McKeown17 has classified the ''causes" of health and disease into four types of components: (1) genetic, (2) environmental, (3) behavioral, and (4) preventive. The 1979 Department of Health, Education, and Welfare publication Healthy People12 accepted his concept and went on to estimate that, of all potentially preventable disease, about 10 percent could be forestalled by genetic counseling and prenatal diagnosis, 30 percent by means of environmental interventions, and another 10 percent by the vigorous application of preventive and other health services. The report also estimated that approximately 50 percent of all preventable illness could be avoided by modifying one or more of those health factors (e.g., diet, physical activity, cigarette smoking, alcohol consumption) that exert such profound effects on health. Although some might rank diet as first among these factors, cigarette smoking is usually ranked as the behavior that can be most efficiently modified to reduce the risk of disease and untimely death. For instance, in the United States, current estimates attribute about 21 percent of coronary heart disease, 82 percent of chronic obstructive lung disease, and more than 90 percent of cancer to cigarette smoking.28 In addition, Abbott and coworkers, Bonita and colleagues, and Wolf and associates in three separate studies all determined that cigarette smoking was a significant risk factor for stroke,1,3,31 although Himmelmann and colleagues failed to find such an association.14
One of the reasons that modifying smoking behavior is an efficient
preventive intervention is that the adverse health effects of smoking can be abruptly altered by quitting. The ex-smokers risk of coronary heart disease (CHD) 12 months following cessation is approximately that of the person who has never smoked.7 Cessation also slows the development of chronic obstructive pulmonary disease (COPD),11 and Wolf has observed that ex-smokers quickly shed the excess risk of stroke that can be attributed to cigarette smoking.31 Reduction in lung cancer risk, however, is slower, and the ex-smoker will always have a risk for this disease between 1.5 and 2 times that enjoyed by those who have never smoked.7
The 1985 Health Interview Survey26 reported that 30 percent of adults in the United States were current smokers. Although smoking rates were fairly uniform between the ages of 20 and 55, the rate dropped rapidly among the elderly. Those 55 to 64 years of age still maintained a smoking rate of 30.2 percent; of those 65 to 74 years of age the rate was only 21.5 percent, and over age 75 the rate dropped to 8.5 percent.
There are three possible explanations for these findings. First, the birth cohort for those currently over the age of 65 may have had a lower rate of initiating cigarette smoking during adolescence and adulthood (i.e., the ever-smoked rate is lower in these cohorts). Second, it is possible that there are increasing cessation rates among those over age 65. Finally, some of the decrease in smoking rates may be due to the decreased survivorship of smokers. What evidence there is indicates that all three factors may be operative. Secular trends certainly explain some of the lower smoking rates among older women because the habit did not become socially acceptable for women until about 40 years ago. Direct evidence indicates that cessation rates have been observed to increase with age,29 thus confirming the intuitive concept that, because most cessation attempts are unsuccessful, the elderly who have lived longer will therefore have had more opportunities to achieve cessation of smoking. Smoking certainly shortens life expectancy for both sexes, thus selectively eliminating smokers, particularly men, from surviving into old age.
