Rapid response published today:
https://www.bmj.com/content/389/bmj.r977/rapid-responses
Lack of definition of cardinal features of ME/CFS, use of subjective outcomes, and bias in opinion piece
Dear Editor,
In their opinion piece, Miller, Symington, Garner, and Pedersen [1] do not define or acknowledge post exertional malaise (PEM) along with post-exertional symptom exacerbation (PESE) as the cardinal and unique features of ME/CFS (WHO, G93.3), differentiating this from chronic fatigue (CF, WHO, F48.0). Conflating the later with the former reduces the validity and therefore generalisability of their arguments.
Severe ME/CFS is defined by NICE (2021) [2] as: “People with severe ME/CFS are unable to do any activity for themselves or can carry out minimal daily tasks only (such as face washing or cleaning teeth). They have severe cognitive difficulties and may depend on a wheelchair for mobility. They are often unable to leave the house or have a severe and prolonged after-effect if they do so. They may also spend most of their time in bed and are often extremely sensitive to light and sound”.
What Severe ME has in common with wider, less reliable general concepts of the diagnostic category chronic fatigue is impossible to ascertain with any accuracy, clinician relevance or coherence.
The authors of the Leeds inpatient facility use subjective outcome measures to evaluate the effectiveness of their service. For example, the primary outcomes measure used is the Clinical Global Impression (Improvement) Scale - CGI-I. This “is established by consensus within the multidisciplinary team, at the point of discharge” (Leeds, 2021) [3], not by the patients. Further, there are no objective outcome measures used, for example, “….the unit is ideally placed to help patients re-engage in normal activities in the wider community as and when possible and appropriate.” The readers are not appraised of what objective, normal activities in the wider community patients were they able to do post admission. Were they, for example, able to return to work, study, caring responsibilities for children and grandchildren, to walk unaided, exercise, or self-care?
As the number of patients who completed further subjective questionnaires was only N=9, it is hard to draw any credible conclusions from the authors’ arguments from this small sample. The risk of expectation bias and placebo effect using such measures is high. These issues have been raised multiple times specifically in relation to ME/CFS (Journal of Health Psychology (2017) – Special issue on the PACE trial) [4].
Patients and clinicians need objective, real world evidence of consistent improvement and recovery rather than subjective opinions. This ensures that treatment approaches are supported by measurable outcomes which can effectively guide patient care and clinical practice. Thorough and systematic reviews by the IOM (2015) [5] and NICE (2021) [2] are clear that this objective, real world evidence does not currently exist.
It is incorrect for the authors to state, “the UK is following an outdated model, leading NICE to disallow cognitive approaches to help recovery or bespoke programmes designed to increase activity.” On the contrary, NICE (2021) [2] encourages supportive cognitive approaches as appropriate, depending upon the level of severity and highlights that the use of such should be personalised to the individual's needs and not based on the assumption that ME/CFS is caused by incorrect beliefs or behaviours, because that is an honest appraisal of the evidence base.
1. Miller, A; Symington, F; Garner, P; Pedersen, M. Patients with severe ME/CFS need hope and expert multidisciplinary care. BMJ 2025;389:r977. doi.org/10.1136/bmj.r977
2. NICE Guideline on ME/CFS: Diagnosis and Management [NG 206]. Oct 2021. Downloaded from,
https://www.nice.org.uk/guidance/NG206
3. Leeds and York Partnership NHS Foundation Trust. National Inpatient Centre for Psychological Medicine: annual review 2020-21. May 2021.
https://www.leedsandyorkpft.nhs.uk/our-services/wp-content/uploads/sites...
4. Marks DF. Special issue on the PACE Trial. Journal of Health Psychology. 2017;22(9):1103-1105. doi:10.1177/1359105317722370
5. Committee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome; Board on the Health of Select Populations; Institute of Medicine. Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness. Washington (DC): National Academies Press (US); 2015 Feb 10. PMID: 25695122.
Competing interests: No competing interests