The importance of estimating prevalence of ME/CFS in future epidemiological studies of long COVID, 2023, Grabowska et al

Andy

Andy

Retired committee member
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.

https://www.researchgate.net/public..._future_epidemiological_studies_of_long_COVID
 
It's great to have a paper saying this. It (assessing PEM in Long Covid cases) should have been obvious, but of course it wasn't.

The 1994 CDC criteria is mainly a research tool for ME/CFS diagnosis.
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The 2003 CCC is basically a diagnostic tool for clinical settings.
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The 2015 IOM criterion is also a primary diagnostic tool for clinical settings.
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I wonder if we should be encouraging the use of the Fukuda name for this criteria, rather than the CDC name? I think so. It feels as though the CDC label has become more prevalent lately - I might be imagining it, but it has certainly been favoured by BPS authors. Mentioning the CDC brings all the authority of that significant organisation.

These authors are well-informed and, I'm pretty sure, sympathetic to people with ME/CFS. I would have hoped that they would not have given the Fukuda criteria the status as the sole research criteria.

Recommends the use of DePaul Symptoms Questionnaire, and specifically DSQ-PEM:
We recommend that future epidemiological studies of LC use the DePaul Symptoms Questionnaire (DSQ) (31) or the UKMEB Symptoms Assessment Questionnaire (27), as diagnostic tools enabling the identification of cases meeting commonly used diagnostic criteria for ME/CFS. Given the cardinal importance of PEM in ME/CFS diagnosis, one should make the effort to accurately capture its different aspects, such as recovery time, frequency, and severity (32). In this scenario, one can use the DePaul Symptoms Questionnaire dedicated to PEM specifically, the so-called DSQ-PEM (33). The use of this questionnaire is likely to be more informative than simply asking for the presence of symptoms worse after even minor physical or mental effort, as done in large study of LC (26). The reporting of the epidemiological findings could be done via a recommended guideline for the minimal data elements on ME/CFS research (34). Besides typical information about study design and demographics, one should report the case definition used, the symptom inventory, the excluded medical and psychiatric conditions and co-morbidities, and self-reported functional impairment/levels of activity.
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Notes that the IOM criteria don't impose exclusionary conditions.
The major difficulty to comply with the 1994 CDC and the 2003 CCC in epidemiological studies lies in the exclusion of other medical conditions that could explain fatigue. The 2015 IOM criterion, alternatively, does not impose any exclusionary conditions (23), however, they still require a clinical assessment and consideration of differential diagnosis. This case definition is already being used to report the frequency of ME/CFS cases among LC cases (26,35). However, the use of the 2015 IOM criteria might lead to inconsistent findings across studies due to variations in frequency of co- morbidities present in different populations. It might also overestimate the prevalence of ME/CFS due to highly-frequent conditions, such as diabetes and obesity in suspected cases. For example, forty-three percent of participants fit the 2015 IOM criterion for ME/CFS in an LC study (35). Among these compliant individuals, some had a BMI ≥45 kg/m2.
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Fair points about the poor quality of LC epidemiological studies
We also recommend raising the standard of research and reporting in LC, ME/CFS, and other chronic diseases; we made a similar recommendation for genetic association studies in ME/CFS (36). Our recommendation is based on two systematic reviews of LC prevalence data. One systematic review suggested that forty-five percent of LC cases had ME/CFS (37). However, this review incorrectly assumed that the persistence of fatigue was equivalent to ME/CFS. The other systematic review suggested that only a few epidemiological studies collected representative samples from the LC population (6). Low population representativeness, convenience sampling, and different sources of bias might be present in the remaining published studies (6). Randomness and sample representativeness are the pillars of a sound statistical inference. If a study does not minimally ensure these foundational assumptions, the subsequent statistical inference might be tricky, or even impossible (38).
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