The answer to the question of whether the health effects of cigarette smoking are age specific is complex. There is no evidence for such effects, yet the duration of smoking is an important factor
and pack-years of cigarette smoking an important variable for lung and other cancers. Therefore, one may assume that duration and rate of cigarette smoking would be more important than age, although the two obviously would be related because the elderly would have had an opportunity to smoke for more years than the members of younger birth cohorts. Evidence has shown, however, that the current rate of cigarette smoking is the most important smoking variable related to cardiovascular disease, including coronary heart disease, stroke, and peripheral arterial disease (i.e., intermittent claudication).10 In addition, Branch reported that cigarette smoking was associated with subsequent physical disability among a cohort of elderly men.4
The evidence also indicates that cigarette smoking continues to shorten life expectancy beyond the age of 50 and that it continues to predict lung and other cancers.8 Jajich and coworkers determined that, among a sample of 2,674 persons aged 65 to 74 years, the coronary heart disease death rate of current cigarette smokers was 52 percent higher than the rates for nonsmokers, ex-smokers, and those who smoked pipes and cigars.15 Moreover, Branch and Jette determined that never smoking cigarettes was the only personal health practice that achieved a statistically significant multivariate relationship with lower mortality.5
Khaw and colleagues studied the predictors of stroke-associated mortality in the Rancho Bernardo study and determined that cigarette smoking was a stronger predictor of stroke mortality than blood pressure.16 It was also a significant risk factor for stroke with relative risks ranging close to 2.0 for heavy (i.e., 40 cigarettes or more per day) smokers. The evidence regarding CHD and peripheral arterial disease among seniors, however, is much less convincing. Whereas cigarette smoking is a powerful risk factor for these diseases for individuals under the age of 65, particularly men, the effect weakens markedly for both sexes over that age. Some studies suggest that cigarette smoking predicts both mortality and recurrence in patients who have developed coronary heart disease,29 although data from the Framingham study regarding smokers and nonsmokers following acute myocardial infarction have not confirmed these findings. Recent data from the Coronary Artery Surgery Study (CASS) on the effects of smoking cessation among 1,893 men and women over the age of 55 with documented CHD demonstrated that the six-year mortality rate was greater for those who continued to smoke than for those who had quit the year before entering the study and who had continued to abstain. Furthermore, the beneficial effect did not decrease with increasing age.13
Earlier data from the CASS had shown that a history of cigarette smoking was one of five variables that predicted perioperative mortality following coronary artery bypass grafting.9 The Duke Longitudinal Study, which followed volunteers 60 to 94 years of age, found associations between exercise, maintaining moderate weight, and abstention from cigarette smoking and both lower mortality and illness rates among its sample.22 In addition, Rundgren and Mellstrom suggest that cigarette smoking may be a cause of osteoporosis. Their studies revealed that, of 409 men and 559 women between the ages of 70 and 79, the smokers had a bone mineral content that was 10 to 30 percent lower than that of nonsmokers.25
In summary, the weight of the evidence indicates that cigarette smoking continues to be a risk factor for untimely death from all causes in persons over the age of 50. As people age, however, smoking becomes less predictive of certain forms of cardiovascular disease.
EVIDENCE THAT SMOKING CESSATION IS BENEFICIAL
For both practical and ethical reasons, there have been no double-blind, randomized trials of the effects of cessation of cigarette smoking. Therefore, it has been necessary to derive data regarding these effects from multiple risk factor intervention trials that have included cigarette smoking intervention or from observations of large cohorts over time (comparing quitters with never-smokers and smokers).6 These data are limited in other respects as well: intervention trials are often restricted to men (e.g., the multiple risk factor intervention trials),18 and analyses have rarely focused selectively on the elderly.
The available data indicate that cigarette smoking cessation increases life expectancy at all ages and that the increase for older individuals, although less in the absolute number of years than for younger subjects, is proportionally as great.6 The benefits are most prompt for coronary and other manifestations of cardiovascular disease in which the full benefits may be realized within the first 12 months after cessation. Cancer risk reduction, on the other hand, takes place more slowly; consequently, the risk of ex-smokers remains between 1.5 and 2 times that of nonsmokers even after 10 years or more of abstention. Other benefits include an improved sense of smell and improved pulmonary function. However, quitters on average gain 5 pounds in weight during the subsequent 12 months, and the weight gain is proportional to the smoking rate prior to cessation. Although some of this increase may be due to increased caloric intake, most of the gain can be ascribed to the elimination of the
metabolic effects of nicotine, which can account for as many as 500 kilocalories per day.2 There is no evidence that these effects are any different for seniors than they are for younger individuals.
SMOKING CESSATION TECHNIQUES
Most individuals who have stopped smoking do so on their own with only informal encouragement from family, friends, and health professionals. Yet the rate of smoking cessation has slowed among certain age-sex groups, and smoking rates are actually increasing among poor women.30 These data suggest that formal smoking cessation techniques may gain increasing importance during the next decade if a smoke-free society in the United States is to be achieved by the year 2000.
