About ME/CFS

Details

Last Updated: 06 January 2016 06 January 2016

What Is ME/CFS?

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is also known as the Chronic Fatigue Immune Dysfunction Syndrome (CFIDS). In February, 2015 the Institute of Medicine of the National Academy of Sciences released a report on the illness suggesting that the name be changed to Systemic Exertional Intolerance Disease (SEID). So far U.S. federal government agencies are still referring to the illness as ME/CFS or just Chronic Fatigue Syndrome (CFS), not SEID.

ME/CFS is a complex, serious, and debilitating illness which affects multiple systems of the body. People with ME/CFS experience profound exhaustion, post-exertional malaise, sleep disorder, autonomic dysfunction, neurological and flu-like symptoms, and cognitive problems such as difficulty thinking, processing, and remembering.

In 2014, in an updated version of a primer for clinicians (ME/CFS: A Primer for Clinical Practitioners —written by an international committee of physicians specializing in treating patients with the illness), the authors explain:

     "The key feature of the syndrome, post-exertional malaise, is a worsening of symptoms following minimal physical or mental activity which can persist for hours, days or even weeks and is not relieved by rest. The pathological loss of energy of ME/CFS is very different from the fatigue felt by healthy people following strenuous exercise or who are living under stress.

      "Chronic fatigue syndrome (CFS) is an inappropriate name for this serious illness. Fatigue is universal in healthy people who have undergone too much activity or who have had insufficient rest. Chronic fatigue is also a frequent symptom in numerous other illnesses. The name ignores other abnormalities found in the illness and trivializes the severity of the symptoms."

Duration and course of the illness

ME/CFS may last many months or years. Symptoms may vary in severity and may wax and wane. A 25-year follow-up of his patients by Dr. David Bell found that some of his patients recovered, but some of those who didn't became increasingly incapacitated. The 10+ Long-term CFS Study found that the predominant symptoms became more neurological in patients ill more than fifteen years. More recent studies have found similar results.

Research has shown that there is no "typical" course of the illness. Both of the studies above found this. However, a 2014 New York multi-site study of ME/CFS patients ill more than five years found that temporary remissions, sometimes lengthy, were common.

While there is no known cure, many of the symptoms can be treated. Some patients show improvement over time, while others may show little improvement or a worsening of symptoms. The best strategy is for a patient to accept the fact of the illness and to develop coping skills that will make the situation as tolerable as possible. It is also important not to entirely give up on life, while waiting for the illness to resolve. It might not. See the section Living with ME/CFS for coping suggestions and the section on Treatment.

Who gets ME/CFS?

ME/CFS affects men, women, and children of all ages, ethnic and socioeconomic groups.  A very carefully conducted government-funded study (Jason et al.; Archives of Internal Medicine, Oct 11, 1999) estimated that there are about 1 million cases of ME/CFS in the US, with a majority of them being women.

This study found a prevalence among adolescents and children to be about half that of adults. The study also found the prevalence in women (522 per 100,000) is vastly higher than that for HIV in women (125 per 100,000), lung cancer in women (63 per 100,000) and breast cancer in women (43 per 100,000).

The study suggested that a high percentage of cases remain undiagnosed as a result of some patients' lower economic and medically uninsured status.

A 2008 study by the Centers for Disease Control & Prevention (CDC) now estimates the prevalence to be almost two million cases in the US, with 80% of them undiagnosed. However that study used a revised version of the 1994 CDC case definition, and probably over-estimates the prevalence.

---

How is ME/CFS diagnosed?

ME/CFS often resembles other illnesses, including Lyme disease, multiple sclerosis, mononucleosis, primary depression, mitochondrial disease and lupus.

In medicine, a "syndrome" is a set of signs and symptoms that occur together in a medical condition. For instance, AIDS is Acquired Immunodeficiency Syndrome, and until infection by the HIV virus was discovered to be the cause, diagnosis of AIDS was made solely by a collection of signs and symptoms. (In medicine, a "sign" is something that can be objectively measured by a physician and a "symptom" is something subjective experienced by a patient, such as severity of pain.)

In the 1980s, a number of U.S. physicians noticed what seemed to be an emerging syndrome. The Centers for Disease Control and Prevention (CDC) were called in to investigate an outbreak in the Lake Tahoe, Nevada area. Later the CDC convened a committee to come up with a research definition of the syndrome using signs and symptoms. This is now known as the 1988 CDC definition and the illness was named the Chronic Fatigue Syndrome (CFS).

