The 2015 definition by the National Academy of Medicine (then referred to as the "Institute of Medicine") is not a definition of exclusion (differential diagnosis is still required). "Diagnosis requires that the patient have the following three symptoms: 1) A substantial reduction or impairment in the ability to engage in pre-illness levels of occupational, educational, social, or personal activities, that persists for more than 6 months and is accompanied by fatigue, which is often profound, is of new or definite onset (not lifelong), is not the result of ongoing excessive exertion, and is not substantially alleviated by rest, and 2) post-exertional malaise* 3) Unrefreshing sleep*; At least one of the two following manifestations is also required: 1) Cognitive impairment* 2) Orthostatic intolerance" and notes that "*Frequency and severity of symptoms should be assessed. The diagnosis of ME/CFS should be questioned if patients do not have these symptoms at least half the time with moderate, substantial, or severe intensity. "Clinical practice guidelines are generally based on case descriptions, with the aim of improving diagnosis, management and treatment. An example is the ME/CFS guideline for the National Health Services in England and Wales, updated in 2021. Other guidance can be found at the New York Department of Health. Differential diagnosis
Certain medical conditions can cause chronic fatigue and must be ruled out before a diagnosis of CFS can be given.
After evaluation of a persons history, risk factors, physical examination, laboratory testing and imaging, management begins depending on suspected diagnoses. Depending upon the diagnosis, a person may be placed in the intensive care unit, admitted to the hospital, or be treated outpatient. For persons with suspected cardiac chest pain or acute coronary syndrome, or other emergent diagnoses such as pneumothorax, pulmonary embolism, or aortic dissection, admission to the hospital is most often recommended for further treatment. Outpatient care
For people with non-cardiac chest pain, cognitive behavioral therapy might be helpful on an outpatient basis. A 2015 Cochrane review found that cognitive behavioral therapy might reduce the frequency of chest pain episodes the first three months after treatment. For persons with chest pain due to gastroesophageal reflux disease, a proton-pump inhibitor has been shown to be the most effective treatment. However, treatment with proton pump inhibitors has been shown to be no better than placebo in persons with noncardiac chest pain not caused by gastroesophageal reflux disease. For musculoskeletal causes of chest pain, manipulation therapy or chiropractic therapy, acupuncture,  or a recommendation for increased exercise are often used as treatment. Studies have shown conflicting results on the efficacy of these treatments. A combination therapy of nonsteroidal anti-inflammatory drugs and manipulation therapy with at-home exercises has been shown to be most effective in treatment of musculoskeletal chest pain. Epidemiology
Chest pain is a common presenting problem.