19 August 2009
MedWire News: Users of smokeless tobacco products face a small but
significantly increased risk for fatal myocardial infarction (MI) and stroke,
results of meta-analysis demonstrate.
“If the association is real, its public health and clinical implications might
be substantial, despite the fact that the magnitude of the excess risk is
small,” say Paolo Boffetta and Kurt Straif from the International Agency for
Research on Cancer, Lyon, France.
The study used data from the USA and Sweden, two countries that have seen a rise
in smokeless tobacco use in the past few decades, particularly among people
younger than 40 years.
“These products have been proposed as an alternative to cigarettes and other
smoking products under the claim of a smaller, or negligible, risk to health,”
the researchers add in the British Medical Journal.
To examine this claim Boffetta and Straif looked for studies that provided a
quantitative estimate of the association between ever use of smokeless tobacco
products and incidence or mortality of MI and stroke.
As active smoking could potentially confound the results the researchers
restricted the meta-analysis to studies of never smokers. They also excluded
data from Asia since the smokeless tobacco products consumed there are quite
different from those used in Europe and North America.
The authors found 11 suitable studies, all from either Sweden or the USA,
including nearly 7000 participants, almost exclusively male.
They report that current smokers faced a significant 17% increased relative risk
for fatal MI and a 28% increased relative risk for fatal stroke, compared with
those who had never used tobacco.
The association did not reach statistical significance when considering the risk
for nonfatal stroke or MI.
The researchers also calculated that the proportion of deaths from MI
attributable to use of smokeless tobacco products was 0.5% in the USA and 5.6%
in Sweden. The corresponding figures for deaths from stroke were 1.7% and 5.4%,
respectively.
Boffetta and Straif note that previous studies of smokeless tobacco show a short
term increase in blood pressure and heart rate but inconclusive effects on
hypertension and long term CV measures.
“Future research should aim to clarify the mechanisms of effect of smokeless
tobacco products on deaths from CV,” they say.
BMJ
2009; Advance online publication