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IOM 2015 Diagnostic Criteria

In 2015, the Institute of Medicine (IOM), now the National Academy of Medicine (NAM), published a report on ME/CFS called “Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness.” The IOM committee summarized the evidence base and proposed redefining the diagnostic criteria to facilitate timely diagnosis and to improve understanding of the illness among healthcare professionals and the public. Based on the report, IOM also published a report guide for healthcare providers [PDF- 4.77MB] that includes:

The 2015 IOM diagnostic criteria for ME/CFS in adults and children state that three symptoms and at least one of two additional manifestations are required for diagnosis. The three required symptoms are:

  1. A substantial reduction or impairment in the ability to engage in pre-illness levels of activity (occupational, educational, social or personal life) that:
    1. lasts for more than 6 months
    2. is accompanied by fatigue that is:
      1. often profound
      2. of new onset (not life-long)
      3. not the result of ongoing or unusual excessive exertion
      4. not substantially alleviated by rest
  2. Post-exertional malaise (PEM)* – worsening of symptoms after physical, mental or emotional exertion that would not have caused a problem before the illness. PEM often puts the patient in relapse that may last days, weeks, or even longer.
  3. Unrefreshing sleep* – patients with ME/CFS may not feel better or less tired even after a full night of sleep despite the absence of specific objective sleep alterations.

At least one of the following two additional manifestations must be present:

  1. Cognitive impairment* – patients have problems with thinking, memory, executive function, and information processing, as well as attention deficit and impaired psychomotor functions. All can be exacerbated by exertion, effort, prolonged upright posture, stress, or time pressure, and may have serious consequences on a patient’s ability to maintain a job or attend school full time.
  2. Orthostatic intolerance – patients develop a worsening of symptoms upon assuming and maintaining upright posture as measured by objective heart rate and blood pressure abnormalities during standing, bedside orthostatic vital signs, or head-up tilt testing. Orthostatic symptoms including lightheadedness, fainting, increased fatigue, cognitive worsening, headaches, or nausea are worsened with quiet upright posture (either standing or sitting) during day-to-day life, and are improved (though not necessarily fully resolved) with lying down. Orthostatic intolerance is often the most bothersome manifestation of ME/CFS among adolescents.

*The frequency and severity of these symptoms need to be evaluated. The IOM committee specified that “The 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.”

Other Common Symptoms of ME/CFS

Many people with ME/CFS also have other symptoms. Additional common symptoms include:

  • Muscle pain
  • Pain in the joints without swelling or redness
  • Headaches of a new type, pattern, or severity
  • Swollen or tender lymph nodes in the neck or armpit
  • A sore throat that is frequent or recurring
  • Chills and night sweats
  • Visual disturbances
  • Sensitivity to light and sound
  • Nausea
  • Allergies or sensitivities to foods, odors, chemicals, or medications

Disclaimer: The content of this ME/CFS website is for informational purposes only and does not represent a federal guideline or recommendation for the treatment of ME/CFS. The information provided on this website is not intended to be a substitute for the medical judgment of the healthcare provider and does not indicate an exclusive course of action or treatment.

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