A Quick and Practical Approach to Secure a Chronic Fatigue Syndrome Diagnosis: The Novel Functional Limitation Index 2023, Corbalan et al

[Sly Saint]

Abstract:
Chronic Fatigue Syndrome (CFS) is a serious, clinical, long-term condition with an unclear etiology and a difficult diagnosis. Our aim is to propose an objective physiological parameter (Functional Limitation Index, FLI) that describes the degree of functional impairment to support clinical suspicion.

Materials and Methods:
We consecutively included all CFS patients who consulted in the Exercise Physiology Department at our hospital, a dedicated referral unit for CFS, from 2009 to 2022. For comparison purposes, we included two control groups. Thus, three cohorts were included: the CFS group (patients with a previous definitive diagnosis), healthy voluntaries and a sportspeople/trained cohort (amateur athletes). All patients underwent a body composition test, spirometry, basal ECG in supine and standing positions and double peak effort ergospirometry with criteria of maximality.

Results:
The CFS+ group comprised 183 patients (85% female, mean age 46.2 years) and the CFS− included 161 cases (25.5% female, mean age 41.2 years); there were 93 patients in the healthy and 68 in the trained cohort. The CFS+ presented a lower functional class and scored worse in all of the performance parameters. The FLI was significantly higher in CFS+ (2.7 vs. 1.2; p < 0.001). The FLI displayed a good discrimination power (AUC = 0.94, p < 0.001), with a higher AUC than all of the other spirometric variables recorded. The best dichotomic overall FLI cutoff would be 1.66 with good specificity and sensitivity (S = 0.874, E = 0.864, Youden Index = 0.738).

Conclusions:
The Functional Limitation Index (FLI) could provide an easy and accurate diagnosis of this condition in both genders in a one-day assessment.

https://www.mdpi.com/2077-0383/12/22/7157

eta:

CFS group: Patients already diagnosed with a definitive CFS by other clinical specialists,
following the Fukuda diagnostic criteria [5] (Appendix A). These patients had
limited symptoms, including those mentioned above and were referred to our clinic
for that reason. Many of them required a study to assess disabilities. Patients with
doubtful or incomplete CFS diagnoses were not included.

 

[Andy]

What a joke. Until they use the same tests in other energy limiting conditions they have no idea whether what they propose allows for accurate diagnosis or not.

Also, the cohorts were mismatched, 85% female compared to 25.5% female, so there is the possibility, that they don't discuss, is that they have found a difference between male and female participants.

 

[Hoopoe]

The difficulty is distinguishing ME/CFS from other similar conditions, not from healthy volunteers or amateur athletes. Am I missing something?

 

[Trish]

Report from a hospital in Spain.
Given that the patients had already been diagnosed elsewhere, why were they sent to the "Exercise Physiology Department at our hospital, a dedicated referral unit for CFS"? Presumably for treatment of some sort, GET perhaps. If so, I wonder whether they did the same set of tests on them after treatment.

 

[Hutan]

The abstract doesn't read well but the paper seems to be generally sympathetic and relatively informed, at least as far as I have got. I mean they use Fukuda, which isn't great, but they are also talking about possible mitochondrial dysfunction. I think there are some translation issues e.g. 'limited symptoms' might be 'limiting symptoms'.

For the study of the patients, a protocol was used on a stationary bicycle specially adapted for patients with CFS that had the following stages:

• Three minutes no-load pedaling warm-up.
• Maximum test with progressive load of 15 w/m until the end of the test (maximum O2 consumption, VO2 max).
• Rest of three minutes with rest on the bicycle or minimal pedaling, at the patient’s decision.
• Supramaximal test started at the power equivalent to 50% of the maximum power reached in the test with a progression of 15 w every 10 s, until the exhaustion of the patient (supramaximal O2 consumption, VO2 smax).
• Rest period, without pedaling, until the patient recovered completely.

We developed an objective performance single value, the Functional Limitation Index (FLI), calculated as (VO2peak/VO2 SM)/(VO2 SM/VO2 predicted).

