ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

61–80 of 533 studies

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

Phosphoproteomic analysis reveals differential associations between liver-spleen disharmony and qi-blood deficiency syndromes in chronic fatigue syndrome.

Zhang, Jiabao, Tian, Ying, Sun, Guanghan et al.·Journal of translational medicine·2026

Researchers compared blood protein markers in 30 people—10 with ME/CFS showing Traditional Chinese Medicine (TCM) 'Liver-Spleen Disharmony' patterns, 10 with 'Qi-Blood Deficiency' patterns, and 10 healthy controls—using advanced protein analysis. They observed different patterns of phosphorylated proteins (chemical modifications on proteins) between the two ME/CFS groups and healthy controls, suggesting that TCM pattern categories may have distinct molecular signatures. However, this is an early exploratory study with a small sample size, and these findings have not yet been replicated.

BiomarkersDiagnostics

E2 ModerateCohortPEM unclearObservational

Hemodynamic Phenotyping in ME/CFS and ANOCA: Complementary Insights from Coronary Function Testing and Invasive Cardiopulmonary Exercise Testing.

Mackay, Zoë, Shah, Samit, Villalobos, Jose Gomez et al.·American journal of physiology. Heart and circulatory physiology·2026

This observational study reports that among 261 patients diagnosed with a heart condition called ANOCA (angina with non-obstructive coronary arteries), approximately 18% also had ME/CFS. In a separate group of 27 ME/CFS patients, 24 (89%) were found to have ANOCA when tested. The study used two diagnostic approaches—coronary function testing and exercise testing—to characterize heart and muscle responses during exertion, observing that ME/CFS patients showed a pattern of reduced muscle oxygen uptake despite normal oxygen delivery. These are early findings from a single centre and require confirmation through larger, prospective studies.

Autonomic Nervous SystemDiagnosticsPost-Exertional Malaise

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

E2 ModerateCohortPEM unclearCase-Control

ICD-10 Diagnoses prior to ME/CFS diagnosis in children and young people suggest potential early diagnostic indicators.

Wirth, Marielle, Haastert, Burkhard, Linnenkamp, Ute et al.·Scientific reports·2026

This study looked at medical records of young people (ages 6-27) diagnosed with ME/CFS to see what health problems they had in the year before their diagnosis. Researchers found that certain conditions—like fatigue, depression, pain disorders, and post-COVID-19 condition—appeared more often in people who later developed ME/CFS compared to similar young people who didn't develop it. This suggests these earlier diagnoses might be early warning signs or related to ME/CFS development, though the study cannot prove they actually caused ME/CFS.

Diagnostics

E2 ModerateCohortPEM requiredCross-Sectional

Total blood volume and red blood cell volume are not associated with orthostatic intolerance in adults with myalgic encephalomyelitis/chronic fatigue syndrome.

Yamazaki, Tadahiro, Mancini, Donna M, Blate, Michelle et al.·Physiological reports·2026

Researchers measured blood volume in 49 adults with ME/CFS and tested how their bodies responded to standing (using a lean test). They found that about half had abnormal responses to position changes, but these abnormalities were not clearly linked to whether participants had low, normal, or high blood volume. The findings suggest that other body systems—like nerve function or blood vessel control—may be more important than blood volume alone in explaining why many ME/CFS patients feel dizzy or unwell when standing.

BiomarkersAutonomic Nervous SystemDiagnostics

E2 ModerateCohortPEM unclearCross-Sectional

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome diagnostic reporting in the 2021-2023 National Health Interview Survey.

Fleig, Katherine, Nahin, Richard, Stussman, Barbara et al.·BMC public health·2026

A survey of over 86,000 US adults found that approximately 1.5% reported ever receiving an ME/CFS diagnosis. Among those, about 21% reported they no longer have the condition (Past ME/CFS), though roughly 40–50% of this group still experience symptoms and functional limitations similar to those currently diagnosed. This study observed that people who report having recovered from ME/CFS remain more impaired than those who never had the diagnosis, suggesting that reported recovery does not necessarily mean full symptom resolution.

Diagnostics

E2 ModerateCohortPEM requiredObservational

Handgrip strength in children, adolescents, and young adults with suspected myalgic encephalomyelitis/chronic fatigue syndrome.