In 1994, the CDC came up with a new research case definition, which loosened the requirements for diagnosis with ME/CFS. This is known as the 1994 CDC definition. Both definitions were intended to be used by researchers, to make sure their research subjects all had the same illness.

Unfortunately, it has been shown that the 1994 requirements were loosened too much compared to the 1988 definition, and people with other illnesses (including depression) were being mistakenly diagnosed as having ME/CFS. This has created major problems for the ME/CFS research results of the last 20 years, since in studies some of the subjects didn't have ME/CFS, but were mixed in with those who did. (See " Critique of the 1994 CDC definition " and the discussion "Are the illnesses described by the 1988 and 1994 CDC definitions the same?") 

Later a Canadian, Dr. Carruthers, led an international team of clinicians to come up with a definition of ME/CFS to be used by physicians who regularly see patients. This was published in 2003 under the auspices of the Canadian Ministry of Health.

This 2003 Canadian definition is what the physician authors of the Primer suggest be used for diagnosing ME/CFS. Unfortunately, the definition is complex. We will give a summary below. For more detail, see the article 2003 Canadian definition and pp. 43-44 of the ME/CFS: A Primer for Clinical Practitioners. All quotations below are from the original medical paper.¹

 

2003 Canadian case definition of ME/CFS

The definition first requires that other illnesses which could explain a patient's symptoms be ruled out. 

To have ME/CFS, a patient must meet all four of these criteria:

• "the criteria for fatigue, post-exertional malaise and/or fatigue, sleep dysfunction, and pain" explained below
• "have two or more neurological/cognitive manifestations"
• "one or more symptoms from the categories of autonomic, neuroendocrine and immune manifestations"
• "the illness persists for at least six months usually having a distinct onset, although it may be gradual." A "preliminary diagnosis may be  possible earlier."

Thus, to be diagnosed the person must qualify under each and all of the following symptom categories:

• "Fatigue: The patient must have a significant degree of new onset, unexplained, persistent, or recurrent physical and mental fatigue that reduces activity level. Three months is appropriate for children."

• "Post-exertional malaise...There is an inappropriate loss of physical and mental stamina, rapid muscular and cognitive fatigability, post-exertional malaise...and/or pain and a tendency of other associated symptoms within the patient's cluster of symptoms to worsen. There is a pathologically slow recovery period—usually 24 hours or longer."

• Sleep dysfunction: There is non-restorative sleep or decline in sleep quantity or dysregulation of normal sleep rhythms.

• Pain. "There is a significant degree of myalgia." The word means muscle pain, and is often the type of deep muscle pain experienced during the flu. "Pain can be experienced in the muscles/joints, and is often widespread and migratory in nature." There are often headaches of a "new type, pattern or severity."

• "Neurological/Cognitive Manifestations"—To qualify in this category two or more of the listed symptoms must be present. Please see the specific list of symptoms in the actual document. They are grouped into:

  a) cognitive deficits including problems with memory, information processing, difficulties with thinking, and perceptual disturbances

  b) more classical neurological symptoms, including difficulty walking and muscle weakness; sensory hypersensitivity, including lower threshold for emotional overload.

• "Autonomic, Neuroendocrine and Immune Manifestations"—To qualify under this category the patient must have at least one symptom from two of the following three subcategories. Often a patient will have multiple symptoms:

  a) "Autonomic Manifestations: orthostatic intolerance, neurally-mediated hypotension; postural orthostatic tachycardia; light-headedness; extreme pallor; nausea and irritable bowel syndrome; urinary frequency and bladder dysfunction; difficulty breathing upon exertion; palpitations with or without cardiac arrhythmias."

  b) "Neuroendocrine Manifestations: loss of thermostatic stability—subnormal body temperature...sweating episodes, recurrent feelings of feverishness and cold extremities; intolerance of heat and cold, marked weight change—anorexia or abnormal appetite; loss of adaptability and worsening symptoms with stress."

  c) "Immune Manifestations: tender lymph nodes, recurrent sore throats, recurrent flu-like symptoms, general malaise, new sensitivities to food, medications and or chemicals."

           

Reference

1. Carruthers et al. "Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Clinical Working Definition, Diagnostic and Treatment Protocols," Journal of Chronic Fatigue Syndrome 11, No. 1 (2003): 18-126.

---

Other Important ME/CFS Symptoms

Onset of the illness is often sudden (a few days to a few weeks.) Common symptoms (where patients were diagnosed with the 1988 or 1994 CDC case definitions) with their incidences are on the following list compiled from information provided by famous ME/CFS clinicians.

