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ME/CFS Atlas — A public knowledge atlas for ME/CFS

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ME/CFS Atlas is an evidence reference platform, not a medical provider. Content is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.

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ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

Evidence browser

Search and filter 6,145 studies by evidence level, diagnostic criteria, PEM status, and research domain. Each entry links to the original source.

Studies sorted by evidence level, then year. Browse by topic instead →

Evidence level (E0–E3) reflects study type and replication, not methodological quality. A weak systematic review still sits at E0. How evidence levels work →

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510 studies

E0 — Consensus637E1 — Replicated320E2 — Moderate2,768E3 — Preliminary2,420

ME/CFS4,014Long COVID212Post-infectious189Overlapping1,045

Required for diagnosis412Not specified / unclear2,201Not required3,532

Post-Exertional Malaise1,055Cognitive Dysfunction1,723Pain1,612Unrefreshing Sleep793Orthostatic Intolerance474

Cytokines816Gene Expression567Metabolomics469Neuroimaging466Autoantibodies457

Infection-Triggered1,170Long COVID Overlap580Pediatric492Severe228

Strong Phenotyping435Sex-Stratified326Severe ME Included116

Systematic Review263Meta-Analysis60RCT300

Peer-reviewed6,088Preprint3Unclear54

201–220 of 510 studies

E2 ModerateCohortPEM not requiredCross-Sectional

Variability in diagnostic criteria for chronic fatigue syndrome may result in substantial differences in patterns of symptoms and disability.

Jason, Leonard A, Helgerson, Jena, Torres-Harding, Susan R et al.·Evaluation & the health professions·2003

This study compared two different sets of diagnostic criteria used to identify ME/CFS: one created by Fukuda and colleagues, and another specifically for myalgic encephalomyelitis (ME). The researchers found that these two definitions identified somewhat different groups of patients, with important differences in neurological symptoms, psychiatric issues, fatigue, and joint/muscle pain. This matters because it means studies using different definitions may not be easily compared.

E2 ModerateCohortPEM not requiredCross-Sectional

Distinguishing patients with chronic fatigue from those with chronic fatigue syndrome: a diagnostic study in UK primary care.

Darbishire, L, Ridsdale, L, Seed, P T·The British journal of general practice : the journal of the Royal College of General Practitioners·2003

This study looked at 141 people in UK doctor's offices who came in with fatigue lasting six months or longer. The researchers found that about two-thirds had chronic fatigue that didn't quite meet the official ME/CFS definition, while one-third had ME/CFS. People with ME/CFS had more severe symptoms, were more likely to be depressed and unemployed, and visited their doctor much more often than those with chronic fatigue alone.

E2 ModerateCohortPEM unclearCross-Sectional

The head-up tilt test with haemodynamic instability score in diagnosing chronic fatigue syndrome.

Naschitz, J E, Rosner, I, Rozenbaum, M et al.·QJM : monthly journal of the Association of Physicians·2003

Researchers developed a simple test using a tilting table to measure how well the body controls blood pressure and heart rate in ME/CFS patients. By tilting people upright and measuring these vital signs, they found a pattern (called a haemodynamic instability score) that appeared in ME/CFS patients but not in healthy people or those with other conditions. This test could help doctors confirm an ME/CFS diagnosis with objective measurements rather than relying only on symptoms.

Autonomic Nervous SystemDiagnostics

E2 ModerateCohortPEM not requiredCross-Sectional

Comparing symptoms of chronic fatigue syndrome in a community-based versus tertiary care sample.

Jason, Leonard A, Plioplys, Audrius V, Torres-Harding, Susan et al.·Journal of health psychology·2003

This study compared ME/CFS symptoms between two groups of patients: those who sought care at major medical centers and those found in the general community. Researchers found that people being treated at tertiary care hospitals reported experiencing more symptoms than community members with ME/CFS. This suggests that the people typically studied in research may not represent all people living with ME/CFS.

E2 ModerateBehavioralPEM not requiredCross-Sectional

Unexplained fatigue syndromes in a multinational primary care sample: specificity of definition and prevalence and distinctiveness from depression and generalized anxiety.

Skapinakis, Petros, Lewis, Glyn, Mavreas, Venetsanos·The American journal of psychiatry·2003

This study looked at how different definitions of unexplained fatigue affect how many people are diagnosed and whether they also have depression or anxiety. Researchers interviewed over 5,400 primary care patients from 14 countries and found that when they required more physical symptoms in addition to fatigue, fewer people were diagnosed, but those diagnosed were more likely to also have depression or anxiety.

E2 ModerateCohortPEM not requiredObservational

Non-vascular claudication: a clinical conundrum.

