1. Patients launch $1.27 million crowdfunding campaign for ME/CFS gut microbiome study.
    Check out the website, Facebook and Twitter. Join in donate and spread the word!
Nitric oxide and its possible implication in ME/CFS (Part 2 of 2)
Andrew Gladman explores the current and historic hypotheses relating to nitric oxide problems in ME/CFS. This second article in a 2-Part series puts nitric oxide under the microscope and explores what it is, what it does and why it is so frequently discussed in the world of ME/CFS....
Discuss the article on the Forums.

1970 Birth Cohort. Childhood predictors of self reported CFS/ME in adults, Viner 2004

Discussion in 'Latest ME/CFS Research' started by oceanblue, Oct 13, 2011.

  1. oceanblue

    oceanblue Senior Member

    Messages:
    1,174
    Likes:
    343
    UK
    Childhood predictors of self reported chronic fatigue syndrome/myalgic encephalomyelitis in adults: national birth cohort study
    Viner & Hotopf 2004


    I'm going to be posting a summary of all 3 British Birth Cohorts (1946, 1958 and 1970) eventually but want to give each one its own thread too (see 1958 cohort thread)

    While I originally thought that the self-reported nature of CFS in these studies made them invalid, now I'm not so sure, not least because the prevalence figures they come up with look plausible (see post #3).

    This study concludes that a whole range of factors supposed to underpin CFS, eg chilhood psychological problems, were not risk factors for the illness:
    Esther12 likes this.
  2. oceanblue

    oceanblue Senior Member

    Messages:
    1,174
    Likes:
    343
    UK
    Abstract

    Objective To study childhood risk factors for chronic fatigue syndrome in adult life.

    Design Examination of data from the 1970 British birth cohort.

    Participants 16 567 babies born 5-11 April 1970, followed up at 5, 10, 16, and 29-30 years.

    Main outcome measures Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) identified by self report at age 30 years. Data from childhood from questionnaires given to parents and teachers. Maternal mental health assessed with the malaise inventory.

    Results 93 (0.8%, 95% confidence interval 0.7 to 1.0) of 11 261 participants reported ever having CFS/ME, and 48 (0.4%, 0.3 to 0.6) had the condition currently. Higher risk of CFS/ME was associated with having a limiting longstanding condition in childhood (odds ratio 2.3, 1.4 to 3.9), female sex (2.3, 1.4 to 2.6), and high social class in childhood (2.2, 1.4 to 3.5). Higher levels of exercise in childhood were associated with lower risk (0.5, 0.2 to 0.9). Maternal psychological disorder, psychological problems in childhood, birth weight, birth order, atopy, obesity, school absence, academic ability, and parental illness were not associated with risk of CFS/ME.

    Conclusions We identified no association between maternal or child psychological distress, academic ability, parental illness, atopy, or birth order and increasing risk of lifetime CFS/ME. Sedentary behaviour increased the risk.
    Esther12 likes this.
  3. oceanblue

    oceanblue Senior Member

    Messages:
    1,174
    Likes:
    343
    UK
    Commentary

    Birth cohorts are in some ways a dream tool for identifying risk factors for any illness, with risk factors giving clues about what might cause the illness.

    Method
    This study is based on a well-established birth cohort of 16,500 babies born in one week in Great Britain, with particpants followed up at ages 5, 10, 16 and 29-30 - mostly with questionnaires covering physical, psychological and social factors, but with some medical data too. "CFS/ME was identified by self report questionnaire completed at 30 years. Participants were asked whether they had ever had CFS/ME, whether they currently had CFS/ME, and at which age their condition developed".

    The self-report is the major weakness of this study. I don't think it renders the findings meaningless, but it does mean they need to be treated wtih a degree of caution. Interestingly, a recent UK study found that 31% of CFS cases identified by GPS did not meet CFS Fukuda criteria, according to an exhaustive questionnaire. (Presumably a good proportion of these cases would have had their diagnosis confirmed by a consultant.). I'm assuming that self-report would be less accurate than this, with maybe 40%-50% of cases not meeting Fukuda.

    Prevalence rates
    91 people out of 11,261 reported ever having CFS/ME, giving a 'lifetime' rate of 0.8%. The prevalence rate, ie those who currently had CFS/ME was 0.4%, which is in line with other estimates - one reason why I think the self-report data isn't meaningless.
    Debunking theories of ME
    The main aim of the study was to test numerous theories about what caused CFS against some data: risk factors examined included birth weight, atopy (allergies), obesity, childhood behavioural problems, childhood psychological problems and maternal psychological problems. Almost all of these were ruled out (or rather there was no evidence to support them), with only 2 possible risk factors identified:

    Childhood sedetary behaviour is a risk... or is it?
    High exercise levels had been suggested as a risk factor for ME but this study found evidence of the opposite: sedentary childhood behaviour (or rather never/rarely taking part in sports in spare time at age 10) was a risk factor for CFS. However, only 16% of CFS patients had been sedentary, compared with 8% of the main sample so sedentary behaviour could only explain 8% of all CFS cases. This is fairly typcial of cohort findings: even where a risk factor is identified, it usually only explains a small proportion of CFS cases ie is a bit of a side show.

