ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

41–60 of 510 studies

E0 ConsensusReviewPEM not requiredReview-Narrative

Chronic fatigue syndrome: the need for subtypes.

Jason, Leonard A, Corradi, Karina, Torres-Harding, Susan et al.·Neuropsychology review·2005

ME/CFS is a complex condition that affects people in different ways, and researchers found that treating it as one single disease may not be helpful. This review shows that patients with ME/CFS have different combinations of symptoms, different levels of disability, and different biological markers (measurable signs in the body), suggesting the condition should be divided into subtypes. Just like how different patients with diabetes or heart disease need different treatment approaches, ME/CFS patients might benefit from being grouped into categories so doctors can provide more targeted care.

Diagnostics

E0 ConsensusGuidelinePEM unclearGuideline

Chronic fatigue syndrome: a step towards agreement.

Clark, Christopher, Buchwald, Dedra, MacIntyre, Anne et al.·Lancet (London, England)·2002

This 2002 guideline paper from leading ME/CFS researchers brought together different international perspectives on how to define and diagnose chronic fatigue syndrome, aiming to reduce confusion among doctors. The authors reviewed existing diagnostic criteria and clinical approaches to help create more consistent standards for identifying the condition. This work was an important step toward getting doctors and researchers to agree on what ME/CFS actually is.

Diagnostics

E0 ConsensusGuidelinePEM unclearGuideline

Chronic fatigue syndrome. Clinical practice guidelines--2002.

Working Group of the Royal Australasian College of Physicians·The Medical journal of Australia·2002

These guidelines were created by Australian medical experts in 2002 to help doctors recognize, diagnose, and treat ME/CFS (a condition also called chronic fatigue syndrome). The guidelines set standards for how patients should be evaluated and managed, based on the best medical knowledge available at that time. They aim to improve the quality of care patients receive and reduce confusion about how to properly approach this illness.

Diagnostics

E0 ConsensusReviewPEM not requiredSystematic-Review

A review of the evidence for overlap among unexplained clinical conditions.

Aaron, L A, Buchwald, D·Annals of internal medicine·2001

This review examined eight unexplained illnesses—including ME/CFS, fibromyalgia, and irritable bowel syndrome—and found they share many similarities in symptoms (like fatigue and pain), how they affect daily life, and how they respond to laboratory tests. The researchers discovered that many patients have more than one of these conditions at the same time, suggesting they may be related or overlap in important ways.

Diagnostics

E0 ConsensusReviewPEM unclearSystematic-Review

Defining and managing chronic fatigue syndrome.

Mulrow, C D, Ramirez, G, Cornell, J E et al.·Evidence report/technology assessment (Summary)·2001

This 2001 review examined the medical literature on chronic fatigue syndrome to summarize what was known about how to define and manage the condition. The authors looked at existing research to identify consistent diagnostic criteria and treatment approaches. The goal was to create a clear picture of CFS based on the best available evidence at that time.

Diagnostics

E0 ConsensusReviewPEM not requiredReview-Narrative

Chronic fatigue syndrome and fibromyalgia: clinical assessment and treatment.

Friedberg, F, Jason, L A·Journal of clinical psychology·2001

This review examines how ME/CFS and fibromyalgia are similar conditions that doctors don't fully understand yet. The authors looked at research on what causes these illnesses, how to diagnose them (including checking for depression and anxiety), and what treatments work—including medications, alternative therapies, and talking with a therapist. The study suggests that mental health professionals can play an important role in helping patients manage their symptoms.

Diagnostics

E0 ConsensusReviewPEM not requiredReview-Narrative

Review of juvenile primary fibromyalgia and chronic fatigue syndrome.

Breau, L M, McGrath, P J, Ju, L H·Journal of developmental and behavioral pediatrics : JDBP·1999

This review examined research on fibromyalgia and chronic fatigue syndrome (ME/CFS) in children. The authors found that these conditions in young people may work differently than they do in adults, and that they might be more closely related to each other than previously thought. The review suggests that these illnesses are likely caused by biological and genetic factors rather than psychological problems.

Diagnostics

E0 ConsensusReviewPEM not requiredReview-Narrative

Functional somatic syndromes: one or many?

Wessely, S, Nimnuan, C, Sharpe, M·Lancet (London, England)·1999

This study looked at several long-term illnesses that cause many physical symptoms but don't show obvious damage on standard medical tests, including ME/CFS and irritable bowel syndrome. The researchers found that these conditions have much more in common with each other than previously thought—they affect similar types of patients, cause overlapping symptoms, and respond to treatment in similar ways. Rather than treating each condition as completely separate, the authors suggest doctors and researchers should think of them as related conditions on a spectrum.

