Quitting seems to have little effect on life-expectancy, as is shown in six of the
seven controlled trials which have been conducted to determine any such effect. The results
of the seventh are more complex.
This was a randomised five-year multifactorial prevention trial of
vascular disease (Miettinen, Huttunen, Naukkarinen et al., 1985). An
intervention group of 612 forty-eight year old businessmen, considered
to be at high risk of cardiovascular disease, were encouraged to
change their diet (particularly with regard to fat intake) to reduce
smoking and to take more exercise. Where blood pressure and serum
lipid levels did not fall sufficiently, the subjects were treated with
a variety of drugs, mainly diuretics and beta-blockers and probucol
and clofibrate. A similar group of 610 men was uncounselled and
untreated except that 15% of them received anti-hypertensive drugs.
After 5 years, most risk factors, including weight, blood pressure,
serum cholesterol and triglycerides and tobacco consumption had
improved significantly in the intervention group compared
with the control group.
At the end of 5 years, total mortality in the intervention group was
10/612 and in the control group 5/610, a non-significant difference.
There were no significant differences in mortality from specific
causes nor in morbidity except for non-fatal stroke which was more
common in the control group (8 versus 0). In brief,
improvement in lifestyle did not reduce CHD deaths or total deaths.
15 years later the story was very different.There were 45% more deaths
in the intervention group than in the control group (67v46). This was
largely due to more than twice as many cardiac deaths but there were
also 13 "violent" deaths compared to 1 in the control group.Quitting
may not have caused this disastrous result but it doesnt appear to
have helped.
There have been just 6 other similar trials, with happier results: no
change in total death rates, deaths due to cancer or deaths due to
cardiovascular disease. Quitting is probably less dangerous than this
Finnish study suggests
But one consequence of quitting, though rare, is well-known and
dangerous, ulcerative colitis. I give the example of a woman who found
that smoking eliminated all sign of the disease. When she tried quitting
the disease recurred.
This case is a clear reminder that people are all different. Quitting is
not good for eveyone and may be seriously harmful.
Installed 7 august 2006.
