Cigarette smoking
Cigarette smoking remains the most important cause of
preventable morbidity and early mortality. In 2000, there were an estimated 4.8
million premature deaths in the world attributable to smoking, 2.4 million in
developing countries and 2 million in industrialized countries. More than
three-quarters (3.8 million) of these deaths were in men. The leading causes of
death from smoking were cardiovascular diseases (1.7 million deaths), chronic
obstructive pulmonary disease (COPD) (1 million deaths), and lung cancer (0.9
million deaths). Nicotine is highly addictive, raises brain levels of dopamine,
and produces withdrawal symptoms on discontinuation. Cigar smoking has also
increased; there is also continued use of smokeless tobacco (chewing tobacco and
snuff), particularly among young people. Tobacco dependence may have a genetic
component.
Cigarettes are responsible for one in every five deaths in
the United States, yet smoking prevalence rates have been increasing among high
school and college students. Currently, 23% of US adults and 26% of US young
adults are smokers.
Smokers have twice the risk of fatal heart disease, 10
times the risk of lung cancer, and several times the risk of cancers of the
mouth, throat, esophagus, pancreas, kidney, bladder, and cervix; a twofold to
threefold higher incidence of stroke and peptic ulcers (which heal less well
than in nonsmokers); a twofold to fourfold greater risk of fractures of the hip,
wrist, and vertebrae; four times the risk of invasive pneumococcal disease; and
a twofold increase in cataracts. In the United States, over 90% of cases of COPD
occur among current or former smokers. Both active smoking and passive smoking
are associated with deterioration of the elastic properties of the aorta
(increasing the risk of aortic aneurysm) and with progression of carotid artery
atherosclerosis. Smoking has also been associated with increased risks of
leukemia, of colon and prostate cancers, of breast cancer among postmenopausal
women who are slow acetylators of N-acetyltransferase-2 enzymes,
osteoporosis, and Alzheimer's disease. In cancers of the head and neck, lung,
esophagus, and bladder, smoking is linked to mutations of the P53 gene,
the most common genetic change in human cancer. Patients with head and neck
cancer who continue to smoke during radiation therapy have lower rates of
response than those who do not smoke. Olfaction and taste are impaired in
smokers, and facial wrinkles are increased. Heavy smokers have a 2.5 greater
risk of age-related macular degeneration. Smokers die 5–8 years earlier than
never-smokers.
The children of smokers have lower birth weights, are more
likely to be mentally retarded, have more frequent respiratory infections and
less efficient pulmonary function, have a higher incidence of chronic ear
infections than children of nonsmokers, and are more likely to become smokers
themselves.
In addition, exposure to environmental tobacco smoke has
been shown to increase the risk of cervical cancer, lung cancer, invasive
pneumococcal disease, and heart disease; to promote endothelial damage and
platelet aggregation; and to increase urinary excretion of tobacco-specific lung
carcinogens. The incidence of breast cancer may be increased as well. Of
approximately 450,000 smoking-related deaths in the United States annually, as
many as 53,000 are attributable to environmental tobacco smoke.
Smoking cessation reduces the risks of death and of
myocardial infarction in people with coronary artery disease; reduces the rate
of death and acute myocardial infarction in patients who have undergone
percutaneous coronary revascularization; lessens the risk of stroke; slows the
rate of progression of carotid atherosclerosis; and is associated with
improvement of COPD symptoms. On average, women smokers who quit smoking by age
35 add about 3 years to their life expectancy, and men add more than 2 years to
theirs. Smoking cessation can increase life expectancy even for those who stop
after the age of 65.
Although tobacco use constitutes the most serious common
medical problem, it is undertreated. Almost 40% of smokers attempt to quit each
year, but only 4% are successful. Factors associated with successful cessation
include having a rule against smoking in the home, being older, and having
greater education. Persons whose physicians advise them to quit are 1.6 times as
likely to attempt quitting. Over 70% of smokers see a physician each year, but
only 20% of them receive any medical quitting advice or assistance.
Several effective interventions are available to promote smoking cessation,
including counseling, pharmacotherapy, and combinations of the two. The five
steps for helping smokers quit are summarized in Table 1–3. Common elements of
supportive smoking cessation treatments are reviewed in Table 1–4. A system
should be implemented to identify smokers, and advice to quit should be tailored
to the patient's level of readiness to change. Pharmacotherapy to reduce
cigarette consumption is ineffective in smokers who are unwilling or not ready
to quit. Conversely, all patients trying to quit should be offered
pharmacotherapy except those with medical contraindications, women who are
pregnant or breast-feeding, and adolescents.
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