Skip to content

Start Here
Atlas
Evidence
Research
Ask
Updates
About
Support

Evidence Atlas

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

Start Here
Atlas
Evidence
Research
Ask
FAQ
Glossary
Updates
Methodology
Press
Retractions
Contribute
About
Support
Contact

Weekly research digest — no spam

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.

Generator v1·Scanner v1.4·Lint gate: enforce·See methodology

© 2026 ME/CFS Atlas

ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

Evidence browser

Search and filter 6,166 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 →

Sort

516 studies

E0 — Consensus643E1 — Replicated320E2 — Moderate2,781E3 — Preliminary2,422

ME/CFS4,025Long COVID216Post-infectious189Overlapping1,050

Required for diagnosis414Not specified / unclear2,218Not required3,534

Post-Exertional Malaise1,063Cognitive Dysfunction1,735Pain1,620Unrefreshing Sleep799Orthostatic Intolerance478

Cytokines818Gene Expression567Metabolomics473Neuroimaging468Autoantibodies458

Infection-Triggered1,174Long COVID Overlap587Pediatric493Severe231

Strong Phenotyping438Sex-Stratified326Severe ME Included118

Systematic Review265Meta-Analysis60RCT300

Peer-reviewed6,109Preprint3Unclear54

201–220 of 516 studies

E2 ModerateCohortPEM not requiredCross-Sectional

Factors influencing the diagnosis of chronic fatigue syndrome.

Solomon, Laura, Reeves, William C·Archives of internal medicine·2004

Researchers in Wichita, Kansas identified people with ME/CFS symptoms from the general population and found that only 16% had ever been diagnosed with the condition by a doctor. People were more likely to have received a diagnosis if they had moderate income, developed fatigue suddenly, or had tender lymph nodes and sore throat. This suggests that most people with ME/CFS in the community are never formally diagnosed.

E2 ModerateCohortPEM not requiredObservational

Chronic fatigue syndrome and other fatiguing illnesses in adolescents: a population-based study.

Jones, James F, Nisenbaum, Rosane, Solomon, Laura et al.·The Journal of adolescent health : official publication of the Society for Adolescent Medicine·2004

Researchers surveyed families in Kansas to see how many adolescents (ages 12-17) had chronic fatigue syndrome (CFS) or other long-term fatigue illnesses. They found that CFS is much less common in teenagers than in adults. When both teens and their parents were carefully evaluated by doctors, none of the participating teenagers actually met the full definition of CFS, though some had prolonged fatigue from other causes.

E2 ModerateCohortPEM not requiredCross-Sectional

The specificity of the CDC-1994 criteria for chronic fatigue syndrome: comparison of health status in three groups of patients who fulfill the criteria.

Kennedy, Gwen, Abbot, Neil C, Spence, Vance et al.·Annals of epidemiology·2004

This study looked at whether the standard definition of ME/CFS is specific enough to identify a single disease. Researchers compared three groups of patients who all met the official diagnostic criteria but got sick in different ways: some had gradual onset, some developed symptoms after Gulf War service, and some after pesticide exposure. They found important differences between these groups in their physical symptoms and emotional health, suggesting the current definition may be catching different conditions.

E2 ModerateCohortPEM unclearObservational

Incidence of fatigue symptoms and diagnoses presenting in UK primary care from 1990 to 2001.

Gallagher, Arlene M, Thomas, Janice M, Hamilton, William T et al.·Journal of the Royal Society of Medicine·2004

This study looked at how often fatigue and related diagnoses were recorded in UK doctor's offices between 1990 and 2001. While the overall number of fatigue diagnoses decreased, the number of people diagnosed with ME/CFS and fibromyalgia actually increased during this time. Interestingly, the number of people reporting fatigue symptoms stayed roughly the same, suggesting that doctors may have simply changed how they labeled and diagnosed these conditions rather than there being a real change in how many people were affected.

E2 ModerateCohortPEM unclearCross-Sectional

General practitioners' perceptions of chronic fatigue syndrome and beliefs about its management, compared with irritable bowel syndrome: qualitative study.

Raine, Rosalind, Carter, Simon, Sensky, Tom et al.·BMJ (Clinical research ed.)·2004

This study asked 46 general practitioners (GPs) in England about their views on ME/CFS and compared these with their views on irritable bowel syndrome. The researchers found that many GPs held negative stereotypes about ME/CFS patients, viewing them unfavorably because the condition has no clear physical marker, changes how it's classified over time, and conflicts with traditional ideas about work and illness. These negative attitudes made it harder for GPs to provide effective care.

E2 ModerateCohortPEM not requiredCross-Sectional

Differences between patients with chronic fatigue syndrome and with chronic fatigue at an infectious disease clinic in Stockholm, Sweden.

Evengård, Birgitta, Jonzon, Eva, Sandberg, Anneli et al.·Psychiatry and clinical neurosciences·2003

This study compared two groups of people with severe, long-lasting fatigue seen at an infectious disease clinic in Sweden: those who met criteria for ME/CFS and those with chronic fatigue (CF) but not ME/CFS. The main finding was that ME/CFS patients reported more physical symptoms and work disability, and most had a sudden onset following an infection, whereas CF patients had more mental health symptoms and a more gradual, burnout-like pattern. The researchers suggest these may be two different conditions with different underlying causes.

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 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 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 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

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 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 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 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 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 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 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 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.

← Previous Next 20 studies →

Or browse by topic

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.