Most Common Symptoms of ME/CFS

• Exhaustion, made worse by physical exercise (100%)
• Low-grade fever in early stages (60-95%)
• Recurrent flu-like illness (75%)
• Frequent pharyngitis (sore throats) (50-75%)
• Joint and muscle pain (65%)
• Severe muscle weakness (40-70%)
• Stiffness (50-60%)
• Post-exertional fatigue & flu-like symptoms (50-60%)
• Multiple sensitivities to medicines, foods, and chemicals (40-60%)
• Severe nasal & other allergies (often with worsening of previous mild allergies) (40-60%)
• Frequently recurring, difficult to treat respiratory infections (40-60%)
• Dyspnea (labored breathing or hunger for air) on exertion
• Painful lymph nodes (especially on neck and under arms) (30-40%)
  
  

Neurological Symptoms

• Sleep disorders & unrefreshing sleep (50-90%)
• Headaches (35-85%)
• Visual blurring (50-60%)
• Intolerance of bright lights
• Parasthesias (numbness or tingling feelings) (30-50%)
• Dizziness/ Lightheadedness (30-50%)
• Ringing in the ears
• Impaired cognition (50-85%)
  • Attentional difficulties
  • Calculation difficulties
  • Memory disturbance
  • Spatial disorientation
  • Saying the wrong word

    Other Symptoms

• Worsening of premenstrual symptoms (70% of women)
• Nocturia (excessive urination during the night) (50-60%)
• Tachycardia (abnormal rapid heart action) (40-50%)
• Chest pain (25-40%)
• Cough (30-40%)
• Weight gain (50-70%)
• Nausea, especially in earlier stages (50-60%)
• Diarrhea, intestinal gas or irritable bowel (50%)
• Intolerance of alcohol
• Night sweats (30-50%)
• Dry eyes (30-40%)
• Dry mouth (30-40%)
• Rash (30-40%)
• Frequent canker sores (30-40%)
• Herpes simplex or shingles (20%)
• Symptoms worsened by extremes in temperature

 

(Statistics compiled from data by: Paul Cheney MD, Anthony Komaroff MD, Charles Lapp MD, Daniel Peterson MD)

---

What Causes ME/CFS?

The cause of ME/CFS is not yet known, but current research shows strong evidence of immune, neuroendocrine, and circulatory system dysfunction. Research indicates that some parts of the immune system may be in an overactive state, while other parts of the system may be in an underactive state. There is convincing evidence that viruses or persistent viral fragments are associated with ME/CFS in many cases.

The authors of ME/CFS: A Primer for Clinical Practitioners (p. 43) have this to say about causality:

       "ME/CFS usually occurs as sporadic (isolated) cases, but clusters of cases have occurred worldwide. Some outbreaks have affected large
numbers of individuals in a particular community, hospital, or school. In sporadic cases, 20% of patients have another family member with the illness. These facts suggest that both genetic and environmental factors may contribute to the illness.

"ME/CFS frequently starts with acute, 'flu-like' symptoms and immune system changes found in ME/CFS are similar to immune system changes
found in some viral infections. A number of infectious agents have been found more frequently in patients with ME/CFS than in the general population,
but no infectious agent has been proven to be the cause.

"To avoid any possible contamination of the blood supply, patients with ME/CFS should refrain from donating blood.

"Occasionally, ME/CFS has been triggered by environmental toxins, the receipt of an immunizing injection, or surviving a
major trauma.

"Although depression and anxiety may occur secondary to the illness, research studies have shown that ME/CFS and major depressive disorder
can be distinguished by behavioral, immunological and hormonal testing.

"The Centers for Disease Control and Prevention (CDC) recognizes CFS as an organic syndrome, not a psychiatric disorder." 

---

How is ME/CFS treated?

Since there is no known cause or cure, treatment is targeted to relieve specific symptoms, such as pain and sleep disorder. Experienced ME/CFS clinicians are treating patients with both conventional and alternative approaches. Experimental treatments are being evaluated in clinical trials. Patients need to assess their treatment options carefully for safety and effectiveness. (See our detailed Treatment section.)

Because some patients can show lower tolerance or hypersensitivity to medications, treatment should be started at low doses with gradual increases as appropriate. Since anesthesia can also trigger hypersensitive reactions, caution must be exercised when an ME/CFS patient undergoes a procedure using anesthesia. (See the suggestions of Dr. Charles Lapp concerning the use of anesthesia.)

