First published by Spectator Health in January 2016
Sally Davies, the Chief Medical Officer, recently described the
belief that moderate alcohol consumption was good for the heart as an
‘old wives’ tale’. This was the culmination of a long-running campaign
within a section of the public health lobby to cast doubt on the large
body of evidence showing lower rates of heart disease and lower rates of
mortality among moderate drinkers. A report from researchers at
Sheffield University, released on the same day, claimed that the health
benefits of drinking were ‘disputed’ and the subject of ‘substantial
debate’.
It is difficult to imagine any amount of evidence persuading Sally
Davies that moderate drinking is healthy. The protective effect of
alcohol on the heart was first observed in 1926 and countless studies
from all around the world have confirmed it in the 90 years since. It
seems that Davies places a much greater burden of proof on scientists
who find a positive effect from drinking than on those who find a
negative effect. This can be illustrated by looking at two light bulb
moments in the career of the legendary epidemiologist, Richard Doll.
In 1950, Doll, along with Austin Bradford Hill, published the first epidemiological study showing
a link between cigarette smoking and lung cancer. Many people were
sceptical and potential flaws were quickly flagged up. The study had
been limited to hospital patients in and around London, the vast
majority of whom were smokers. In response, Doll and Hill got back to
work and published a further study in 1952 which expanded its geographic reach. It came to the same conclusion.
Doll then initiated a prospective study which tracked the health of
smoking and non-smoking doctors around the UK. When the first full
findings were published in 1956 they once again showed a clear link between smoking and lung cancer risk.
In the meantime, researchers from other parts of the world conducted
similar epidemiological studies with similar results. Gradually, it came
to be accepted that the relationship was causal — smoking caused lung
cancer.
Scepticism did not disappear overnight but as the years went by it
was increasingly confined to the vested interests of tobacco companies
and to maverick scientists who put forward alternative theories which
might explain the statistical association between smoking and ill
health. For example, the great statistician Ronald Fisher suggested that
the early stages of lung cancer gave people the urge to smoke.
Implausible though they were, such theories were not rejected out of
hand but were subject to rigorous empirical testing until they were
found wanting.
By 1976, when Richard Doll and Richard Peto published another edition of the doctors’ study,
there was a wealth of evidence to support ‘the smoking theory’ (as it
had been known) and there was a broad scientific consensus that the
relationship between cigarettes and cancer was causal and proven.
Alternative explanations had been tested and debunked.
Some people still refused to believe it, but they were a dwindling
minority. The sceptics now became ‘merchants of doubt’, cherry-picking
individual studies that seemed to undermine the larger body of evidence
and raising spurious objections that had already been addressed in the
scientific literature. Some demanded an impossible burden of proof by
calling for randomised control trials which could not possibly be
conducted even if it were ethical (which it would not be). Others said
they would not believe smoking caused lung cancer until the exact
biological mechanism by which it did so was identified.
Then, in 1994, Doll (now Sir Richard Doll) identified another statistical association in the data from the doctors’ study. In a study
published with Richard Peto, he found that all-cause mortality was
lower among moderate drinkers than it was among non-drinkers and heavy
drinkers. It was not the first time such an association had been
observed but some people were doubtful — not about the risks of heavy
drinking but about the apparent risks of not drinking. Alternative
explanations were again put forward, notably the possibility that some
non-drinkers may have been former drinkers who had put their health at
risk and were therefore at greater risk of premature mortality. This
came to be known as the ‘sick quitter’ hypothesis.
As he had done when conducting research into smoking, Doll addressed
his critics by carrying out a new epidemiological study. He published an
article
in 1997 looking at the question of causality which rejected the
hypothesis that the association was due to confounding factors. Then, a
few months before his death in 2005, he published a study
based on 23 years of data which replicated the results of his previous
studies while disproving the sick quitter hypothesis by comparing
lifelong non-drinkers with moderate drinkers. The latter had lower rates
of heart disease and lower risk of premature mortality.
By this time, Doll concluded: ‘That the inverse relationship between
ischemic heart disease and the consumption of small or moderate amounts
of alcohol is, for the most part, causal should, I believe, now be
regarded as proved’. A Department of Health working group appeared to
agree, noting: ‘All the evidence we have received confirms that the
relationship between all-cause mortality and alcohol consumption follows
a J-shaped curve. Non-drinkers have higher all-cause mortality than
light and moderate drinkers’.
Doll was not alone in this research. As with the smoking-lung cancer
finding, he was supported by researchers from around the world whose
studies came to the same conclusion: moderate drinking lowered the risk
of all-cause mortality and of heart disease in particular. In 2006, a meta-analysis
of 34 prospective studies concluded that men who drank up to four
drinks a day and women who drank up to two drinks a day had a lower
mortality risk than those who did not drink at all. The sick quitter
hypothesis was repeatedly tested and found wanting. The protective
effect on the heart was repeatedly shown to be real and not the result
of unhealthy former drinks in the non-drinking group.
As before, a noisy minority continued to deny these findings. They
insisted that the biological pathways were unproven, though plausible
pathways had been identified. They made generic criticisms of
epidemiology that could apply to any observational research, though they
never made them of studies which showed negative effects from drinking.
Above all, they treated the sick quitter hypothesis as an unanswered
question, never acknowledging that it had been tested extensively.
Decades after the evidence on moderate alcohol consumption had first
been identified, those who refused to accept it were embroiled in a
campaign of doubt and denial similar to what Doll had witnessed in the
mid-20th century, but this time the naysayers were on the inside of the
public health establishment, albeit in its neo-temperance wing. For
years, they chipped away at the science, repeating the same old
criticisms, cherry-picking studies and demanding an impossible burden of
proof from researchers. They received a sympathetic hearing from their
public health colleagues who had long struggled with the nuanced message
that heavy drinking was bad while moderate drinking was good.
Preferring a simple, clear, strong message that alcohol was dangerous,
they were similarly inclined to dismiss or downplay the epidemiology.
Taken as a whole, the evidence was too strong to overcome, but so
long as the critics persisted the evidence would, by definition, be
‘disputed’ and there would still be a ‘debate’. That was the line taken
by the authors of the Sheffield University report when the Chief Medical
Officer commissioned fresh research for the new drinking guidelines. In
the 20 years since the Department of Health’s working group had
concluded that epidemiological studies ‘strongly indicate a direct
causal relationship’ between moderate drinking and cardiovascular
health, the evidence had grown and become stronger, but anyone reading
the Sheffield report would have got the impression it was on the brink
of falling apart. Anyone listening to the Chief Medical Officer on the Today programme would have assumed it had already fallen apart. ‘An old wives’ tale’, she said. And with that, the job was done.
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