Prevalence of ME/CFS in England – roughly 2 in 1,000 primary care patients ages 18-64

Prevalence of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) in three regions of England: A repeated cross-sectional study in primary care – Source: BMC Medicine, Jul 28, 2011

By Luis C Nacul, et al.

[Note: The research reported here was conducted in 2010, so did not address prevalence of cases according to the International Consensus Criteria (ICC) for diagnosis of Myalgic Encephalomyelitis, published in July 2011. But this study did calculate prevalence according to the Canadian Consensus Criteria, which influenced the ICC. Overall, prevalence was higher in women, varied by area and among the different sets of diagnostic criteria used; but average incidence according to any set of criteria considered was 2 in 1,000 primary care patients ages 18-64. To read the full text pdf of this article, click here –]


Background: ME/CFS or chronic fatigue syndrome (CFS) has been used to name a range of chronic conditions characterized by extreme fatigue and other disabling symptoms. Attempts to estimate the burden of disease have been limited by selection bias, and by lack of diagnostic biomarkers and of agreed reproducible case definitions.

We estimated the prevalence and incidence of ME/CFS in three regions in England, and discussed the implications of frequency statistics and the use of different case definitions for health and social care planning and for research.

Methods: We compared the clinical presentation, prevalence and incidence of ME/CFS based in a sample of 143,000 individuals aged 18 to 64 years, covered by primary care services in 3 regions of England.

Case ascertainment involved:

1. Electronic search for chronic fatigue cases;

2. Direct questioning of general practitioners (GPs) on cases not previously identified by the search;

3. Clinical review of identified cases according to:

• CDC-1994,

• Canadian

• And Epidemiological Case (ECD) Definitions.

This enabled the identification of cases with high validity.

Results: The estimated minimum prevalence rate of ME/CFS was:

• 0.2% [2 cases per 1,000 primary care patients ages 18-64] for cases meeting any of the study case definitions,

• 0.19% for the CDC-1994 definition [1.9 cases per 1,000],

• 0.11% for the Canadian definition [1.1 cases per 1,000]

• And 0.03% for the ECD [0.3 cases per 1,000].

The overall estimated minimal yearly incidence was 0.015% [minimum risk of ME/CFS in a given year, 1.5 cases in 10,000].

The highest rates were found in London and the lowest in East Yorkshire.

All cases conforming to the Canadian criteria also met the CDC-1994 criteria but presented higher prevalence and severity of symptoms.


• 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.

• We suggest combining the use of both the CDC-1994 and Canadian criteria for ascertainment of ME/CFS cases, alongside careful clinical phenotyping of study participants.

This combination if used systematically will enable international comparisons, minimization of bias, and the identification and investigation of distinct sub-groups of patients with possibly distinct aetiologies and pathophysiologies, standing a better chance of translation into effective specific treatments.

Source: BMC Medicine, Jul 28, 2011;9(91). DOI:10.1186/1741-7015-9-91, by Nacul LC, Lacerda EM, Pheby d, Campion P, Molokhia M, Fayyaz s, Leite JCDC, Poland F, Howe A, Drachler ML. Department of Nutrition and Public Health Interventions Research, London School of Hygiene and Tropical Medicine, London; Foundation for Genomics and Population Health, Cambridge; National ME Observatory Project & Bucks New University, High Wycombe, Buckinghamshire; Hull-York Medical School, University of Hull, Hull; Department of Primary Care and Public Health Sciences, Division of Health and Social Care Research. Kings College, London; University of East Anglia, Norwich, UK. [Email:]

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