Fasih, T, Pickin, M, Cuschieri, R J·International journal of clinical practice·2003

Doctors sometimes see patients complaining of leg pain that resembles poor circulation (claudication), but the pain isn't actually caused by blood vessel problems. This study looked at over 1,000 patients with suspected circulation problems and found that 33 had other causes for their symptoms, including spine problems, nerve damage, or other conditions. One patient was diagnosed with chronic fatigue syndrome (ME/CFS). The study highlights that doctors need to correctly identify the real cause of symptoms before recommending treatments.

E2 ModerateCohortPEM unclearCross-Sectional

Diagnosing chronic fatigue syndrome: comparison of a protocol and computerised questionnaires.

Prins, J B, Elving, L D, Koning, H et al.·The Netherlands journal of medicine·2003

This study looked at whether doctors and researchers using a computer questionnaire agreed on who has ME/CFS. They reviewed 516 patients with chronic fatigue and found that doctors and researchers agreed about 84% of the time. When they disagreed, it was usually because they couldn't agree on how severe the fatigue was or how much it affected daily life. Only 3% of patients had a physical medical condition that explained their fatigue.

E2 ModerateCohortPEM not requiredCross-Sectional

The prevalence of chronic fatigue syndrome in Iceland - a national comparison by gender drawing on four different criteria.

Líndal, Eiríkur, Stefánsson, Jón G, Bergmann, Sverrir·Nordic journal of psychiatry·2002

This study asked over 2,500 Icelanders about symptoms of chronic fatigue syndrome (CFS) to find out how many people have it. Different diagnosis criteria gave very different results—ranging from 0% to 4.9%—showing that how doctors define CFS matters a lot. The study found that women made up most of the people with CFS, and there were some interesting differences between men and women in their symptoms.

E2 ModerateCohortPEM not requiredCross-Sectional

Self-reported symptoms and medical conditions among 11,868 Gulf War-era veterans: the Seabee Health Study.

Gray, Gregory C, Reed, Robert J, Kaiser, Kevin S et al.·American journal of epidemiology·2002

This study surveyed nearly 12,000 Navy Seabees who served around the time of the 1991 Gulf War to understand their health problems. Compared to Seabees who didn't deploy to the Gulf, those who did reported significantly more health issues, including chronic fatigue syndrome, PTSD, chemical sensitivity, and irritable bowel syndrome. Women, reserve members, and certain military units had higher rates of these combined symptoms.

E2 ModerateCohortPEM not requiredCross-Sectional

Dry eyes and mouth syndrome--a subgroup of patients presenting with sicca symptoms.

Price, E J, Venables, P J W·Rheumatology (Oxford, England)·2002

This study looked at 34 patients who had dry eyes and dry mouth symptoms but did not meet the standard criteria for Sjögren's syndrome. These patients had many symptoms on questionnaires but few objective physical findings, and most of them also had features more typical of fibromyalgia or chronic fatigue syndrome rather than Sjögren's.

E2 ModerateCohortPEM not requiredCase-Control

Chronic fatigue in a population-based study of Gulf War veterans.

McCauley, Linda A, Joos, Sandra K, Barkhuizen, Andre et al.·Archives of environmental health·2002

Researchers studied Gulf War veterans to see how many had chronic fatigue that couldn't be explained by standard medical tests. They found that about 2.2% of veterans met the official criteria for ME/CFS, and another 5.1% had unexplained fatigue. Women veterans were more likely to have these conditions than men. Unlike some other ME/CFS patients, most of these veterans developed their fatigue gradually rather than suddenly.

E2 ModerateCohortPEM unclearCross-Sectional

Latent class analysis of symptoms associated with chronic fatigue syndrome and fibromyalgia.

Sullivan, P F, Smith, W, Buchwald, D·Psychological medicine·2002

Researchers studied 646 patients with ME/CFS and/or fibromyalgia to see if these are truly separate conditions or if they overlap significantly. Using statistical analysis of 32 common symptoms, they found that patients fell into four groups that differed in severity rather than type—suggesting these conditions are more similar to each other than previously thought. This challenges the traditional belief that ME/CFS and fibromyalgia are distinct disorders.

E2 ModerateCohortPEM not requiredCase-Control

Symptom occurrence in persons with chronic fatigue syndrome.

Jason, L A, Torres-Harding, S R, Carrico, A W et al.·Biological psychology·2002

This study compared symptoms between people with ME/CFS, people with depression, and healthy controls to understand which symptoms are specific to ME/CFS. The researchers found that certain pain symptoms (headaches, sore throat, joint and muscle pain) were common in ME/CFS but also appeared in depression. However, ME/CFS patients uniquely experienced widespread muscle weakness and various heart, lung, and nervous system symptoms that weren't seen in the other groups.

E2 ModerateBehavioralPEM unclearCross-Sectional

What is chronic fatigue syndrome? Heterogeneity within an international multicentre study.

