A new study attempting to model the future risk of coronary heart
disease (CHD) and its price, based on past and current exposure to
second-hand smoke, has found that although "passive" smoking will
continue to have a clinical and economic impact, this burden will
likely be lower than it has been in the past [1].

Dr James M Lightwood (University of California, San Francisco) and
colleagues, writing in the American Journal of Preventive Medicine,
explain that the aim of their study was to recalibrate the CHD
policy model used to predict the impact of second-hand smoke, given
that exposures have been declining over the years, in part related
to legislation limiting smoking in public spaces. Using both high
and low estimates of the relative risk of CHD associated with second-
hand smoke exposure, the authors calculated that passive smoking,
between 1999 and 2004, likely caused 21 800 to 75 100 deaths from
CHD, and 38 100 to 12 8900 MIs. Treatment costs per year ranged from
$1.8 billion to $6.0 billion, they estimated.

The revised CHD policy model used by Lightwood et al combines data
from the US Census, Framingham Heart Study (FHS), Framingham
Offspring Study (FOS), National Health and Nutrition Evaluation
Survey (NHANES), National Hospital Discharge Survey (NHDS), and
National Health Interview Survey from 2000 to create a computer
simulation of CHD incidence, prevalence, mortality, and cost among
US adults older than 35 years. From the model, the authors estimate
that active smoking declined in a linear fashion, by about 0.19
percentage points per year, from 1999 through 2008; over roughly the
same period, exposure to second-hand smoke has decreased by 25% to
40%, which has translated into a 25% to 30% reduction in the CHD
burden.

Although the reduced exposure and CHD consequences are encouraging,
Lightwood emphasizes that physicians need to keep in mind that
smoking and exposure to second-hand smoke are two of the few fully
preventable causes of death, yet people continue to smoke and be
exposed. In Lightwood et al's model, an estimated 25% to 40% of the
population aged 35 to 84 is exposed to cigarette smoke and its
inherent cardiovascular risk.

"For cardiologists, this study shows that even when you take into
account deaths from other causes, and the fact that if you survive
passive smoking sooner or later you're going to die from something,
the burden of passive smoking is still large, both in terms of
events and money spent," Lightwood told heartwire. "I would hope
that physicians and healthcare professionals in general, whether
cardiologists or not, would pay a lot of attention to this, because
depending on what group you're looking at, we still have a sizeable
population exposed to passive smoking."

He also pointed out that cardiovascular effects of smoking include
both acute and chronic effects on the heart and vasculature. "In our
literature review, we had to figure out how much passive smoking
affects heart attack and arrest, and how much is angina. How much
does it just kill you right away with a major event, and how much
does it slowly damage your arteries? And it looks like almost all of
the damage, and all of the risk, goes right to major events like
heart attack, ACS, and cardiac arrest. So there are a lot of people
who basically just keel over from this; that's where the evidence
is. So regardless of whether you're a cardiologist or not, if you're
worried about patients, passive smoking is something you're going to
want to stop."


Lightwood JM, Coxon PG, Bibbins-Domingo K, et al. Coronary heart
disease attributable to passive smoking. Am J Prev Med 2009;
DOI:10.1016/j.amepre.2008.09.030. Available at: http://www.ajpm-
online.net.