Mihatsch, Lorenz, Schartner, Lisa, de Luna, Julia Lange et al.·Journal of translational medicine·2026

Researchers tested whether handgrip strength could help identify ME/CFS in young people (ages 10–25). They asked 147 patients referred for ME/CFS assessment and 83 healthy controls to squeeze a hand-strength device twice, an hour apart. Young people with ME/CFS had weaker grip strength than healthy controls, and grip strength was loosely associated with physical functioning; however, grip strength alone could not reliably tell apart ME/CFS patients from other young people with chronic fatigue. The study shows that repeated handgrip testing is feasible and may help track how patients are doing over time, but early findings suggest it works better as a way to measure general weakness rather than as a standalone diagnostic test.

BiomarkersDiagnosticsPost-Exertional Malaise

E2 ModerateCohortPEM unclearCase-Control

Interpreting hand grip strength in hospital employees with post-COVID syndrome compared to non-infected controls: a case-control study.

Tack, Matthias, Gruber, Rosalie, Betting, Leia et al.·Scientific reports·2026

This small study compared hand grip strength in 19 hospital workers with post-COVID syndrome (including 7 who met ME/CFS criteria) to 23 healthy controls. Researchers found that grip strength tended to be lower in the post-COVID group, particularly when tested a second time after a 60-minute break, which might suggest difficulty recovering after repeated effort. However, these are preliminary findings from a small group, and the authors note that grip strength alone is not reliable enough to diagnose post-COVID syndrome.

DiagnosticsPost-Exertional Malaise

E2 ModerateCohortPEM unclearLongitudinal

Two-timepoint multidomain follow-up of post-COVID condition and ME/CFS: overlapping autonomic, small-fiber, and cognitive changes.

Azcue, N, Barranco, C, Tijero-Merino, B et al.·Journal of translational medicine·2026

Researchers compared 21 people with post-COVID condition and 17 people with ME/CFS over about 2.5 years, measuring nerve function, autonomic symptoms, and cognitive performance. They observed that both groups showed similar patterns of changes over time—including worsening processing speed and cold sensation sensitivity, but improving heat sensation thresholds and verbal memory. While the two conditions appeared increasingly alike on follow-up testing, the study does not establish whether they are truly the same disease or simply share overlapping symptoms.

Pain and SensitizationAutonomic Nervous SystemDiagnosticsCognitive Impairment

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 ModerateCohortPEM unclearCross-Sectional

3D Virtual Reality Performance Metrics as a Future Fatigue Biomarker in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS).

Ladek, Anja-Maria, Priebe, Leonie, Harrer, Thomas et al.·Biomedicines·2026

Researchers tested how quickly 60 ME/CFS patients and 60 healthy controls could react to visual tasks presented in 3D virtual reality. ME/CFS patients showed slower reaction times across all difficulty levels, and they improved less with practice than controls did. The study reports an association between ME/CFS and prolonged reaction times, though the findings are preliminary and whether this could become a reliable test for fatigue severity requires further validation.

BiomarkersDiagnosticsCognitive Impairment

E2 ModerateCohortPEM unclearObservational

Wearable Heart Rate Variability Monitoring, Autonomic Dysfunction and Post-exertional Malaise in Long COVID: An Observational Study.

Ruijgt, Twan M, Slaghekke, Anouk, Ellens, Anneke et al.·Sports medicine (Auckland, N.Z.)·2026

This observational study measured heart rate variability (a marker of nerve system balance) in 121 long COVID patients and 21 healthy controls using wearable devices over multiple days. Researchers observed that long COVID patients had lower heart rate variability during daily activities and sleep, and their heart rate variability remained reduced for 24 hours after exercise, particularly at intensities above their aerobic threshold. The findings suggest wearables may help patients recognise when they are overexerting, though the study does not yet establish whether this monitoring prevents post-exertional malaise.

BiomarkersAutonomic Nervous SystemDiagnosticsPost-Exertional Malaise

E2 ModerateCohortPEM unclearCase-Control

Circulating extracellular vesicles-microRNAs as potential biomarkers for the identification of ME/CFS: differentiating fatigue-related conditions.

Eguchi, Akiko, Kuratsune, Hirohiko, Nakatomi, Yasuhito et al.·Journal of translational medicine·2026

Researchers analysed tiny particles called extracellular vesicles in blood samples from patients with ME/CFS, chronic fatigue without a known cause, and depression, looking for differences in small RNA molecules that could help diagnose ME/CFS. They found a pattern of 114 different RNA molecules that appeared associated with ME/CFS and were rarely seen in healthy people, though these findings come from a small group of patients and have not yet been replicated in larger studies.