Important lifestyle changes include: increased rest, decreased and carefully paced activity ("living in your energy envelope"), exercise only as tolerated, stress control, balanced nutrition, improved sleep, and identifying effective coping strategies.

Patient and family support groups, as well as counseling, can be very helpful. It is vital to find a physician who understands ME/CFS, and is willing to develop an individualized treatment program.

---

What about kids?

Children develop ME/CFS, but they are often misdiagnosed. An accurate pediatric definition of ME/CFS has only been in existence since 2006.

Children tend to experience symptoms of short-term memory and concentration problems, dizziness, light-headedness, abdominal pain, rash, fever, and chills. They frequently experience profound fatigue as well, although they may have difficulty expressing their complaints or judging the severity of their condition.

Thus, some people may incorrectly perceive that the child is developing progressive learning and social difficulties rather than a physical illness. (Please see our Pediatric ME/CFS section for more information.)

---

More resources

Clinical Guides to Diagnosis and Treatment

Complementary & Mainstream Treatment Approaches

Conventional Medicine Treatment for ME/CFS

Critique of the 1994 CDC case definition

Dr. Anthony Komaroff, An Overview of Research on CFS, summary of lecture April 24, 2010

History of ME/CFS/CFIDS

Leading doctors explain ME/CFS in videos and text

ME/CFS: A Primer for Clinical Practitioners

ME/CFS Self-Care: The Basics

On the Morbid Fascination with Psychiatric Morbidity

The ME/CFS Initiation–A Primer for New Patients

The Physical Basis of CFS

Critique of the CDC Case Definitions

Details

Last Updated: 30 November 2015 30 November 2015

1994 Definition and Overlap with Psychiatric Conditions

The 1994 U.S. Centers of Disease Control & Prevention (CDC) case definition for the Chronic Fatigue Syndrome (CFS) is flawed because the committee which designed and authored it (under the auspices of the CDC) was constituted by 3 different groups with opposing viewpoints concerning the nature of the illness.

The first group was made up of clinicians who had become experienced with the illness as a result of its recent outbreaks in different parts of the country in both its epidemic and endemic forms. These physicians had seen hundreds of patients with very similar, coherent illnesses of flu-like and neurological symptoms that seemed to follow no usual diagnostic pattern. Initial research had been undertaken that demonstrated immune system abnormalities and the presence of higher than normal levels of antibodies to viruses, as well as the viruses themselves, in the blood and tissues of patients.

The second group on the committee, mainly from the CDC, wished to lump this illness with many other "fatiguing illnesses"—the main symptom for diagnosis would be the extreme fatigue. Such a diagnostic scheme would allow for CFS and primary depression and even cancer to be identified as CFS.

The third group was made up of psychiatrists and others who believed CFS was a psychiatric illness, likely somatoform disorder, neurasthenia, "atypical depression", or somatization disorder.

Hence the 1994 definition was a "compromise by committee". It can diagnose CFS correctly, but could also diagnose a psychiatric disorder as CFS, because of the loose requirement of having only 4 of 7 symptoms to qualify—once the fatigue requirement is met. An individual can be diagnosed as having CFS by having only the following four symptoms:

1. unrefreshing sleep;
2. headaches of a new type;
3. neuropsychological complaints, including problems with short-term memory and concentration;
4. muscle pain, or multi-joint pain without swelling or redness.

Sleep and memory problems, headaches, and muscle pain, in addition to being a few of the common CFS symptoms, are also symptoms of a variety of other illnesses, including psychiatric illnesses such as depression and anxiety disorder. A strict observance of the Criteria differentiates CFS from Generalized Anxiety Disorder (DSM-IV 300.021); Major Depressive Disorder (DSM IV); and Somatoform Disorders (DSM-IV). (N.B. DSM-IV is the Diagnostic and Statistical Manual of Mental Disorders, 4th edition.)

However, only a physician or psychiatrist thoroughly familiar with the necessary qualifying symptoms of each of the psychiatric disorders and of ME/CFS would be able to make the differential diagnoses. The fact that the four qualifying symptoms, above, for CFS can also represent important qualifying symptoms for psychiatric illness can lead to patients with psychiatric illness being erroneously diagnosed with CFS.

Moreover, the allowance of neurasthenia as a co-morbid illness in CFS diagnosis, as well as the fact that the DSM-IV requirements for neurasthenia provide for an overlap with five of the seven 1994 CFS criteria leads to utter confusion between the two illnesses—depending on whether the conditions' symptoms are interpreted "medically" or "psychiatrically."

