Category: Case Definition

What Long COVID investigators can learn from four decades of ME/CFS research

Abstract:

Four decades of research in the field of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) have yielded lessons that may be instructive for those devising criteria to better comprehend Post-Acute Sequelae of SARS CoV-2 Infection (PASC) and Long COVID.

For instance, substantial effort has been devoted to defining classification systems, operationalizing methods, and developing instruments with adequate reliability and validity in the ME/CFS field.

The current article provides guidelines for developing a case definition for Long COVID and discusses the significance of psychometric issues and criterion variance, including how to specify symptoms, develop thresholds, subtypes, and exclusionary conditions. ME/CFS research could enhance our knowledge of Long COVID pathophysiology, early diagnosis, prognosis, and the identification of effective treatments.

Source: Leonard A. Jason, Benjamin H. Natelson, Hector Bonilla, Zaki A. Sherif, Suzanne D. Vernon, Monica Verduzco Gutierrez, Lisa O’Brien, Emily Taylor. What Long COVID investigators can learn from four decades of ME/CFS research. Brain Behavior and Immunity Integrative, Volume 4, 2023, 100022. https://www.sciencedirect.com/science/article/pii/S2949834123000211 (Full text)

The importance of estimating prevalence of ME/CFS in future epidemiological studies of long COVID

Abstract:

The resolution of the COVID-19 pandemic is giving rise to another public health challenge due to the explosion of long COVID (LC) cases. In many cases, LC results in persistent fatigue, post-exertional malaise (PEM), and other debilitating symptoms that resemble the clinical manifestation of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). The similarity of these two diseases suggests that future epidemiological studies of LC could take the opportunity to also estimate the prevalence of ME/CFS at a minimal cost.

With this opportunity in mind, we revisited the most consensual case definitions of ME/CFS for research purposes. We then compared the symptoms assessed at the participants’ enrollment in the UK ME/CFS Biobank with those documented in three systematic reviews encompassing hundreds of LC epidemiological studies. We found that published epidemiological studies of LC did not consistently assess or report the prevalence of PEM, which is a compulsory symptom for ME/CFS diagnosis. However, these studies assessed many neuro-cognitive, immunologic, and autonomic symptoms.

In this scenario, we recommend that the estimation of ME/CFS prevalence in the context of LC epidemiology is easily achievable by deploying tested and validated diagnosis tools used in ME/CFS. The knowledge of ME/CFS prevalence within the LC population is of cardinal importance to optimal allocation of resources and better design of healthcare interventions to manage and treat patients with this devastating disease.

Source: Anna D. Grabowska, Francisco Westermeier, Luís Nacul, Eliana Lacerda, Nuno Sepúlveda. The importance of estimating prevalence of ME/CFS in future epidemiological studies of long COVID. DOI:10.13140/RG.2.2.20997.52967 https://www.researchgate.net/publication/373043778_The_importance_of_estimating_prevalence_of_MECFS_in_future_epidemiological_studies_of_long_COVID (Full text)

Connectivity between Salience and Default Mode Networks and subcortical nodes distinguishes between two classes of ME/CFS

Abstract:

Myalgic Encephalomyelitis or Chronic Fatigue Syndrome (ME/CFS) is a debilitating disease with unknown pathophysiology. Functional MRI (fMRI) studies in ME/CFS have reported disparate connectivities for the brain salience (SA) and default mode (DMN) networks.

In this study, we acquired resting state and task fMRI with an advanced scanner for improved subject numbers: 24 healthy controls (HC) and 42 ME/CFS patients, 18 meeting International Consensus Criteria (ICC) and 24 meeting Fukuda criteria. We evaluated mean FC between SA and DMN network hub, and subcortical regions known to be involved in ME/CFS. We tested the hypothesis that ME/CFS connectivity differed from HC and the ICC and Fukuda classes are distinguished by different connectivities with HC for different pairs of SA, DMN or subcortical hubs.

During resting state fMRI only two connections differed from HC, both for Fukuda ME/CFS and both with an SA hub. During task fMRI 10 ME/CFS connections differed from HC, 5 for ICC and 5 for Fukuda. None were common to both classes. Eight of the 10 different connections involved an SA hub, six of 10 were weaker in ME/CFS, 4 stronger.

SA connections to the hippocampus and brainstem reticular activation system (RAS) differed from and were stronger than HC. The SA mediates the relative activity of the DMN and executive networks and imbalance will have functional consequences. The RAS and hippocampus modulate cortical activation. Different regulatory connections are consistent with the impaired cognitive performance and sleep-wake cycle of ME/CFS. Different neuropathology is involved in ICC and Fukuda classes.

