UK Biobank only includes data from those aged 40-69 years of age.

There are no systematic reviews – studies that use repeatable methods to search for, select, and combine all available evidence to answer a specific research question – relating to the prevalence of ME/CFS in the UK, and there has been only one comprehensive systematic review of the worldwide prevalence of ME/CFS which was published in 2020.

Within this systematic review, although several studies considered the prevalence of ME/CFS in the UK – with estimates ranging from 0.1% to 2.62% – all were published before the 2018 UK Biobank study referenced by the 2021 NICE guidelines.

Additionally, in a systematic review published in 2020, an overall prevalence estimate for Europe was given as 0.1% to 2.2%, but this was based on three studies published between 2002 and 2011.

Since these studies were published, evidence from the UK and the USA supports an increase in ME/CFS prevalence following the COVID-19 pandemic:

In England, a pre-print study, which is published ahead of peer review, considered hospital data from before and during the pandemic; 62,782,175 people with a valid NHS number in “England” between April 1, 1989, and October 7, 2023. This study found that 0.16% (100,055 of 62,782,175 people) had a record of the diagnostic code for “post-viral fatigue” – a coding that encompasses, but is not limited to ME/CFS.
- The researchers also attempted to take into consideration low rates of diagnosis for ME/CFS and found that when considering the places in England with the highest rates of diagnosis for “post-viral fatigue”, prevalence could be estimated as 0.585%.
  - This suggested that based on the UK population size in 2022 of 67 million, there would be 391,950 people diagnosed with “post-viral fatigue syndrome” which includes ME/CFS.
    - This value is an increase from previous estimates of 250,000 people in England and Wales, 20,000 in Scotland, and 7,000 in Northern Ireland – a total of 277,000).

Estimates from the USA also suggest that there has been an increase in ME/CFS following the COVID-19 pandemic to approximately 1.3%. However, these estimates are based on self-reported prevalence of ME/CFS.
- Additional calculations from Mirin and Jason also support this post-COVID increase finding that following the COVID-19 pandemic, the prevalence of “ME/CFS” in the USA may have increased from 1.49 million using existing estimates of ME/CFS to between “5 and 9 million individuals”.

Interestingly, larger numbers for the prevalence of ME/CFS in the UK have also been cited – for example, in July 2024 – at the inquest of Maeve Boothby-O’Neil, Professor David Strain stated that there are around 750,000 people in the UK. However, it is unclear which research this estimate is based upon, or how this number has been calculated. It appears that the number may have been extracted from a rapid response in the BMJ relating to ongoing symptoms following COVID which states that: “It is estimated there are currently at least 750,000 individuals in the UK with persistent symptoms for more than 2 years (and hence become a long-term condition)”. Additionally in Westminster Hall during a 2024 debate on ME/CFS it was mentioned that “… 1.3 million people live with ME or ME-like symptoms..” Although, again, it is unclear where this estimate has come from.

What conclusions can be drawn?

Due to the long-term nature of ME/CFS, the prevalence of the disease is very unlikely to have decreased. Therefore, it is highly likely that there are more than 250,000 people (based on a prevalence rate of 0.448%) with ME/CFS in the UK.

If the prevalence rate of 0.448% is applied to the more recent UK population size of 68,265,200 in 2023, this would equate to 305,828 people. It is important to note that this increase only captures the impact of population growth over time on the prevalence of ME/CFS, and not actual changes in prevalence which may have occurred for example, due to the COVID-19 pandemic.

Existing prevalence estimates for the UK range from 0.1% to 2.6% – if this range was applied to the most recent population estimate for the UK – 68,265,200 in 2023, these rates would translate to between approx. 68,265 and 1,774,895 people. Notably, this includes the most recent estimate – from the pre-print study by Samms and Ponting, of 390,195 people with ME/CFS (or 0.585%; which if applied to the more recent UK population size of 68,265,200 in 2023, equates to 399,351 people).

While evidence does suggest that it is highly likely there are more than 250,000 people with ME/CFS in the UK, research has yet to provide a universally acceptable answer on the prevalence of ME/CFS in the UK in 2024.

What are the next steps?

Obtaining an accurate estimate for the prevalence of ME/CFS in the UK – or elsewhere in the world – is a highly complex task, and one that a single research team alone would likely be unable to solve.

Rather it is possible that multi-disciplinary collaboration is required, and that the best next step could be to conduct a roundtable discussion with experts in the field including:

ME/CFS researchers.
Methodological and statistical experts.
Clinicians who work with and diagnose those with ME/CFS.
Representatives from ME/CFS charities.
Royal Colleges.
Those with lived experience of ME/CFS.
Representatives from the UK’s various NHS to ensure more precise and consistent coding of ME/CFS.

Within this discussion, it would be important to:

Establish whether it is possible to obtain a more accurate estimate for the prevalence of ME/CFS than those which already exist. If the group does think it is possible.
- Specify the methodology that could be used to obtain such an estimate – especially how people with ME/CFS would be identified accurately.
- Estimate what the cost of such a project would be – and consider whether this cost would be worth the additional knowledge.
  - For example; to establish the change which would occur if a large amount of money was spent on obtaining a more accurate estimate for the prevalence of ME/CFS in the UK, for example, would more government funding be allocated to research into the disease.
To gain consensus as to where an accurate estimate for the prevalence of ME/CFS falls into existing research priorities for ME/CFS in 2024 given that the prevalence of ME/CFS was not among 2021 NICE Recommendations for research nor the top 10 James Lind Alliance Priority Setting Partnerships in 2022, the 2002 CMO report stated that:

“Little more is known about the incidence and prevalence of CFS/ME. As a result, a key piece of information is missing – one that is needed in order to undertake health-needs assessment as a prelude to provision of an adequate network of services. This gap needs to be filled if the NHS and other agencies are to meet the needs of these patients in a comprehensive and equitable way.”