The Prospects of the Two-Day Cardiopulmonary Exercise Test (CPET) in ME/CFS Patients: A Meta-Analysis, Eun-Jin Lim, 2020

[John Mac]

Abstract
Background:
The diagnosis of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is problematic due to the lack of established objective measurements.
Postexertional malaise (PEM) is a hallmark of ME/CFS, and the two-day cardiopulmonary exercise test (CPET) has been tested as a tool to assess functional impairment in ME/CFS patients.
This study aimed to estimate the potential of the CPET.

Methods:
We reviewed studies of the two-day CPET and meta-analyzed the differences between ME/CFS patients and controls regarding four parameters:
volume of oxygen consumption and level of workload at peak (VO2peak, Workloadpeak)
and at ventilatory threshold (VO2@VT, Workload@VT).

Results:
The overall mean values of all parameters were lower on the 2nd day of the CPET than the 1st in ME/CFS patients, while it increased in the controls.
From the meta-analysis, the difference between patients and controls was highly significant at Workload@VT (overall mean: −10.8 at Test 1 vs. −33.0 at Test 2, p < 0.05), which may reflect present the functional impairment associated with PEM.

Conclusions:
Our results show the potential of the two-day CPET to serve as an objective assessment of PEM in ME/CFS patients.
Further clinical trials are required to validate this tool compared to other fatigue-inducing disorders, including depression, using well-designed large-scale studies.

https://www.mdpi.com/2077-0383/9/12/4040/htm

 

[ME/CFS Skeptic]

Strange that they only included 5 studies. I thought they were quite a few more: Keller et al. 2014, Lien et al. 2019, Davenport 2020, and the ones by Van Campen/Visser.

@Snow Leopard

 

[Kitty]

It’s great that the work has been done, but surely 2-day CPET in its current form is never going to be useful as a diagnostic tool? Putting aside the ethical and practical issues, most ME patients aren’t going to get anywhere near VO2 max. I can barely get out of breath before my muscles start to give up.

It’s not necessary anyway. It’d be great to have a biomarker, of course, but properly trained primary care practitioners using a reliable case definition shouldn’t have much difficulty making a diagnosis even without one. The areas that really need attention are the ‘properly trained’ and ‘reliable’ parts!

 

[Grigor]

Good to see a meta-analysis like this but indeed strange they only included 5 studies.

Has this group published about ME before? Never heard of them.

 

[Snow Leopard]

Strange that they only included 5 studies. I thought they were quite a few more: Keller et al. 2014, Lien et al. 2019, Davenport 2020, and the ones by Van Campen/Visser.

@Snow Leopard

Van Campen/Visser and Keller 2014 were not case-control studies.

Not including Lien 2019 and Davenport 2020 is disappointing. The latter suggests the analysis was conducted before Davenport 2020 was published. The exclusion of Lien 2019 is likely due to Lien et al. not providing numerical values/SD for the parameters used in the meta-analysis.

Good to see a meta-analysis like this but indeed strange they only included 5 studies.

Has this group published about ME before? Never heard of them.

This group has been conducting systematic reviews - eg of case definitions, prevalence etc. I expect this is so that they can be translated into Korean guidelines.

https://www.researchgate.net/scientific-contributions/Eun-Jin-Lim-2170994814

 

[Mike Dean]

They were thorough and picked up over 200 studies, so they used strict inclusion criteria as a filter - see the flowchart in the text. I don't see a table of excluded studies (maybe online somewhere?), but I expect @Snow Leopard is right about Lien. They searched until June 2020, hence Davenport missing. This looks ok as a review & meta-analysis.