Charlotte Stephens, Research Correspondent, ME Association.
We show below brief summaries of the research studies about ME/CFS that have been published in the last week, followed by the abstracts from those studies.
This information has been included in the monthly update to the central Research Index which is freely available as a download.
The Index has now been updated to include all studies up to the end of May 2020.
This is an A-Z of the most important published research studies and selected key documents and articles, listed by subject matter, on myalgic encephalomyelitis and/or chronic fatigue syndrome (ME/CFS).
You can use it to easily locate and then read any research in a particular area that you might be interested in, e.g. epidemiology, infection, neurology, post-exertional malaise etc.
You can also find the Research Index in the Research section of the website together with a list of Research Summaries from the ME Association that provide lay explanations of the more important and interesting work that has been published to date.
ME/CFS Research Published 22nd – 28th May 2020
This week, 2 new research studies have been published:
1. The EUROMENE research group conducted a review of studies looking into the prevalence and incidence of ME/CFS in Europe. They found three studies in which the prevalence ranged from 0.1-2.2%, however, they concluded that studies on prevalence and incidence in Europe are scarce and highlighted the need for epidemiological studies to be carried out.
2. Researchers from Johns Hopkins University in America looked at whether the widely-used formula to estimate an individual’s anaerobic threshold (55% of predicted maximal heart rate for age), which is used for pacing using a heart rate monitor, was accurate in comparison to measurements taken from Cardiopulmonary exercise testing (CPET).
After testing this is on 90 ME/CFS patients, they concluded, “Formulae generated in an attempt to help those with ME/CFS exercise below the anaerobic threshold do not reliably predict actual heart rates at the lactic acidosis threshold as measured by a cardiopulmonary exercise test.”
ME/CFS Research references and abstracts
1. Estevez-Lopez F et al. (2020)
Systematic Review of the Epidemiological Burden of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Across Europe: Current Evidence and EUROMENE Research Recommendations for Epidemiology.
Journal of Clinical Medicine 9 (5).
This review aimed at determining the prevalence and incidence of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) in Europe.
We conducted a primary search in Scopus, PubMed and Web of Science for publications between 1994 and 15 June 2019 (PROSPERO: CRD42017078688).
Additionally, we performed a backward-(reference lists) and forward-(citations) search of the works included in this review. Grey literature was addressed by contacting all members of the European Network on ME/CFS (EUROMENE). Independent reviewers searched, screened and selected studies, extracted data and evaluated the methodological and reporting quality.
For prevalence, two studies in adults and one study in adolescents were included. Prevalence ranged from 0.1% to 2.2%. Two studies also included incidence estimates. In conclusion, studies on the prevalence and incidence of ME/CFS in Europe were scarce.
Our findings point to the pressing need for well-designed and statistically powered epidemiological studies. To overcome the shortcomings of the current state-of-the-art, EUROMENE recommends that future research is better conducted in the community, reviewing the clinical history of potential cases, obtaining additional objective information (when needed) and using adequate ME/CFS case definitions; namely, the Centers for Disease Control & Prevention−1994, Canadian Consensus Criteria, or Institute of Medicine criteria
2. Van Campen CL et al. (2020)
Heart Rate Thresholds to Limit Activity in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients (Pacing): Comparison of Heart Rate Formulae and Measurements of the Heart Rate at the Lactic Acidosis Threshold during Cardiopulmonary Exercise Testing.
Advances in Physical Education 10 (2).
Introduction: Based on the hypothesis that oxidative metabolism is impaired in ME/CFS, a previous study recommended a pacing self-management strategy to prevent post-exertional malaise.
This strategy involved a prescription to maintain a heart rate below the anaerobic threshold during physical activities. In the absence of lactate sampling or a cardiopulmonary exercise test (CPET), the pacing self-management formula defines 55% of the age-specific predicted maximal heart rate as the heart rate at the anaerobic threshold.
Thus far there has been no empiric evidence to test this self-pacing method of predicting heart rate at anaerobic threshold. The aim of this study was to compare published formula-derived heart rates at the anaerobic threshold with the actual heart rate at the lactic acidosis threshold as determined by CPET.
Methods and Results: Adults with ME/CFS who had undergone a symptom-limited CPET were eligible for this study (30 males, 60 females). We analysed males and females separately because of sex-based differences in peak oxygen consumption.
From a review paper, formulae to calculate maximal predicted heart rate were used for healthy subjects. We compared the actual heart rate at the lactic acid threshold during CPET to the predicted heart rates determined by formulae.
Using Bland-Altman plots, calculated bias: the mean difference between the actual CPET heart rate at the anaerobic threshold and the formula predicted heart rate across several formulae varied between -28 and 19 bpm in male ME/CFS patients.
Even in formulae with a clinically acceptable bias, the limits of agreement (mean bias ± 2SD) were unacceptably high for all formulae.
For female ME/CFS patients, bias varied between 6 and 23 bpm, but the limits of agreement were also unacceptably high for all formulae.
Conclusion: Formulae generated in an attempt to help those with ME/CFS exercise below the anaerobic threshold do not reliably predict actual heart rates at the lactic acidosis threshold as measured by a cardiopulmonary exercise test.
Formulae based on age-dependent predicted peak heart rate multiplied by 55% have a wide age-specific variability and therefore have a limited application in clinical practice.
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