    However, the sedentary finding is rather shaky:
    1. it's only just significant, with p=0.04. Arguably, the authors should have made some adjustment for multiple comparisons (more here) so the threshold for significance should probably have been lower, eg. p=0.01, not 0.05.
    2. If 40% of self-reported cases were misdiagnosed, that leaves far fewer 'true' cases, and the smaller numbers would almost certainly push the p value above 0.05 - and so to non-significance
    3. When different authors tried to replicate this finding in the 1958 cohort they couldn't: childhood sedentary behaviour was not a risk factor for CFS.

    None of which stopped newspaper headlines like "COUCH POTATOES MORE AT RISK OF ME" (info from Dolphin).

    So that just leaves:

    Childhood chronic illness is a risk factor for CFS
    Bizarrely, the authors didn't discuss this finding, even though it was more significant than the exercise one with p=0.003. Yet a link to prior childhood illness could be telling.

    Does this finding fall apart like the sedentary one above? Good question, reader. First, as the p value is smaller it's more likely to survive the loss of those misdiagnosed cases. I built a wee model and played with the numbers and it seems this finding is robust. It's still significant even if
    1. Only half of all cases are real CFS
    2. Up to 60% of the misdiagnosed cases are really due to other undiagnosed physical illnesses and 45% of those cases had chronic childhood illness
    ask me for more info if you're really interested, the main point is that you can shake this finding fairly hard and it holds good, though it will break if pushed hard enough.

    One note of caution on this finding (actually, two, as I'm not sure it's been replicated in other cohorts):
    Conclusion
    There's some evidence that childhood ill health is a risk factor for CFS, but no evidence for childhood or maternal psychopathology or a host of other factors being risk factors - and sedentary childhood behaviour doesn't cut it either.

    Thanks to those who commented on proto-versions of this, and especially to Dolphin who gave the tyres a good kicking.
    Esther12 likes this.
  4. Dolphin

    Dolphin Senior Member

    Messages:
    6,725
    Likes:
    5,565
    Thanks for another thorough analysis, oceanblue.

    To be exact, the one I recall was a general health internet website; but I can't remember all the coverage.

    Here's an example from the BBC:
    Inactive childhood 'can cause ME':
    http://news.bbc.co.uk/2/hi/health/3716576.stm
    (which also went with "Exercising may protect against ME").

    I think it would have been good if they had also checked data they had on individuals from the following item: "Teachers reports provided data on the usual number of hours of sport played by the child at school each week" (e.g. combine the two items, sport in and out of school). If somebody was active in school that would mean they weren't inactive.

    Also, for the item "Played >2 hours/week of sport at school at 10 year", the percentages for lifetime CFS/ME group were actually higher than everyone else (52% vs 44%) although this did not reach significance.
    Esther12 likes this.
  5. jen1177

    jen1177

    Messages:
    62
    Likes:
    23
    Arizona
    Two problems jump out at me from this study.
    1) I was born in 1970 but I wasn't officially diagnosed with CFS until I was 34. I didn't know what I had up until that point. I suspected, but really didn't know. I had all kinds of health problems for years before I became too sick to work but I never thought of them as CFS. I always kept thinking it was due to this or that and it would go away eventually. How many people in the study might have been in the same boat and not reported that they had CFS because they simply didn't know what it was? Or they hadn't developed it yet? These people turned 30 in 2000. I wonder how many have CFS now who said they didn't have it at the time that the study ended...
    2) They only used people who were born during a single week in April. I've read about studies that found that the time of year you were born in can affect your health. For example I remember hearing about a study that revealed that babies born in the spring have lower IQs (as adults) and they theorized that maybe it has something to do with pesticide exposure in the first few months of life or while in the womb during a certain stage of development. I think it could also be due to SAD. Seasonal Affective Disorder affecting the pregant mothers during the fall/winter which would be most of the gestation period for babies born in the spring. Or something else related to the colder months like the cold and flu season, the stress of the holidays, the unavailability of certain foods, lack of vitamin D, etc. Anyway...the CFS cohort study should have looked at people born throughout the year instead of just one week of it.
  6. oceanblue