Diagnostics

E0 ConsensusReviewPEM unclearReview-Narrative

Chronic fatigue syndrome in children and adolescents: a review.

Jordan, K M, Landis, D A, Downey, M C et al.·The Journal of adolescent health : official publication of the Society for Adolescent Medicine·1998

This review examined what was known about ME/CFS (chronic fatigue syndrome) specifically in children and teenagers. The authors looked at existing research to understand how the illness affects young people, how doctors recognize it, and what happens to patients over time. This study helps explain what ME/CFS looks like in younger patients, which is often different from how it appears in adults.

Diagnostics

E0 ConsensusReviewPEM not requiredEditorial

Chronic fatigue and chronic fatigue syndrome: shifting boundaries and attributions.

Lloyd, A R·The American journal of medicine·1998

This review examines how fatigue is defined and diagnosed, and how different definitions lead to very different estimates of how many people have chronic fatigue syndrome. The authors look at how doctors and researchers measure fatigue using patient reports, and explore whether fatigue that follows infections is a real medical condition. The study highlights that without clear, consistent definitions, it's difficult to understand the true scope of the problem.

Diagnostics

E0 ConsensusReviewPEM not requiredReview-Narrative

Epidemiologic advances in chronic fatigue syndrome.

Levine, P H·Journal of psychiatric research·1997

This review summarized what researchers knew about ME/CFS in 1997, including how common it is, who gets it, and what affects recovery. The study found that about 200 out of every 100,000 people have ME/CFS, and that women are more likely to develop it than men. The review also noted that people with sudden-onset ME/CFS tend to recover better than those whose symptoms start gradually.

Diagnostics

E0 ConsensusReviewPEM not requiredReview-Narrative

Fibromyalgia and chronic fatigue syndrome: similarities and differences.

Buchwald, D·Rheumatic diseases clinics of North America·1996

This review compared ME/CFS and fibromyalgia (FM), two conditions that cause fatigue, muscle pain, and sleep problems. The researchers found that these two illnesses are very similar in their symptoms and how they affect people's lives, even though doctors use different criteria to diagnose them. Some patients have both conditions at the same time, which makes their suffering worse.

SleepDiagnostics

E0 ConsensusReviewPEM unclearReview-Narrative

The epidemiology of chronic fatigue syndrome.

Wessely, S·Epidemiologic reviews·1995

This review examined what we know about how common ME/CFS is, who develops it, and how it varies across different populations and regions. The researchers looked at existing research to understand the overall patterns of this illness in society. This helps doctors and patients understand whether ME/CFS is rare or relatively common, and whether certain groups are more likely to be affected.

Diagnostics

E0 ConsensusReviewPEM not requiredEditorial

Fibromyalgia, chronic fatigue, and myofascial pain syndromes.

Goldenberg, D L·Current opinion in rheumatology·1992

This review examined research published on fibromyalgia and chronic fatigue syndrome, looking at what treatments work best and how these conditions are diagnosed. Researchers found that while many studies have been done, no single treatment has proven highly effective for either condition, and the way doctors diagnose chronic fatigue syndrome needs to be improved and made more consistent.

Diagnostics

E0 ConsensusGuidelinePEM unclearGuideline

A report--chronic fatigue syndrome: guidelines for research.

Sharpe, M C, Archard, L C, Banatvala, J E et al.·Journal of the Royal Society of Medicine·1991

This 1991 document provides guidelines for how researchers should study ME/CFS to ensure consistent and reliable findings. Rather than reporting new experimental results, it offers recommendations on how to standardize research methods, study design, and patient definitions. It represents the thinking of leading medical experts who were trying to establish a common framework for ME/CFS research.

Diagnostics

E0 ConsensusReviewPEM unclearEditorial

Postviral fatigue syndrome: time for a new approach.

David, A S, Wessely, S, Pelosi, A J·British medical journal (Clinical research ed.)·1988

This 1988 review examined how ME/CFS was being studied and discussed in medical literature, finding significant problems with how research was being conducted. The authors argued that the condition should not be viewed as simply 'all in your head' or 'purely physical,' but rather as involving multiple factors affecting the body and mind. They called for better research methods and clearer definitions before doctors could effectively help patients.

