Incidence of ME/cfs in a large prospective cohort of U.S

Kati

Patient in training
Messages
5,497
Likes
19,641
Incidence of myalgic encephalomyelitis/chronic fatigue syndrome in a large prospective cohort of U.S. nurses

http://www.tandfonline.com/doi/full/10.1080/21641846.2017.1323576

Author: Natalia Palacios (Harvard Public Health), Kathryn Fitzgerald (John Hopkins), Anthony Komaroff (Harvard School of Medicine), Alberto Ascherio (Harvard School of Public Health)

ABSTRACT

Background: The incidence of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), the rates of both under-diagnosis and over-diagnosis, and the nature of the onset of the condition have not been assessed in large studies of health professionals.

Purpose: To determine the cumulative incidence of ME/CFS in a large population of health professionals, to examine the nature of the onset of the illness, and to estimate the frequency of both over-diagnosis and under-diagnosis of ME/CFS.

Methods: We sent an email questionnaire to participants in the Nurses’ Health Study II (NHS II), a large prospective cohort of female nurses. Forty-two thousand three hundred and ninety-four women completed the questionnaire, which included the 1994 Centers for Disease Control and Prevention (CDC) criteria for ME/CFS.

Results: One-hundred and two women (240 per 100,000 surveyed) developed an illness that met criteria for ME/CFS between 1989 and 2009. The onset of ME/CFS was gradual in 40.6%, sudden (following flu-like illness or other precipitating events) in 18.8%, followed emotional or physical trauma in 32.3%, and was uncertain in the rest. Under-diagnosis was common: only 15 (15%) of the women who met criteria for ME/CFS reported having been diagnosed. Over-diagnosis also was common: four times as many subjects had been diagnosed with ME/CFS by community doctors as actually met criteria. The distribution of symptoms was not different in comparing cases with a sudden onset to those with a gradual onset.

Conclusions: In this large cohort of female nurses, we found a low cumulative incidence of ME/CFS. Over-diagnosis and under-diagnosis were high, even in this medically sophisticated population.
 
Messages
5,256
Likes
32,022
An interesting study. The great advantage is that the cohort was set up completely independently of any intention to study ME/CFS. Being just nurses might skew things but what is to me significant is that the headline rate of 0.2% (not strictly a prevalence but in the ball park) is very close to the rate obtained in the UK by Nacul et al. The much higher rate diagnosed by community physicians is also consistent with the much higher rate obtained with looser criteria. It looks as if we may have a pretty stable concept of ME/CFS. It also looks as if loose criteria may really be as big a problem as has been feared.
 

Kati

Patient in training
Messages
5,497
Likes
19,641
An interesting study. The great advantage is that the cohort was set up completely independently of any intention to study ME/CFS. Being just nurses might skew things but what is to me significant is that the headline rate of 0.2% (not strictly a prevalence but in the ball park) is very close to the rate obtained in the UK by Nacul et al. The much higher rate diagnosed by community physicians is also consistent with the much higher rate obtained with looser criteria. It looks as if we may have a pretty stable concept of ME/CFS. It also looks as if loose criteria may really be as big a problem as has been feared.
i belong to that ongoing Nurses Health study cohort, though may not have been included in this particular study. the questions they ask at this time (and they ask several times) what you ate when you were a child, what is your waist circumference, where you lived from birth and on, whether you were drinking well water or tap, that kind of stuff. I suspect that in a few years time they will come up with 'there is a link between incidence of type 2 diabetes and not eating carrots as a child'. :bang-head:
 
Last edited:
Messages
5,256
Likes
32,022
i belong to that ongoing Nurses Health study cohort, though may not have been included in this particular study. the questions they ask at this time (and they ask several times) what you ate when you were a child, what is your waist circumference, where you lived from birth and on, whether you were drinking well water or tap, that kind of stuff. I suspect that in a few years time they will come up with 'there is a link between incidence of type 2 diabetes and not eating carrots as a child'. :bang-head:
I wouldn't blame the people who set up the cohort for what other people are now asking, necessarily. And I am sure there is a correlation between not eating carrots and type 2 diabetes. No child will eat carrots if there is KFC and chips followed by ice-cream available will they? Not that the carrots are good for you, just that the KFC and ice-cream is bad I guess. It wasn't your fault anyway!!

I have seen some useful data come out of the cohort. The questionnaires may not have been ideal here but at least the answer seems to tie in with what we already have.
 

daisybell

Senior Member
Messages
1,613
Likes
7,388
Location
New Zealand
I would love to know how many of those 400 diagnosed wrongly have improved following some kind of intervention... it feels to me as though this is the biggest problem we face - that far more people are diagnosed than should be, and I'd like to know how much more likely they are to recover.
Until that mess is sorted, I can't see the perception of our illness changing significantly.

Interesting stuff!
 

BurnA

Senior Member
Messages
2,087
Likes
9,787
Sudden onset following flu like illness in 18.8%, seems low to me.
Emotional or physical trauma in 32.2%, pity these were lumped together but seems high to me. I can't quote other sources so I am just going by what I think more than what I know.

0.2% seems consistent though.
 