Hence a doctor who interprets the patient's symptoms medically arrives at a diagnosis of CFS. But if the doctor interprets the symptoms psychiatrically, the diagnosis is neurasthenia.

It's obvious that many psychiatrists (who are familiar with the neurasthenia diagnosis) might be prone to interpreting CFS symptoms psychiatrically. In fact, the history of CFS has been one of confusion between the actual physical illness and various psychiatric illnesses. Some of this confusion was codified in the 1994 definition.

---

Need to improve the CDC Definitions

The 2003 Canadian definition is the most accurate definition so far—until one or more definitive diagnostic markers are found for ME/CFS. However, prior to the development of the Canadian definition, interest in improving the 1994 CDC definition was intense (for obvious reasons). Numbers of researchers are still working to improve the 1994 definition.

Because of the confusing and diagnostically porous nature of the 1994 Criteria, a number of the top international researchers most familiar with ME/CFS, decided to return to the earlier 1988 CDC CFS Criteria as a starting point for fashioning a suggested CFS symptom criteria with greater specificity in selecting CFS cases and in differentiating CFS from other fatiguing illness diagnoses.

There is no doubt that the 1988 (Holmes) CDC CFS Definition is more rigorous, selective and accurate in describing and defining the clusters of illness reported by various clinicians around the country than the 1994 CDC definition.

As it was more rigorous and selective, it was less open diagnostic confusion—the misdiagnosis of ME/CFS as another illness, and the diagnosis of other illnesses as ME/CFS. It should also be noted that, in many ways, the 1988 Criteria is a better guide to careful clinical investigation of the illness (except for the requirement that a diagnosis of CFS be excluded in the presence of anxiety disorder and some non-major mental illnesses).

---

Summary of the findings of a number of research efforts to improve the 1988 CDC Definition

What symptoms are the most discriminating in CFS?

In 1996, Komaroff et al. in a paper, "An Examination of the Working Case Definition of Chronic Fatigue Syndrome," published in the American Journal of Medicine (v. 100, Jan. 1996) conducted an exhaustive statistical analysis of the frequency of symptoms in CFS patients compared with the frequency of the same symptoms in samples of healthy control subjects, Multiple Sclerosis(MS) patients, and patients with major depression. The object was to determine which symptoms associated with CFS best discriminated CFS from the healthy controls and the patients in the two disease comparison groups.

Those symptoms which best discriminated CFS would be the basis for an improved case definition.

Of the symptom-criteria in the better 1988 definition "...the discriminating ability was clearest for myalgias, post-exertional malaise, headaches, and a group of infectious-type symptoms (i.e., fever/chills, sore throat, swollen neck glands, swollen arm glands). All these symptoms were found much more frequently...[in the CFS cases than] in either of the two comparison groups (p<0.01)"

However, patients with MS were just as likely to report the symptom of muscle weakness than those patients with CFS. In contrast, patients with major depression were less likely to report muscle weakness than those in the CFS and MS groups.

Interestingly, 84% of the CFS patients experienced sudden onset, while 0% of patients with major depression had a sudden onset.

Komaroff et al. also compared 31 other symptoms characteristic of CFS with their incidence in the control and disease comparison groups. These symptoms were in 5 categories: respiratory, gastrointestinal, neurologic, rheumatological, and miscellaneous.

Four of the 31 symptoms: poor appetite (anorexia), nausea, tingling sensations, and alcohol intolerance were reported significantly less often by patients in the disease comparison groups than by CFS patients.

As already discussed, the 1994 CDC Diagnostic Criteria is deficient in that it reduces, in comparison with the 1988 CDC definition, the number of qualifying physical symptoms—namely it omits fevers or chills, muscle weakness (often indicative of a neurological problem) and sudden onset. By doing so, the characteristic clinical picture of the illness is distorted and undermined.

Based on the Komaroff article, a careful clinician could confirm diagnosis of ME/CFS by the 2003 Canadian Criteria or by using the 1988 CDC definition criteria with the addition of poor appetite, nausea, tingling sensations and alcohol intolerance.

Komaroff et al also proposed eliminating the "Physical Criteria" from the 1988 definition, which require confirmation in the physician's office. As it may be difficult, due to fluctuation of symptoms, to obtain the required temperature during a doctor's visit, the patient can keep a record of his/her own temperature fluctuations. It is probably reasonable to maintain swollen lymph nodes and nonexudative pharyngitis for physician examination.