Source: Su J, Thapaliya K, Eaton-Fitch N, Marshall-Gradisnik SM, Barnden LR. Connectivity between Salience and Default Mode Networks and subcortical nodes distinguishes between two classes of ME/CFS. Brain Connect. 2022 Nov 9. doi: 10.1089/brain.2022.0049. Epub ahead of print. PMID: 36352819. https://pubmed.ncbi.nlm.nih.gov/36352819/

The Hindi Version of International Consensus Criteria: A Cross-cultural Adaptation and Validation Study for Myalgic Encephalomyelitis in Post-COVID Patients

Abstract: 

Context: Fatigue is the most prominent feature of long COVID. With the increasing burden of long COVID cases post-acute phase of illness after recurrent waves of the pandemic, understanding its pathophysiology is of paramount importance.

Such fatigue and post-viral illness could be associated with features of neuroimmune exhaustion and thus be a part of a larger syndrome such as myalgic encephalomyelitis (ME).

Identifying the proportion of patients having ME from those experiencing fatigue would bring us one step closer to understanding the pathophysiology. International consensus criteria (ICC) originally published in English (ICC-E) is a valid and reliable tool for identifying cases of ME. However, a validated Hindi version of ICC-E is not available.

Aims: To develop and validate an equivalent version of ICC-E in the native Hindi language (ICC-H) to suit Indian patients and health care workers even at peripheries and to make conducting large scales surveys more feasible.

Subjects and methods: Once permission from the ethics board was granted, guidelines given by MAPI Research Trust were followed and ICC-H was developed from ICC-E, in the following steps: (a) translation to Hindi, (b) back translation, (c) comparison between the translated and back-translated version performed by experts, and (d) pre-pilot test in the intended population. The ICC-H was applied to 53 bilingual individuals knowing both Hindi and English.

Statistical analysis used: The distribution of Hindi and English questionnaires was analyzed using the Chi-square test and Spearman’s correlation coefficient was used for correlation between answers of each question.

Results: The score of individual items and its global score was highly correlated with each other (p<0.001). The scores of individual components and global scores of ICC-H at baseline and original ICC-E after 4 weeks did not differ significantly.

Conclusion: This study shows that the ICC-H is a valid and reliable instrument for the assessment of ME. ICC-H can be used for Hindi speaking population for identifying cases of ME.

Source: Shah M, Kakar A, Gogia A. The Hindi Version of International Consensus Criteria: A Cross-cultural Adaptation and Validation Study for Myalgic Encephalomyelitis in Post-COVID Patients. J Assoc Physicians India 2022;70(10):59–63. https://www.japi.org/x2d4b494/the-hindi-version-of-international-consensus-criteria-a-cross-cultural-adaptation-and-validation-study-for-myalgic-encephalomyelitis-in-post-covid-patients  https://www.researchgate.net/profile/Atul-Gogia/publication/364241915_Postgraduate_Student_2_Vice_Chairman_and_Senior_Consultant_The_Hindi_Version_of_International_Consensus_Criteria_A_Cross-cultural_Adaptation_and_Validation_Study_for_Myalgic_Encephalomyelitis_in_Post-/links/63405e8aff870c55ce0adebf/Postgraduate-Student-2-Vice-Chairman-and-Senior-Consultant-The-Hindi-Version-of-International-Consensus-Criteria-A-Cross-cultural-Adaptation-and-Validation-Study-for-Myalgic-Encephalomyelitis-in-Post.pdf (Full text available as PDF file)

Separating patients with SEID from those with CFS in the French ME/CFS Association, with some thoughts on nomenclature

Abstract:

In 2015, the American Institute of Medicine, now called the National Academy of Medicine, (IOM/NAM) proposed new diagnostic criteria for both Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and a new label: Systemic Exertion Intolerance Disease (SEID). This study aimed to evaluate the SEID criteria among members of the French Association of ME/CFS (ASFC) and their opinion about this new name. We sent an anonymous questionnaire to 494 ASFC members, using French-translated questions derived from the IOM/NAM tool kit. Among the 178/231 responding subjects who reported ME/CFS diagnosis, 150 (84%) met the criteria of SEID. For each set of questions, we identified some of them that significantly distinguished SEID from non-SEID patients concerning unrefreshing sleep, cognitive disorders, and orthostatic intolerance items.
Forty-six percent of the respondents considered the “SEID” terminology as more appropriate than “CFS”, 39% considered it inappropriate, and 15% had no opinion. Some questions better identified the SEID criteria. The IOM/NAM SEID criteria captured a large part of ASFC members suffering from ME/CFS. However, this new SEID label was not well accepted by the subjects, nor were the other denominations, suggesting that a better term should be found. Pending development of specific markers, further work with patient communities is needed to find a more suitable label.
Source: Campagne J, Fornasieri I, Andreani B, Eginard M, de Korwin J-D. Separating Patients with SEID from Those with CFS in the French ME/CFS Association, with Some Thoughts on Nomenclature. Diagnostics. 2022; 12(5):1095. https://doi.org/10.3390/diagnostics12051095. https://www.mdpi.com/2075-4418/12/5/1095 (Full text available as PDF file)