Barry53

Senior Member
Messages
2,391
Likes
13,649
Location
UK
My wife is the one with ME, and fits with most of the symptoms, including PEM. She would I'm sure fit within the 0.2%.

More than 20 years ago, I went through a quite a few years of very disturbing tiredness (I use the word deliberately, and not "fatigue"), to the point I even fell asleep at work once. Felt very spaced out and muddle headed a lot of the time, which I found distinctly worrying. Typically woke up after a full night's sleep feeling as if I'd never slept, drugged almost. Never bad enough to go to a doctor with, as I saw it anyway. I thought it was maybe a mild recurrence of glandular fever, which I'd had when I was 18. Looking back now, I suspect that some doctors might well have mistakenly labelled me with "CFS/ME", but I am absolutely certain I never have had ME. I have the clear comparison of my symptoms versus those of my wife, and I never ever had PEM, nor really disabling fatigue at all ... disabling tiredness but not fatigue. I also later developed IBS.

Why am I bothering to recount this? Well, there came a point where the colleague I used to car-share our daily commute with retired, and we had always used his car. I decided in the end to have a bit of a commute makeover, and cycle/train to/from work. About 14 miles hilly cycle riding each day. Bit scary at first given the IBS, but I only ever had to return home in a panic once! But the thing is, after around 5 or 6 months of this it suddenly struck me - I no longer had the IBS, nor the tiredness or fuzzy headiness. For me the routine exercise day in day out, did me a power of good. But my point is: I never had ME, but might very well have been misdiagnosed with it if I had sought medical help. I would then have ended up as a flawed statistic purporting exercise being helpful for ME! And at that time, I would have known no different. My guess, given my complete lack of medical knowledge, was that my previously sedentary lifestyle maybe led to some build up of toxins in me, and that the consistent routine exercise maybe helped my body rid itself of them; pure guess though. But it's how it felt to me.

As an adjunct to this, one slightly screwy symptom, but which I am absolutely positive about, is that apples used to exacerbate the fuzzy headed symptom considerably. And yes, my observations did account for the fact there could typically be a day or two's delay between cause and effect. After my exercise benefits had all kicked in, this ceased, and I could eat apples to my heart's content with no ill effects. One thing I did wonder (but this I fully concede is highly nebulous thinking) is that when I was recuperating from my bout of glandular fever, the doctor advised me to eat plenty of apples. Given how I love apples, I went at it with a will - 2 pounds of apples a day for several weeks! I retrospectively wondered if I had inadvertently overdone it on the apples whilst recovering.

EDIT: I forgot to mention that along with the fuzzy headed feeling, I did also feel vaguely unwell, slightly faint. The sort of sensation you get when you first think "Oh, is this a bug coming on?". But I never had any sense of it being exercise related. This was definitely part and parcel of the apples issue. Also forgot to mention that it would typically take a couple of weeks after stopping eating apples (including as an ingredient), before I would feel clearer headed again.
 
Last edited:

Kati

Patient in training
Messages
5,497
Likes
19,641
I wouldn't blame the people who set up the cohort for what other people are now asking, necessarily. And I am sure there is a correlation between not eating carrots and type 2 diabetes. No child will eat carrots if there is KFC and chips followed by ice-cream available will they? Not that the carrots are good for you, just that the KFC and ice-cream is bad I guess. It wasn't your fault anyway!!

I have seen some useful data come out of the cohort. The questionnaires may not have been ideal here but at least the answer seems to tie in with what we already have.
Well someone could well not eat carrots but eat broccoli, cabbage and asparagus. The one thing about these studies is they seem to attract media attention in the wrong ways (ex:red wine protects against heart attack).
 

Forbin

Senior Member
Messages
966
Likes
4,051
Am I correct in assuming that this incidence rate of 0.24% does not necessarily contradict Jason's higher prevalence rate of 0.42% ?

This study suggests that about 1 in 417 US female nurses contracted ME in a 20 year period, whereas Jason's work suggests that the number of US adults who currently have the disease is about 1 in 238 (about 75% greater).

The higher prevalence compared to incidence rate would seem to be consistent with a disease of long duration and low recovery rate.

[ Also, since nurses seem to have had a high incidence rate in the historical outbreaks, it seems possible that their occupation may carry a higher incidence rate than that of the general population. ]
 
Last edited:

Barry53

Senior Member
Messages
2,391
Likes
13,649
Location
UK
And I am sure there is a correlation between not eating carrots and type 2 diabetes. No child will eat carrots if there is KFC and chips followed by ice-cream available will they? Not that the carrots are good for you, just that the KFC and ice-cream is bad I guess. It wasn't your fault anyway!!
Nice example of the confusion/conflation of correlation versus causation. I appreciate the above is simply illustrative, but it is not so far removed from the data-abuse manipulations the BPS-brigade seem to indulge in.
 
Messages
5,902
Likes
12,704
Location
South Australia
The study is interesting, but has clear methodological deficiencies (which fortunately, are explicitly stated in the manuscript).

Given the gender bias of CFS, the overall population estimate would of course be lower than the figure quoted above. (and also consider the age range targeted - eg this study would exclude those who become ill as children, those above working age etc).