Physicians play an important role in cigarette smoking cessation. More than two-thirds of U.S. adults have a professional encounter with a physician each year. For the elderly, this figure may exceed 90 percent. Many of these visits are for symptoms of smoking-related diseases, thus increasing the likelihood that the patient will be motivated to quit.25 Some studies, based on patient interviews, have reported that fewer than half of patients who smoke can recall their physician counseling them to stop.21 These studies disagree with other data from physicians that indicate that as many as 85 percent counsel their patients on some health issue at the time of office visits. Far fewer physicians, however, feel competent to counsel patients regarding smoking cessation, and in one survey only 3 percent31 were confident of their effectiveness. Some investigators have attempted to improve physicians' counseling skills. For example, Ockene and coworkers used a three-hour training program to teach family practice and internal medicine residents patient-centered counseling techniques. After completion of the program the residents demonstrated a significant increase in knowledge and a perception of themselves as having more influence on their patients who smoked.19
Formal smoking cessation techniques include group counseling with peer support, aversion techniques such as rapid smoking, and hypnosis. Nicotine-containing chewing gum has also been evaluated as an adjuvant to help patients stop smoking.16,23 Its efficacy largely depends on how it is used: it has been shown to be effective if combined with behavioral programs, particularly for heavy smokers who are highly dependent on nicotine, but if prescribed alone, it is of little or no benefit. Unfortunately, few studies have attempted to evaluate the relative effectiveness of these programs among older individuals as compared with younger smokers.
The health risks of passive smoking of side-stream smoke are far less than the risks incurred by smoking of the mainstream. Nevertheless, relative risks of up to 3.3 for cancer of the lung have been reported for nonsmoking wives of smoking husbands.22 The size of the risk indicates that passive smoking is a problem that should be addressed.
Those Over the Age of 50
Those older individuals who smoke cigarettes should be made aware of both the deleterious health effects of cigarette smoking and the many health and other benefits of quitting and should discuss the various cessation methods with their primary care physician.
Elders who are ex-smokers should advise their smoking peers of the health and other benefits they will enjoy after quitting.
The surgeon general's goal of a smoke-free environment by the year 2000 should be actively supported.
Physicians and other health professionals should set a good example by not smoking cigarettes. Those who are ex-smokers should draw on their own personal experiences during smoking withdrawal in counseling their smoking patients.
A smoking history on all patients should always be taken.
Health care professionals should assess their smoking patients' motivation for quitting and improve their skill in counseling such patients in the office-practice setting.
Physicians and other health professionals should familiarize themselves with the formal smoking cessation programs available in patients' communities.
Nicotine-containing gum should be prescribed appropriately and effectively.
Public Health and Environmental Policymakers
The feasibility of applying the same controls for the sale of cigarettes as those now established for the sale of alcoholic beverages should be considered.
Policymakers should continue to develop and enforce regulations prohibiting cigarette smoking on common carriers and in other public places.
The establishment of a tax on cigarettes should be studied, that is, a tax sufficient to cover both the direct and indirect costs of cigarette smoking borne by local, state, and federal governments.
State and federal legislation should be proposed to permit the smoking-risk rating of both life and health insurance.
Federal subsidies to tobacco growers should be eliminated.
All school health education programs should be required to include curriculum on the risk of smoking.
Cigarette advertising should be prohibited.
Research should continue to focus on effective means of smoking cessation. Research should also focus on eliminating the initiation of smoking.
Efforts should continue to pressure policymakers and legislatures to promote antismoking health measures.
Formal smoking prevention and smoking cessation programs should be developed and promoted.
Print, audio, and visual aids to prevent cigarette smoking initiation and promote cigarette smoking cessation should be made available to those who need them. In addition, industry should continue to develop products that can assist health professional and voluntary health agencies to prevent the initiation of cigarette smoking by those who have never smoked and encourage its cessation among those who do.
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3. Bonita, R., Scragg, R., Stewart, A., et al. Cigarette smoking and the risk of premature stroke in men and women. British Medical Journal of Clinical Research 1986; 295:6-9.
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