CFS prevalence is grossly overestimated using Oxford criteria compared to CDC (Fukuda) criteria

[Dolphin]

CFS-Like subjects had no or minimal fatigue but substantial complaints on CFS ancillary criteria

This paper uses "CFS-like" in a different way to most or all of the epidemiological studies I've seen which use CFS-like to represent the group that fits CFS criteria but has not been properly medically assessed.

 

[Dolphin]

The Oxford criteria (‘Oxford’) define a case of CFS if mild to severe symptoms of fatigue, sleep disturbance, and myalgia are present [5]. The Oxford proxy was designated when all three items were present with mild or greater severities.

[5] Sharpe MC, Archard LC, Banatvala JE, et al. A report—chronic fatigue syndrome: guidelines for research. JR Soc Med. 1991;84(2):118–121.

This is very different to the actual Oxford definition. So I have no confidence in the figures quoted:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1293107/pdf/jrsocmed00127-0072.pdf

Chronic fatigue syndrome (CFS)

(a) A syndrome characterized by fatigue as the principal symptom.

(b) A syndrome of definite onset that is not life long.

(c) The fatigue is severe, disabling, and affects physical and mental functioning.

(d) The symptom of fatigue should have been present for a minimum of 6 months during which it was present for more than 50% of the time.

(e) Other symptoms may be present, particularly myalgia, mood and sleep disturbance.

(f) Certain patients should be excluded from the definition.

They include:

(i) Patients with established medical conditions known to produce chronic fatigue (eg severe anaemia). Such patients should be excluded whether the medical condition is diagnosed at presentation or only subsequently. All patients should have a history and physical examination performed by a competent physician.

(ii) Patients with a current diagnosis of schizophrenia, manic depressive illness, substance abuse, eating disorder or proven organic brain disease. Other psychiatric disorders (including depressive illness, anxiety disorders, and hyperventilation syndrome) are not necessarily reasons for exclusion.

 

[Dolphin]

Obvious limitations of relying solely on self-report of the nine Fukuda criteria items in these postal responses were the absence of clinical evaluations to confirm the presence or absence of each diagnostic criterion, inability to assess the full spectrum of symptoms from other definitions, e.g. Canadian criteria [8,9], and the inability to investigate the differential diagnosis of CFS and exclude inflammatory, psychiatric, and other medical conditions [7,27,28]. The HealthStyles survey included these definitional exclusions: arthritis-related symptoms, daily exercise for more than 30 minutes, and significant cardiovascular disease with transient ischemic attacks. It was not possible to assess the many other potential exclusions inherent in the differential diagnosis of CFS

Exclusions.

The Fukuda criteria and other more specified case definitions [6–9,27,28] have well-described directives for excluding medical illnesses that may explain fatigue and the remainder of the symptom cluster. Based on our questionnaire data, we used these three exclusions:

(1) HealthStyles arthritis scores plus CFSQ arthralgia severity scores that reached moderate or severe levels, given the medical implications of painful, red, hot, swollen joints with decreased range of motion and function as exclusionary of a CFS diagnosis;

(2) transient ischemic attacks which imply significant cardiovascular disease and strokes;

(3) agreement or strong agreement with the statement ‘I exercise 30 minutes every day’ in the HealthStyles questionnaire, which was considered exclusionary for reduced physical exertion and exertional exhaustion in CFS.

Other known CFS exclusions were not part of the HealthStyles survey.

 

[Dolphin]

The 2004 HealthStyles demographics were reported to be comparable to the 2003 U.S. Census estimates for age, race, sex, household size, and household income except for under-representation of the lowest education level (not a high school graduate) and over-representation of the lowest income (<$10,000) [30]. Stratified random sampling generated a list of 10,000 participants for the first wave ConsumerStyles survey mailing in May and June 2004. There were 6207 respondents.to assess the many other potential exclusions inherent in the differential diagnosis of CFS

 

[Dolphin]

CFSQ

The Fukuda CDC criteria [6] were scaled so subjects could grade their symptoms over the previous 6 months period as none (score = 0), trivial (score = 1), mild (score = 2), moderate (score = 3), or severe (score = 4) [22]. This scoring system allowed investigation of the levels of fatigue and each of the ancillary criteria that can distinguish control from CFS subjects. The sum of severity scores for the eight ancillary criteria was calculated as Sum8 (range 0–32). A significant threshold of Sum8 ≥ 14 was defined by receiver operating characteristics in 600 subjects from rhinitis, sinusitis, asthma, CFS, and other clinical trials (specificity = 0.93; sensitivity = 0.93; Cronbach’s alpha = 0.92) [22].