NeuroinflammationBiomarkersDiagnosticsLong COVID Overlap

E2 ModerateCohortPEM unclearObservational

Cardiopulmonary exercise test results do not change over two sequential days in patients with chronic fatigue syndrome.

Mancini, Donna M, Cook, Dane B, Brunjes, Danielle L et al.·Frontiers in physiology·2026

Researchers asked whether doing two exercise tests on consecutive days could reliably detect post-exertional malaise (PEM) in ME/CFS patients. They found that oxygen consumption and other key exercise measures did not change between Day 1 and Day 2 in either ME/CFS patients or healthy controls. However, ME/CFS patients reported much greater fatigue during exercise and had lower maximum heart rates. One study's findings do not establish whether this two-day test method is truly useful for measuring PEM in clinical practice.

DiagnosticsPost-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

Metabolomic Classification of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome via Explainable Ensemble Learning and Pareto-Guided Feature Selection.

Yagin, Fatma Hilal, Korkmaz, Yavuz, Colak, Cemil et al.·International journal of molecular sciences·2026

Researchers analysed blood metabolite patterns (small molecules in blood) from 106 people with ME/CFS and 91 healthy controls using machine learning to see whether these patterns could distinguish ME/CFS from health. A computer model called Explainable Boosting Machine achieved 91% accuracy in this one study group. Importantly, the findings remain preliminary—they describe associations observed in this cross-sectional sample and require external validation in new populations before clinical use.

BiomarkersEnergy MetabolismDiagnostics

E2 ModerateDiagnosticPEM unclearMethods-Paper

Agreement and reliability between the two-day 6-minute incremental step test and two-day cardiopulmonary exercise test in post COVID-19 condition for assessing post-exertional malaise: The REVEAL-study.

Bomans, Sarah, Michotte, Naomi, El M'Rabet, Imane et al.·PloS one·2026

Researchers compared two different exercise tests—one simpler and potentially more accessible (the 6-minute incremental step test) and one more complex (the cardiopulmonary exercise test)—to see if they could both measure post-exertional malaise in long COVID patients. In a small study of 25 people, the two tests did not measure the same outcomes equally well, though some measures like fatigue and effort perception showed moderate agreement. The simpler test may need further refinement before it can reliably replace the standard test.

DiagnosticsPost-Exertional Malaise

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Evidence Atlas

Evidence browser

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

Phosphoproteomic analysis reveals differential associations between liver-spleen disharmony and qi-blood deficiency syndromes in chronic fatigue syndrome.

Hemodynamic Phenotyping in ME/CFS and ANOCA: Complementary Insights from Coronary Function Testing and Invasive Cardiopulmonary Exercise Testing.

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.

ICD-10 Diagnoses prior to ME/CFS diagnosis in children and young people suggest potential early diagnostic indicators.

Total blood volume and red blood cell volume are not associated with orthostatic intolerance in adults with myalgic encephalomyelitis/chronic fatigue syndrome.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome diagnostic reporting in the 2021-2023 National Health Interview Survey.

Handgrip strength in children, adolescents, and young adults with suspected myalgic encephalomyelitis/chronic fatigue syndrome.

Interpreting hand grip strength in hospital employees with post-COVID syndrome compared to non-infected controls: a case-control study.

Two-timepoint multidomain follow-up of post-COVID condition and ME/CFS: overlapping autonomic, small-fiber, and cognitive changes.

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

3D Virtual Reality Performance Metrics as a Future Fatigue Biomarker in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS).

Wearable Heart Rate Variability Monitoring, Autonomic Dysfunction and Post-exertional Malaise in Long COVID: An Observational Study.

Circulating extracellular vesicles-microRNAs as potential biomarkers for the identification of ME/CFS: differentiating fatigue-related conditions.

Cardiopulmonary exercise test results do not change over two sequential days in patients with chronic fatigue syndrome.

Metabolomic Classification of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome via Explainable Ensemble Learning and Pareto-Guided Feature Selection.

Agreement and reliability between the two-day 6-minute incremental step test and two-day cardiopulmonary exercise test in post COVID-19 condition for assessing post-exertional malaise: The REVEAL-study.

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