Are the illnesses described by the 1988 and 1994 CDC definitions the same?

In 1998, at the AACFS Conference, Natelson et al. presented a poster entitled "Do the 1988 and 1994 CFS case definitions identify the same illness?"

The results were as follows: "When subjects who met the 1988 case criteria (n=45) were compared to those who met only the 1994 criteria (n=17), subjects in the 1988 group were found to suffer from a more severe form of the illness. Specifically, subjects in the 1988 group demonstrated more severe symptoms as well as a greater reduction in activity. The latter group also more frequently reported infectious-type symptoms..."

The conclusions were: "The 1988 and 1994 CFS case definition criteria appear to identify distinct patient groups. Given that the subjects of the 1988 group more frequently endorsed infectious symptoms and more frequently reported a sudden flu-like illness onset, an infectious etiology for this group is hypothesized."

Finally, in September of 2001, De Becker, McGregor, and De Meirleir published "A definition-based analysis of symptoms in a large cohort of patients with chronic fatigue syndrome." The article was published in the Journal of Internal Medicine.

The article begins: "The Holmes [1988] and Fukuda [1994] criteria are widely used criteria all over the world...yet a specific European study regarding chronic fatigue syndrome (CFS) symtomatology has not been conducted...This study was performed to answer the need to assess the homogeneity of a large CFS population in relation to the Fukuda and Holmes definition...

"A total of 2073 consecutive patients with major complaints of prolonged fatigue participated in this study...Of the 2073 patients complaining of chronic fatigue (CF), 1578 CFS patients fulfilled the Fukuda criteria (100% of CFS group), and 951 (60.3% of the CFS group) fulfilled the Holmes criteria...The Holmes criteria was more strongly associated than the Fukuda definition with the symptoms that differentiated the CFS patients from the patients that did not comply with the CFS definitions. The inclusion of 10 additional symptoms were found to improve the sensitivity/specificity for the selection of CFS patients.

"Whilst the Fukuda and Holmes definition are very similar, the Fukuda definition is less stringent...and is likely to include a greater and more heterogeneous group of patients with profound fatigue...

"...[This] shows that the patients who were included under the CFS definition using the Fukuda criteria had less severe symptoms and an altered symptom prevalence distribution to those patients classified under the Holmes criteria.

"The different definition groups...were compared using standard discriminant function analysis with the Holmes profile with the addition of attention deficit, paralysis, new sensitivities to food/drugs, difficulties with words, urinary frequency, cold extremities, photophobia, muscle fasiculations, lightheadedness, exertional dyspnea, and gastrointestinal disturbance. The symptoms were chosen as they represented the 10 symptoms with the greatest prevalence differences between the Holmes and Fukuda criteria....

"Thus the addition of 10 extra symptoms to the Holmes criteria results in a small increase in definition sensitivity and a much larger increase in specificity and improves the accuracy of the definitions. [Emphasis added..]

"The study showed that the analysis of individual symptom severity and prevalence revealed that the Holmes criteria patients had increased symptom prevalence and severity of many of the symptoms that determine the difference between CFS patients and CF subjects compared with the Fukuda defined group...Thus, the addition of patients to the CFS definition by the Fukuda criteria has resulted in the selection of less severely affected patients. This has also resulted in the introduction of an increase in patient symptom heterogeneity." [I.e., less of a clearly defined illness entity].

---

Conclusions to draw

 What are patients and physicians too make of all these different diagnostic criteria and important research suggestions for their modification?

First, when acceptable to the physician, diagnose using the 2003 Canadian definition.

Second, in order to confirm the diagnosis, the patient and physician may want to make a careful comparison with the Holmes criteria (disregarding the exclusion of non-major mental illness diagnoses) using the additional symptoms suggested by Komaroff et al. and De Meirleir et al.

Third, when a patient is applying for public or private sector disability and insurance programs, such diagnosis should also be specifically documented using the 1994 CDC criteria.

---

More resources

AACFS Clinical Conference Report 2003

Cardiac Symptoms and Abnormalities Documented in CFS Patients: (A summary of 4 studies by Lerner et al.)

Komaroff, Progress on Chronic Fatigue Syndrome Research, 2008

On the Morbid Fascination with Psychiatric Morbidity

The Physical Basis of CFS

U.S. Centers for Disease Control publishes pilot study on gentically-based metabolic differences on exercise challenge between CFIDS patients and controls