In 2015, the Institute of Medicine (IOM), now the National Academy of Medicine (NAM), published clinical criteria for diagnosing ME/CFS. According to the committee responsible, these criteria “focus more on the central symptoms of this disease than many other definitions” yet “are quite similar to the Canadian Consensus Criteria (CCC).” The committee also acknowledged that individuals diagnosed with other criteria, such as Fukuda, may not meet the proposed requirements, nevertheless “should receive appropriate care.”
Note: The committee recommended that ME/CFS be renamed to systemic exertion intolerance disease (SEID) as it “captures the fact that exertion of any sort—physical, cognitive, emotional—can adversely affect these patients in many organ systems and in many aspects of their lives.” However, the name was not adopted, rather the CDC continues to refer to the disease as ME/CFS when making reference to the IOM criteria.
Summary of IOM 2015 Criteria
All of the following must be present –
- A substantial reduction or impairment in ability to engage in pre-illness levels of activity (related to occupational, educational, social, or personal activities) that –
- Persists more than 6 months
- Is accompanied by fatigue, which is often profound, of new or definite onset, not due to ongoing excessive exertion, and not substantially alleviated by rest
- Post-exertional malaise (PEM)
(a prolonged worsening of baseline symptoms, following physical, cognitive, or orthostatic stress, which may be delayed relative to the trigger) - Unrefreshing sleep
(feeling unrefreshed despite substantial sleep, and other sleep disorders)
At least one of the following must be present –
- Cognitive impairment
(problems with thinking “exacerbated by exertion, effort, or stress or time pressure”) - Orthostatic intolerance
(“Symptoms worsen upon assuming and maintaining upright posture” and improve, though are “not necessarily abolished”, by lying down)
*In relation to PEM, unrefreshing sleep and cognitive impairment, “diagnosis of ME/CFS should be questioned if patients do not have these symptoms at least half of the time with moderate, substantial, or severe intensity.”
Considerations
Criticism of the IOM criteria includes –
- Name change
The proposal to rename ME/CFS to SEID faced backlash from the patient community. This reaction was predicted by Dr Leonard Jason in an interview with David Tuller, where he stated – “The committee has come up with a name without vetting it. And they will basically get a tremendous amount of discontent and dissatisfaction right from the starting point, because the patients want something very different.” Many individuals felt that the term SEID failed to capture the complexity of the illness and minimised its severity.
- Broadness and overdiagnosis
There have been concerns that the IOM criteria could, by requiring only four symptoms for diagnosis and having “ambiguity” around exclusionary conditions, lead to overdiagnosis compared to previous case definitions, e.g. Fukuda.
The NICE 2021 criteria also require four symptoms, but unlike the IOM criteria, they do not allow orthostatic intolerance to substitute for cognitive dysfunction. It should also be noted that the Fukuda criteria do not require PEM – now considered a hallmark of ME/CFS – whereas both the IOM and NICE criteria do. - Severity
While the IOM criteria acknowledge severity levels and suggest external resources for symptom assessment, they do not provide a standardised severity classification. This lack of specificity may result in inconsistencies in diagnosis between clinicians.
Reference:
National Academies of Sciences, Engineering, and Medicine. 2015. Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness. Washington, DC: The National Academies Press. https://doi.org/10.17226/19012.