Evaluating case diagnostic criteria for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): toward an empirical case definition

Abstract:

Purpose: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is an illness characterized by a variety of symptoms including post-exertional malaise, unrefreshing sleep, and cognitive impairment. A variety of case definitions (e.g., the Canadian Consensus Criteria (CCC), the Myalgic Encephalomyelitis International Consensus Criteria (ME-ICC), and the Institute of Medicine (IOM) criteria) have been used to diagnose patients. However, these case definitions are consensus-based rather than empirical.

Materials and methods: The aim of the current study was to evaluate the validity of the aforementioned case definitions by factor analyzing a large, international sample (N = 2308) of ME/CFS symptom data. We performed primary and secondary exploratory factor analyses on the DePaul Symptom Questionnaire’s 54-item symptom inventory. These results were compared to the CCC, the ME-ICC, and the IOM criteria.

Results: We identified seven symptom domains, including post-exertional malaise, cognitive dysfunction, and sleep dysfunction. Contrary to many existing case criteria, our analyses did not identify pain as an independent factor.

Conclusions: Although our results implicate a factor solution that best supports the CCC, revisions to the criteria are recommended. Implications for rehabilitation: ME/CFS is a chronic illness with no consensus regarding case diagnostic criteria, which creates difficulty for patients seeking assistance and disability benefits. The current study compared three commonly used case definitions for ME/CFS by factor analyzing symptomological data from an international sample of patients. Our results suggest three primary and four secondary symptom domains which differed from all three case definitions. These findings could help reduce barriers to care for those disabled with ME/CFS by guiding the development of an empirically-based case definition.

Source: Conroy KE, Islam MF, Jason LA. Evaluating case diagnostic criteria for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): toward an empirical case definition. Disabil Rehabil. 2022 Mar 2:1-8. doi: 10.1080/09638288.2022.2043462. Epub ahead of print. PMID: 35236205. https://pubmed.ncbi.nlm.nih.gov/35236205/

Are there subgroups of chronic fatigue syndrome? An exploratory cluster analysis of biological markers

Abstract:

Background: Chronic fatigue syndrome (CFS) is defined according to subjective symptoms only, and several conflicting case definition exist. Previous research has discovered certain biological alterations. The aim of the present study was to explore possible subgroups based on biological markers within a widely defined cohort of adolescent CFS patients and investigate to what extent eventual subgroups are associated with other variables.

Methods: The Norwegian Study of Chronic Fatigue Syndrome in Adolescents: Pathophysiology and Intervention Trial (NorCAPITAL) has previously performed detailed investigation of immunological, autonomic, neuroendocrine, cognitive and sensory processing functions in an adolescent group of CFS patients recruited according to wide diagnostic criteria. In the present study, hierarchical cluster analyses (Ward’s method) were performed using representative variables from all these domains. Associations between clusters and constitutional factors (including candidate genetic markers), diagnostic criteria, subjective symptoms and prognosis were explored by standard statistical methods.

Results: A total of 116 patients (26.7% males, mean age 15.4 years) were included. The final cluster analyses revealed six clusters labelled pain tolerant & good cognitions, restored HPA dynamics, orthostatic intolerance, low-grade inflammation, pain intolerant & poor cognitions, and high vagal (parasympathetic) activity, respectively. There was substantial overlap between clusters. The pain intolerant & poor cognitions-cluster was associated with low functional abilities and quality of life, and adherence to the Canada 2003 diagnostic criteria for CFS. No other statistically significant cluster associations were discovered.

Conclusion: Within a widely defined cohort of adolescent CFS patients, clusters could be delineated, but no distinct subgroups could be identified. Associations between clusters and constitutional factors, subjective symptoms and prognosis were scarce. These results question the clinical usefulness of searching for CFS subgroups, as well as the validity of the most “narrow” CFS diagnostic criteria.