 

[Dolphin]

In addition, it is of value to determine if fatigue and other symptoms have continuous, normal distributions in the general population because ‘illness’ may be assigned to the tail of the normal curve distal to an arbitrary threshold, or may represent a separate and distinct pathophysiological entity with a bimodal distribution in health versus disease [20,21].

Sensible point it appears

Fatigue and Sum8 scores decreased in coordinated, exponential fashion so that a spline was evident in their distributions. This fan-shaped distribution suggested that fatigue and the other symptoms had continuous distributions in this population without obvious breakpoints. This emphasized the need for objective markers to reinforce the clinical diagnosis of moderate to severe fatigue plus ≥4 other complaints.

 

[Dolphin]

Removing the female subjects with exclusions from the CFS quadrant would have dramatically reduced the number and frequency of CFS subjects, but the Oxford criteria do not specifically exclude these subjects as is customary with Fukuda and other more rigorous definitions.

I'm not sure there is a sharp distinction on this issue between the Oxford definition and other definitions

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1293107/pdf/jrsocmed00127-0072.pdf

Chronic fatigue syndrome (CFS)

(a) A syndrome characterized by fatigue as the principal symptom.

(b) A syndrome of definite onset that is not life long.

(c) The fatigue is severe, disabling, and affects physical and mental functioning.

(d) The symptom of fatigue should have been present for a minimum of 6 months during which it was present for more than 50% of the time.

(e) Other symptoms may be present, particularly myalgia, mood and sleep disturbance.

(f) Certain patients should be excluded from the definition.

They include:

(i) Patients with established medical conditions known to produce chronic fatigue (eg severe anaemia). Such patients should be excluded whether the medical condition is diagnosed at presentation or only subsequently. All patients should have a history and physical examination performed by a competent physician.

(ii) Patients with a current diagnosis of schizophrenia, manic depressive illness, substance abuse, eating disorder or proven organic brain disease. Other psychiatric disorders (including depressive illness, anxiety disorders, and hyperventilation syndrome) are not necessarily reasons for exclusion.

 

[Dolphin]

Figure 2. Quadrant analysis of females (n = 1495). (A) The Oxford criteria permitted mild fatigue which skewed the putative CFS subjects into healthy control and CFS-Like quadrants. (B) The rigorous CDC criteria limited subject selection to the CFS quadrant with moderate or severe fatigue and the sum of the 8 ancillary criteria scores (Sum8) from 14 to 32.

Figure 3. Quadrant analysis of males (n = 2004). (A) The Oxford criteria permitted mild fatigue which skewed the putative CFS subjects into healthy control and CFS-Like quadrants. (B) The rigorous CDC criteria limited subject selection to the CFS quadrant with moderate or severe fatigue and the sum of the 8 ancillary criteria scores (Sum8) from 14 to 32.

It looks like these are the wrong way around i.e. the figure 2 wording applies to the graphs on page 8 and vice versa

 

[Dolphin]

The large proportion of subjects excluded by the small number of HealthStyles exclusionary conditions suggested that even more respondents may have had false-positive CFS status because of other medical or psychiatric comorbidities. The exclusion criteria were clearly incomplete for the conditions considered in the differential diagnosis of CFS. It was not feasible to inquire into all of the exclusions and differential diagnosis of CFS [27,28] in this on-line survey.

 

[BurnA]

This is very different to the actual Oxford definition. So I have no confidence in the figures quoted:

Can you clarify which figures you dont have confidence in?

 

[Dolphin]

Can you clarify which figures you dont have confidence in?

Any of the figures relating to the Oxford criteria.

 

[Dolphin]

Letter to the Editor
Simon Wessely & Michael Sharpe
To cite this article: Simon Wessely & Michael Sharpe (2017): Letter to the Editor, Fatigue:
Biomedicine, Health & Behavior, DOI: 10.1080/21641846.2017.1364148
To link to this article: http://dx.doi.org/10.1080/21641846.2017.1364148

I am no fan of the Oxford criteria. Nor am I a fan of the work by Simon Wessely and Michael Sharpe on CFS* but I think their letter is fair for the reasons I have already given in this thread.

*I don't know much about other work