Of these women, 15 (15%) reported having been diagnosed with ME/CFS during the above time period. On the other hand, a diagnosis of ME/CFS was also reported by 395 women who did not meet the CDC criteria for ME/CFS.
The nature of the onset of the illness was quite variable. Table 1 shows the distribution of participant answers to this question. Among the subjects with ME/CFS, 40.6% reported that their fatigue had begun gradually; 19.8% reported that their fatigue had begun after an emotional trauma; 18.8% reported that their fatigue had begun suddenly following a flu-like illness; 12.9% reported that their fatigue had begun after a physical trauma or injury; 7.9% could not remember the circumstances of the onset of their fatigue; and 1.0% reported a sudden onset with no particular precipitating factor.
However, sore throat, neck or axillary adenopathy, and headaches were reported by fewer than half of the cases. Of particular interest, post-exertional malaise was not reported by 34% of the cases. This is of interest because the Institute of Medicine report [1] placed special emphasis on post-exertional malaise in proposing a new case definition for ME/CFS.
They did not undergo a physical examination nor laboratory testing to exclude the presence of other causes of fatigue, thus potentially affecting our estimate of the incidence of ME/CFS in this population.
Another limitation is the possibility that nurses with ME/CFS could have dropped out of the cohort more frequently than nurses without ME/CFS, reducing our estimate of incidence.
The fact that many women were reporting a diagnosis, yet did not meet the CDC criteria suggests that either the criteria used in the UK, specifically the commonly used Oxford or "NICE" criterias are too non-specific. Or that physicians in the UK lack the knowledge and skill to apply the criteria correctly.
 
Last edited:

Denise

Senior Member
Messages
1,095
Likes
3,431
The study is interesting, but has clear methodological deficiencies (which fortunately, are explicitly stated in the manuscript).

Given the gender bias of CFS, the overall population estimate would of course be lower than the figure quoted above. (and also consider the age range targeted - eg this study would exclude those who become ill as children, those above working age etc).









The fact that many women were reporting a diagnosis, yet did not meet the CDC criteria suggests that either the criteria used in the UK, specifically the commonly used Oxford or "NICE" criterias are too non-specific. Or that physicians in the UK lack the knowledge and skill to apply the criteria correctly.
@Snow Leopard - good point that this is a select population. Female, educated, healthcare professionals.
To clarify - NHS in this paper refers to Nurses' Health Study .
 

Kati

Patient in training
Messages
5,497
Likes
19,641
It is a nurses cohort. All nurses are invited to enter the cohort. We get questionnaires every now and then (4 times a year or so to keep in touch). As I said before, the questions that are being asked currently pertains to how, where you lived as a child.

I vaguely remember answering questions on diseases but I do not remember answering a fukuda- like questionnaire.
It needs to be noted that it is a self-report kind of study, all electronic. I do not know if this current study contacted the patients who said they had CFS by phone.

ETA: full text here http://sci-hub.io/saveme/4554/10.1080@21641846.2017.1323576.pdf
 
Last edited:
Messages
1,176
Likes
3,922
Location
Bristol
The proportion misdiagnosed is alarming. Also that a third of those they say do fit criteria don't get PEM, so we'd probably say they don't have ME.

So that's something like 433 nurses diagnosed with ME/CFS who don't have it, compared to around 66 who actually have ME...

What is particularly concerning is these wrongly diagnosed people may well have something that is already treatable. Plus these are healthcare workers who haven't spotted that they're misdiagnosed.

I wonder how these proportions would compare with Phoenix Rising? It doesn't seem plausible that most of us are misdiagnosed, but are we better informed on average than nurses diagnosed with ME/CFS?

I am fairly sure I do have ME (I meet all the various case definitions, get 24hr delayed PEM, had classic glandular fever trigger), but I'm also looking into Periodic Paralysis (more as a potential comorbidity) and I was surprised to see that has something very like PEM.
 

Manganus

Senior Member
Messages
166
Likes
403
Location
Canary islands
What is particularly concerning is these wrongly diagnosed people may well have something that is already treatable. Plus these are healthcare workers who haven't spotted that they're misdiagnosed.
Two points:
  1. It's likely that plenty of healthcare workers realize they are misdiagnosed. Unless I missed it, the paper doesn't say anything about that. But although healthcare workers, and also former healthcare workers, might have personal contacts with certain competent physicians - as a rule, we have no way to make doctors taking us more seriously than they take other patients with difficult symptoms.
  2. When you work in the health care, you internalize the common conceptions and misconceptions.
 

pattismith

Senior Member
Messages
3,489
Likes
6,864
Thank you for giving me the link to this study.
(I couldn't reach it, I suppose because you removed the "nurses" from the title...)

I was hit by the underdiagnosed statistics (Under-diagnosis was common: only 15 (15%) of the women who met criteria for ME/CFS reported having been diagnosed.)

As a non diagnosed CFS woman myself, I wonder if (like in many diseases),
women are more often underdiagnosed than men.
A gradual onset may also makes it more difficult and longer for a diagnosis...

Do we have such statistics among men cohorts?