Wilson, A, Hickie, I, Hadzi-Pavlovic, D et al.·The Australian and New Zealand journal of psychiatry·2001

This study looked at 744 people with chronic fatigue across eight countries to see if they formed different groups based on their symptoms. Researchers found two distinct subgroups: a larger group (68%) with less severe illness and fewer psychiatric issues, and a smaller group (32%) whose symptoms looked more like somatoform illness (where psychological factors strongly influence physical symptoms). Importantly, the proportion of people in each group varied dramatically between countries (6-48%), suggesting that how doctors diagnose and classify ME/CFS is not standardized worldwide.

DiagnosticsCognitive Impairment

E2 ModerateCohortPEM not requiredCross-Sectional

Patients' perceptions of medical care in chronic fatigue syndrome.

Deale, A, Wessely, S·Social science & medicine (1982)·2001

This study asked 68 ME/CFS patients about their experiences with medical care. Two-thirds of patients were unhappy with the care they received. Patients felt most satisfied when doctors listened, showed genuine interest, and communicated clearly—not necessarily when doctors could cure the illness. Patients were most frustrated when doctors were dismissive, confused about ME/CFS, or gave conflicting advice.

E2 ModerateCohortPEM not requiredCross-Sectional

A definition-based analysis of symptoms in a large cohort of patients with chronic fatigue syndrome.

De Becker, P, McGregor, N, De Meirleir, K·Journal of internal medicine·2001

This study looked at 2,073 patients with chronic fatigue to understand how well two common diagnostic criteria (Fukuda and Holmes) identify ME/CFS. The researchers found that the Holmes criteria selected patients with more severe symptoms, while the Fukuda criteria included a broader group with milder cases. Adding or removing certain symptoms from the current diagnostic criteria could help doctors better identify who truly has ME/CFS.

E2 ModerateCohortPEM not requiredCross-Sectional

Clinicopathological findings consistent with primary Sjögren's syndrome in a subset of patients diagnosed with chronic fatigue syndrome: preliminary observations.

Sirois, D A, Natelson, B·The Journal of rheumatology·2001

Some people with ME/CFS experience dry eyes and dry mouth, which are also common symptoms of Sjögren's syndrome, an autoimmune disorder. This study tested 25 ME/CFS patients and 18 healthy volunteers for signs of Sjögren's syndrome using eye tests, saliva gland biopsies, and blood tests. The researchers found that about one-third of the ME/CFS patients had findings consistent with primary Sjögren's syndrome, while none of the healthy volunteers did.

E2 ModerateCohortPEM not requiredCross-Sectional

Diagnosis of psychiatric disorder in clinical evaluation of chronic fatigue syndrome.

Deale, A, Wessely, S·Journal of the Royal Society of Medicine·2000

This study looked at how often ME/CFS patients are incorrectly diagnosed with psychiatric conditions like depression. Researchers found that about two-thirds of patients who had been labeled with a psychiatric diagnosis actually didn't have one, while about one-third of patients without a psychiatric diagnosis did have a treatable mental health condition. The study shows that distinguishing between ME/CFS and psychiatric disorders can be difficult, and doctors need better tools and training to get the diagnosis right.

E2 ModerateCohortPEM not requiredCross-Sectional

General practitioners' beliefs, attitudes and reported actions towards chronic fatigue syndrome.

Steven, I D, McGrath, B, Qureshi, F et al.·Australian family physician·2000

This study surveyed Australian doctors about what they think and do regarding ME/CFS. Most doctors who diagnose ME/CFS agreed on six key symptoms, including long-lasting fatigue that doesn't improve with rest and exhaustion after minor activity. However, nearly one-third of doctors didn't believe ME/CFS was a real condition and thought depression was the actual cause instead.

E2 ModerateDiagnosticPEM not requiredMethods-Paper

Screening for prolonged fatigue syndromes: validation of the SOFA scale.

Hadzi-Pavlovic, D, Hickie, I B, Wilson, A J et al.·Social psychiatry and psychiatric epidemiology·2000

This study developed and tested two screening tools (called SOFA/CFS and SOFA/GP) to help doctors identify patients with chronic fatigue syndrome and prolonged fatigue conditions. Researchers tested these tools with 770 CFS patients in specialist clinics and 1,593 people in regular primary care settings, and found that both instruments could reliably spot these fatigue syndromes. The study also showed that fatigue syndromes have distinct patterns that are separate from anxiety and depression, and these patterns remained stable over a 12-month follow-up.

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PEM Immune Neuro Metabolic Biomarkers Severe ME Long COVID Cognitive

Curated Collections

Thematic groupings by clinical question or research area.

Neuroinflammation Evidence

PET imaging and other studies providing evidence for brain inflammation in ME/CFS.

Metabolism & Mitochondria

Metabolomics and mitochondrial function studies revealing energy metabolism disruption.

Biomarkers

Studies identifying potential biological markers for ME/CFS diagnosis and stratification.

PEM-Specific Research

Studies specifically examining post-exertional malaise, the hallmark symptom of ME/CFS.