Source: Asprusten TT, Sletner L, Wyller VBB. Are there subgroups of chronic fatigue syndrome? An exploratory cluster analysis of biological markers. J Transl Med. 2021 Jan 30;19(1):48. doi: 10.1186/s12967-021-02713-9. PMID: 33516248; PMCID: PMC7847574. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7847574/ (Full text)

ME (Ramsay) and ME-International Case Criteria (ME-ICC): two distinct clinical entities

Excerpt:

The review of the differences and similarities in the different case definitions for myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS) by Lim and Son [1] deserves appreciation. Based on their analysis the authors acknowledge the “distinct view of ME and CFS” [2] and recognize four categories of case definitions: ME, ME/CFS, CFS [3] and Systemic Exertion Intolerance Disorder (SEID) [4].

Indeed these labels reflect very different case definitions [5]. According to Lim and Son [1] the first category comprises two ‘ME’ case definitions: ME (Ramsay) [6] and ME according to the International Case Criteria (ME-ICC) [7]. However as can be deduced from Table 2 [1], ME [6] and ME-ICC [7] are two distinct clinical entities [8].

Source: Twisk FNM. ME (Ramsay) and ME-International Case Criteria (ME-ICC): two distinct clinical entities. J Transl Med. 2020 Nov 25;18(1):447. doi: 10.1186/s12967-020-02617-0. PMID: 33239008. https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-020-02617-0 (Full text)

Review of case definitions for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)

Abstract:

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating disease with unknown causes. From the perspectives on the etiology and pathophysiology, ME/CFS has been labeled differently, which influenced changes in case definitions and terminologies. This review sought to feature aspects of the history, developments, and differential symptoms in the case definitions.

Methods: A search was conducted through PubMed published to February 2020 using the following search keywords: case definition AND chronic fatigue syndrome [MeSH Terms]. All reference lists of the included studies were checked. Of the included studies, the number of citations and the visibility in the literatures of the definitions were considered for comparisons of the criteria.

Results: Since the first ‘ME’ case definition was developed in 1986, 25 case definitions/diagnostic criteria were created based on three conceptual factors (etiology, pathophysiology, and exclusionary disorders). These factors can be categorized into four categories (ME, ME/CFS, CFS, and SEID) and broadly characterized according to primary disorder (ME-viral, CFS-unknown, ME/CFS-inflammatory, SEID-multisystemic), compulsory symptoms (ME and ME/CFS-neuroinflammatory, CFS and SEID-fatigue and/or malaise), and required conditions (ME-infective agent, ME/CFS, CFS, SEID-symptoms associated with fatigue, e.g., duration of illness). ME and ME/CFS widely cover all symptom categories, while CFS mainly covers neurologic and neurocognitive symptoms. Fatigue, cognitive impairment, PEM, sleep disorder, and orthostatic intolerance were the overlapping symptoms of the 4 categories, which were included as SEID criteria.

Conclusions: This study comprehensively described the journey of the development of case definitions and compared the symptom criteria. This review provides broader insights and explanations to understand the complexity of ME/CFS for clinicians and researchers.

Source: Lim EJ, Son CG. Review of case definitions for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). J Transl Med. 2020;18(1):289. Published 2020 Jul 29. doi:10.1186/s12967-020-02455-0 https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-020-02455-0 (Full text)

Solving the ME/CFS criteria and name conundrum: the aftermath of IOM

Abstract:

In 2015, the Institute of Medicine (IOM) proposed a new name and set of clinical criteria for what had previously been referred to as Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). This committee recommended the adoption of the term systemic exertion intolerance disease (SEID) and clinical criteria that required specific symptoms such as post-exertional malaise and unrefreshing sleep.

This article reviews efforts to evaluate the revised criteria as well as reactions to the new criteria and name. Since these recommendations have been made, the proposed name change has not been widely adopted by the scientific or patient community. Even though the IOM’s proposed criteria were intended to be a clinical rather than a research case definition, over the past few years, an increasing number of studies have employed these criteria for research purposes. One unwitting consequence of the IOM criteria, which excludes few other illnesses, is the broadening of the number of individuals who are diagnosed and included in research studies.

There is still a need to implement the IOM’s recommendation to form a multidisciplinary committee to review research and policy changes following the release of the new criteria. We conclude by presenting a possible roadmap for overcoming barriers in order to make progress on developing a consensus for a name and criteria.

Source: Leonard A. Jason & Madeline Johnson (2020) Solving the ME/CFS criteria and name conundrum: the aftermath of IOM, Fatigue: Biomedicine, Health & Behavior, DOI: 10.1080/21641846.2020.1757809 https://www.tandfonline.com/doi/abs/10.1080/21641846.2020.1757809?journalCode=rftg20