So, there's a sort of a repeat measure and there is calibration against predicted performance level, so it does take into account sex and age.

 

[Arnie Pye]

For someone with ME/CFS what are the benefits of actually having a diagnosis? Doesn't it actually make getting diagnosed for other non-ME conditions that much harder, since everything gets blamed on the ME?

 

[Hutan]

I guess if you want to recruit people for ME/CFS studies, or you want to participate in them, then its important to have a good way of diagnosing the illness. And research is really the only way out of this for us.

For an individual who doesn't want to participate in research, I agree, on balance a diagnosis probably doesn't help a lot. It might possibly help with access to benefits. It might help fight for accommodations e.g. by referencing the NICE Guideline. I think it is up to us and our patient organisations to try to make a diagnosis of ME/CFS something that is helpful rather than something that signals to doctors 'This person is a bit mad and difficult. Give them a wide berth if possible and don't give them tests and other assistance unless they have a medical problem as obvious as a broken leg.'

 

[ME/CFS Skeptic]

They write:

We developed an objective performance single value, the Functional Limitation Index (FLI), calculated as (VO2 peak/VO2 SM)/(VO2 SM/VO2 predicted).
​

I'm not sure what VO2 SM but I think it is VO2 Supramaximal, the VO2 measured at full exhaustion of the patient at the very end of the test.

 

[LJord]

For someone with ME/CFS what are the benefits of actually having a diagnosis? Doesn't it actually make getting diagnosed for other non-ME conditions that much harder, since everything gets blamed on the ME?

It is important to me in order to get treatment for anything at all (was labeled with Functional Neurologic Disorder and now everything is in my head). Also I am spending so much time fending off the endless referrals to physical therapy. Last week was prescribed by gastroenterologist. She claimed it would get rid of all my nausea and stomach pain. That and a phone app for meditation for anxiety because nausea=anxiety and anxiety=nausea? MD refused to answer my questions in the emergency room about a TIA because “You need to believe in the diagnosis for the treatment to work.” It was a TIA but once I was slapped with the FND label apparently I will never again be sick or need anything but exercise and therapy. Some of us really do need that diagnosis for safety. I am desperately trying not to become bedridden.

 

[Andy]

For someone with ME/CFS what are the benefits of actually having a diagnosis? Doesn't it actually make getting diagnosed for other non-ME conditions that much harder, since everything gets blamed on the ME?

Well, that is a huge generalisation for starters. While some people will have that experience, others will gain understanding about their condition from their diagnosis, and as noted in the post above it can be vital to some. It can also be important for 'political' reasons - if people who meet ME/CFS aren't counted then the size of the patient population falls, and the need to address the issue lessens (less pressure for appropriate treatment, or for research funding).

 

[Hutan]

They write:

We developed an objective performance single value, the Functional Limitation Index (FLI), calculated as (VO2 peak/VO2 SM)/(VO2 SM/VO2 predicted).
I'm not sure what VO2 SM but I think it is VO2 Supramaximal, the VO2 measured at full exhaustion of the patient at the very end of the test.

See my post above. There is a normal CPET to generate the VO2 peak, then a three minute rest sitting on the bike, and then another bout of cycling to exhaustion which generates the VO2 SM.

 

[ME/CFS Skeptic]

Thanks @Hutan

 

[Arnie Pye]

Well, that is a huge generalisation for starters.

Yes I know. As someone who hasn't been diagnosed with ME but who has apparently been diagnosed for the last 50 years with being a drug-seeker, an attention-seeker, a hypochondriac, being anxious and depressed, also FND and various other issues that nobody ever takes seriously I have been wondering whether an ME diagnosis would make things better or worse. I think I'd prefer not to be diagnosed with it if I can avoid it.

Things have improved slightly for me in recent years since I bought a copy of my GP records. I now have proof of some things I say when I mention my medical history. I take the most important pages with me for every appointment now, just in case they might turn out to be helpful during a consultation. I have also learned to treat some of my more common problems myself over the last 10 - 15 years so don't see doctors as often as I used to.