    oceanblue Senior Member

    Messages:
    1,174
    Likes:
    343
    UK
    Good point about not ignoring all the exercise children had at school by combining the two. It might have led to more reliable findings and fewer silly headlines.
  7. oceanblue

    oceanblue Senior Member

    Messages:
    1,174
    Likes:
    343
    UK
    You're absolutely right that this study is likely to have missed plenty of cases of CFS such as your own, and to be fair the authors do acknowledge this. As the data was collected in 2000, there were likely to be more missed cases than there are now since diagnosis has improved a bit since, at least in the UK. Whether or not those missed cases would have been systematically different from the reported cases isn't clear. I'm not aware of a good reason why they would be different (and so change the findings), but it is another reason why the study findings can't be relied on as definitive.

    Although samples of births spread across the year would have been ideal, I'm not sure that using births from a single week would have made a difference in this case. As far as I'm aware, it doesn't generally make a difference in illnesses (I'm sure there are exceptions), and where it does make a difference the effect size is pretty small. I'm also not aware of anyone suggesting that time of year of birth is a factor in CFS. Do you know of any specific studies that would throw light on this issue?
  8. oceanblue

    oceanblue Senior Member

    Messages:
    1,174
    Likes:
    343
    UK
    Chronic illness finding not confirmed in 1946 cohort
    Good-time guy that I am, I'm now reading the 1946 cohort study, which found that chronic illness in childhood (this time age 0-15, as opposed to just at age 10) was not a significant predictor of CFS in adults. In the 1946 study, 18% of CFS patients had a reported chronic illness vs 16% of non-CFS cases.

    However, the 1946 study is under one third the size of the 1970 cohort (3,000 vs 9,600). In a statisitcally dubious play, I combined data for chronic illness from the 1946 and 1970 studies: the finding of chronic illness as a risk factor was still significant in the combined sample (Odd Ratio now slightly lower at 2.0 compared with 2.2 for 1970). note I'm not using the multivariate models correcting for gender etc used in the orginal papers, but these only seem to have a very small on the results.

    ETA: Ah, that negative finding on chronic illness looks dodgy as children with ill health were likely to drop out of the study by age 53 (when CFS data was collected for the 1946 cohort), making it unrepresentative:
    Esther12 likes this.
  9. Tony Mach

    Tony Mach Show me the evidence.

    Messages:
    146
    Likes:
    34
    Upper Palatinate, Bavaria
    I hate it when scholars write such misleading sentences in abstracts. Unless they have established a mechanism that A causes B (which I doubt), then sedentary behaviour is only associated with an increased risk of CFS/ME. Association does not imply causation, there could be an currently unknown underlying mechanism (infections, genetic risk, etc.) causing both sedentary behaviour and ME/CFS.

    The data gathered in epidemiologic studies can be really helpful, but the interpretations offered in epidemiologic papers have to be treated with utter caution, no matter what field of inquiry.
  10. jen1177

    jen1177

    Messages:
    62
    Likes:
    23
    Arizona
    I don't know of any specific studies that would link a higher risk of CFS with being born at certain times of the year. But that's my point. It's an unknown and it wasn't addressed in this study at all when it could have been. Just seems like a wasted opportunity to me.
  11. oceanblue

    oceanblue Senior Member

    Messages:
    1,174
    Likes:
    343
    UK
    The CFS element of this study was piggybacked in 2000 on a pre-existing birth cohort set up for altogether different reasons, so the authors had no opportunity to influence how the birth cohort was selected:
    It'll be the same for the CFI's planned epidmiology project which will piggyback on existing cohorts recruited for other purposes. Of course, these should have the huge advantage of proper CFS diagnosis and they are larger cohorts too, but they are less representative than the birth cohort (one cohort is of married female nurses and I think the male cohort is heavy on dentists). Even if the funds could be found for a dedicated cohort to study CFS, it would take many, many years before we saw any results.
  12. Esther12

    Esther12 Senior Member

    Messages:
    5,269
    Likes:
    5,480
    Thanks for all this. I keep reading these threads, finding them helpful, forgetting them, looking into the papers myself, finding the threads, and so on...

    I thought I'd add another example of media coverage:

    Sedentary kids at risk of chronic fatigue
    http://www.abc.net.au/science/news/health/HealthRepublish_1214353.htm

    I was also reading the BMJ comments and noticed that along with good ones from ME people, there was also one about the use of stats that I didn't fully follow, but could be of interest.

    http://www.bmj.com/rapid-response/2...ndependence-effect-modification-father’s-heal

See more popular forum discussions.

Share This Page