Diagnostics

E1 ReplicatedCohortPEM requiredObservational

Cardiopulmonary exercise testing and post-exertional malaise in ME/CFS: A retrospective analysis

Staci R. Stevens, Christopher R. Snell, Jared N. Stevens et al.·Journal of Translational Medicine·2018·n=51

ME/CFS patients underwent two consecutive days of cardiopulmonary exercise testing (CPET). On the second day, patients showed significantly reduced VO2 max and anaerobic threshold compared to the first day — and compared to healthy and disease controls who recovered normally. This objective impairment matches the subjective PEM experience.

DiagnosticsPost-Exertional Malaise

E2 ModerateCohortPEM unclearCase-Control

Sleep in myalgic encephalomyelitis/chronic fatigue syndrome shows marked night-to-night fluctuation under free-living conditions-results from a matched case-control study.

Saurel, Maïtena, Fornasieri, Isabelle, Del Sordo, Giovanna C et al.·Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine·2026

This study observed that people with ME/CFS who wore sleep-tracking wristbands for a week showed poorer sleep quality and more night-to-night variability in how well they slept compared to matched controls—even though they spent more time in bed. The sleep pattern was unstable from night to night, which may be an important feature of ME/CFS sleep problems that laboratory studies (typically 1–2 nights) do not capture.

SleepDiagnostics

E2 ModerateBehavioralPEM not requiredCross-Sectional

Who receives a diagnostic label for fibromyalgia, chronic fatigue syndrome, and irritable bowel syndrome? A study in the lifelines cohort.

Tattan, Mais, Hanssen, Denise J C, Rosmalen, Judith G M·Journal of psychosomatic research·2026

This study looked at over 150,000 people to understand why some people with ME/CFS, fibromyalgia, or irritable bowel syndrome receive a diagnosis while others with the same symptoms do not. The researchers found that only a small number of people who meet the criteria for these conditions actually get diagnosed—about 14% for ME/CFS. Several factors like sex, education level, other health conditions, and how often people visit doctors affected whether they received a diagnosis.

Diagnostics

E2 ModeratePEM unclearRegistry-Resource

Risk factors for severe post-COVID condition in children, adolescents, and young adults.

Donath, Quirin, Haegele, Matthias, Schindler, Daniela et al.·European journal of pediatrics·2026

This observational study from a German pediatric hospital followed 120 children and young adults with post-COVID condition (PCC), observing that those with more severe illness were more likely to have had 12 or more symptoms during their initial COVID-19 infection, alongside other acute symptoms such as trouble concentrating and fainting-like episodes. One quarter of participants met criteria for ME/CFS, and all of these were in the severely affected group; by analogy, if similar patterns apply to ME/CFS patients, early identification of high-symptom-burden acute illness might help predict who develops severe long-term illness. These findings are preliminary and come from a single hospital site.

Severe MEAutonomic Nervous SystemDiagnosticsCognitive Impairment

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Evidence Atlas

Evidence browser

Chronic fatigue syndrome: the need for subtypes.

Chronic fatigue syndrome: a step towards agreement.

Chronic fatigue syndrome. Clinical practice guidelines--2002.

A review of the evidence for overlap among unexplained clinical conditions.

Defining and managing chronic fatigue syndrome.

Chronic fatigue syndrome and fibromyalgia: clinical assessment and treatment.

Review of juvenile primary fibromyalgia and chronic fatigue syndrome.

Functional somatic syndromes: one or many?

Chronic fatigue syndrome in children and adolescents: a review.

Chronic fatigue and chronic fatigue syndrome: shifting boundaries and attributions.

Epidemiologic advances in chronic fatigue syndrome.

Fibromyalgia and chronic fatigue syndrome: similarities and differences.

The epidemiology of chronic fatigue syndrome.

Fibromyalgia, chronic fatigue, and myofascial pain syndromes.

A report--chronic fatigue syndrome: guidelines for research.

Postviral fatigue syndrome: time for a new approach.

Cardiopulmonary exercise testing and post-exertional malaise in ME/CFS: A retrospective analysis

Sleep in myalgic encephalomyelitis/chronic fatigue syndrome shows marked night-to-night fluctuation under free-living conditions-results from a matched case-control study.

Who receives a diagnostic label for fibromyalgia, chronic fatigue syndrome, and irritable bowel syndrome? A study in the lifelines cohort.

Risk factors for severe post-COVID condition in children, adolescents, and young adults.

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