According to the Institute of Medicine, Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) affects 836,000 to 2.5 million Americans. ME/CFS is a disease that is characterized by profound fatigue, cognitive dysfunctions, sleep abnormalities, autonomic manifestations, pain, and other symptoms, all of which are made worse by any exertion. The Institute of Medicine (IOM) created a report developed by an expert committee to help redefine the illness and proposed new diagnostic criteria that will help medical professionals understand the illness and accurately diagnose and manage patients with this often-misunderstood disease. The IOM committee also recommended that it be renamed Systemic Exertion Intolerance Disease (SEID) to reflect the main characteristics of the disease.
Background
The true prevalence of MF/CSF is unknown because an estimated 84%-91% of affected people have not been diagnosed, and its cause is unknown; however, symptoms may be triggered by certain infections such as Epstein-Barr Virus. MF/CFS is a disease that is more common in women than men, with an average age of onset at 33 years. At some point in the course of this illness, one quarter of affected patients have been bed- or house bound. As explained by the IOM report, most patients have symptoms for years and never regain their predisease functioning level. There is no cure; however, there are interventions and therapies that are helpful in managing symptoms.
Because of the patients’ loss of functioning, high medical costs accrue that add to the overall annual economic burden of $17 billion to $24 billion.
Diagnostic criteria
The following three symptoms must be present to make the diagnosis as stated in the IOM report:
At least one of the two following manifestations also is required:
Key considerations
Diagnosing ME/CFS can be challenging. The health professional should diagnose only after a full history, physical, medical work-up, referrals to appropriate specialists to help rule out other potential disorders, and, ultimately, fulfillment of the diagnostic criteria. The severity and frequency of a patient’s symptoms over the past month and beyond should be assessed by the health professional to determine if the symptoms meet the diagnostic criteria of being chronic, moderate to severe, and frequent. An important distinguishing feature of ME/CFS is that the patient needs to have been symptomatic for 6 months, because most other causes of fatigue do not last that long. Fibromyalgia and irritable bowel syndrome are common comorbidities found in patients with ME/CFS.
Core symptoms
Fatigue and impairment. ME/CFS causes a profound fatigue that does not improve a lot by rest and is not associated with excessive exertion. This type of fatigue makes a substantial impact in decreasing a patient’s functioning and impairing the ability to return to a pre-illness state within occupational, educational, social or personal activities. The impairment secondary to fatigue must persist for at least 6 months.
Postexertional malaise. This symptom is unique to ME/CFS and was described as the primary feature. Physical or cognitive stressors that were previously tolerated now produce worsening symptoms and functioning.
Unrefreshing sleep. There was no subjective evidence of sleep disorders due to ME/CFS, but sufficient data did show that unrefreshing sleep was a complaint universally among ME/CFS patients. The IOM recommends that while polysomnography is not a requirement to diagnose ME/CFS, it is encouraged, to rule out other primary sleep disorders.
Cognitive impairment. Increased stress, effort, or time pressure all can exacerbate existing problems that a patient with ME/CFS has with thinking or executive functioning. Evidence has shown that patients with ME/CFS have slowed information processing and this may be a central aspect of these patients’ overall neurocognitive impairment.
Orthostatic intolerance. Symptoms have been shown to worsen with an upright posture according to objective measures such as orthostatic vital signs and head-up tilt testing, and symptoms improve with rest and leg elevation.
Additional symptoms
Additional common manifestations that were found present in ME/CFS are pain, immune impairment, and infection. Pain was prevalent in more severe cases and manifested as headaches, arthralgia, and myalgia, among others. The pain that these patients experience was indistinguishable from pain experienced in other disease states and healthy people. Immune impairment was evident in people with ME/CFS, in that there were data demonstrating poor NK cell cytotoxicity function. The severity of the illness correlated to the degree of immune impairment. The function of this NK cell was proposed to potentially be a biomarker for the severity of ME/CSF, although not specific to the disease. Finally, there was evidence that ME/CFS can often follow an infection with Epstein Barr Virus (EBV).
The Bottom line
ME/CFS (SEID) is a serious disease that affects many Americans and impacts their lives in cognitive, emotional, physical, and economic realms. The IOM has described a clear diagnostic algorithm for patients presenting with profound fatigue. There are tools that can be found within the report that help to assess the quality, severity, and frequency of the core symptoms. Further research is needed to determine what causes this SEID, what factors affect its course, and what therapies work for which patients.
References
IOM (Institute of Medicine). Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness. Washington, DC: The National Academies Press; 2015. http://www.iom.edu/mecfs.
Dr. Skolnik is associate director of the family medicine residency program at Abington (Pa.) Memorial Hospital and professor of family and community medicine at Temple University in Philadelphia. Dr. Baranck Drumond is a chief resident in the family medicine residency program at Abington Memorial Hospital and is going into practice at a Federally Qualified Health Center, The Community Health Center of Cape Cod in Mashpee, Mass.
