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Public Health practitioners are irritating people, or so I
am led to believe, mostly by my wife. The BBC News makes a seemingly harmless comment
about the perils or failings of society and we immediately cast
doubt upon its veracity, asking for evidence.
The nice thing about evidence is
that it so often manages to throw out people’s long-cherished
beliefs. One that is quoted an awful lot in relation to our latest
medical fashion, childhood obesity, is that children are being made
into couch potatoes because the wicked government have forced
bankrupt schools to sell off all of their playing fields for Toytown
housing and therefore the kids lie about all day. Or that
hyper-neurotic parents, frightened by the media into believing that
every second passer-by is a child rapist insists on driving the 4x4
200 yards to school, depriving the child of that much-needed
cycle/sprint/saunter, and incidentally, killing quite a lot of
pedestrians. Or maybe poor terrified teachers, battered by the needs
to keep up the SATS figures, have dumped games from the curriculum
in favour of riting.
But the kids will have none of it.
A survey of children at primary schools in England, published in the
BMJ, found a marked decline in timetabled physical education between
1994 and 1999. But another study using accelerometers to measure
the impact of timetabled physical education at school on overall
physical activity in children showed that the myth may be wrong.
This study compared three schools;
one a private preparatory school that had extensive facilities and
nine hours a week of physical education in the curriculum. The
second, a village school awarded Activemark gold status for its
physical activity, offered over two hours of timetabled physical
education a week; the third, an inner city school, offered less than
two hours.
The first school recorded the most
activity in school time but this was barely twice that of pupils in
the second or third schools despite more than four times the amount
of physical education on the timetable. The total physical activity
between the schools was similar because children in the second and
third school did correspondingly more activity out of school.
Another nice example of undoing a
myth was a series of interesting studies by Ferrari. This work
contributes to the debate about whiplash—whether it is an injury or
a disease, partly, at least, promoted by the possibility of
obtaining financial rewards against the person to blame for the
vehicle accident.
He compared the frequency and
nature of expected 'whiplash' symptoms in Lithuania and Greece with
that in Canada. He carried out symptom checklists in which people
were asked to imagine having suffered a neck sprain with no loss of
consciousness in a motor vehicle accident, and to check which, of a
variety of symptoms, they would expect might arise from the injury.
They were also asked to say the period of time the symptoms would be
likely to persist.
In all three groups, the pattern
of symptoms anticipated closely resembled the acute symptoms
commonly reported by accident victims with acute neck sprain, but
while up to 50% of Canadians anticipated symptoms to last months or
years, very few Lithuanian or Greek subjects selected any symptoms
as likely to persist.
The authors concluded that in
Lithuania and Greece, despite the documented occurrence of neck
sprain symptoms in about half of the subjects following motor
vehicle accidents, there is a very low rate of expectation of any
long term effect from the injury. It seems possible that the
cultural tendency to sue for whiplash injury in Canada, not known in
the other countries, may be perpetrating the myth of the disease.
 My own attempt to contribute to
these debates over the years has been around the mythology relating
to old age. This is a particularly perverse mythology, contributed
to by old people as much as younger people and their doctors, and
riddled with victim-blaming, notably by successive governments when
older people are assumed to be defiling the sanctity of the ‘acute
bed’.
It is assumed that the prevalence of elderly people, a
measure of our success as health advocates, must be to blame for the
lack of beds in hospital. It is curious that this should be seen as
the main cause when one looks at the number of beds available and
the number of admissions to those beds over the past 50 years.
I like to extrapolate the lines
another 25 years and try to work out how 25 million patients are
going to get into the remaining bed, elderly or not. Though the way
the government is attacking the planning of the NHS, I would not be
surprised.
But the subject of myth cannot
really be left without the ultimate reality-check for ourselves in
public health; is our work as objective as we suppose? In a study
looking into this question three assessors rated 160 Cochrane
systematic reviews. Disagreements were resolved by discussion to
arrive at a score for each review. The reviews' authors were given
the same categories.
Agreement between two assessors was 0.68 and
0.72, and between readers and assessors, 0.32. The authors state
‘These disagreements suggested a degree of subjective interpretation
involved in systematic reviews. Where patterns of disagreement
emerged between authors and readers, authors tended to be more
optimistic in their conclusions than the readers’. The good news is
that we are worried by the study and determined to do something
about it.
A nice spurious association
between mortality as a result of treatment for myeloid leukaemia and
star sign has recently been published
here, showing the problems of looking at the stats with a desire
to find something, not with an open mind. Poor statistics, they are
not to blame, they are just very innocent and easily led astray by
wicked journalists, politicians and, even occasionally,
statisticians.
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