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The economic costs of smoking and benefits of quitting for individual smokers
PREVENTIVE
MEDICINE
The Economic
13, 377-389 (1984)
Costs of Smoking and Benefits Individual Smokers’
GERRY OSTER,*T* GRAHAM
A. COLDITZ,~
AND NANCY
of Quitting
for
L. KELLY*
*Policy Analysis Inc., 1577 Beacon Street, Brookline, Massachusetts 02146, and tDepartment Medicine, Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts 02115
of
The results of a study that estimated the expected lifetime economic consequences of cigarette smoking for individual smokers are reported herein. The estimates were obtained by combining age- and sex-specific estimates of the incidence-based costs of three smokingrelated diseases (lung cancer, coronary heart disease, and emphysema) with estimates of smokers’ increased likelihood of developing these illnesses in each remaining year of lie relative to nonsmokers. Estimates of the economic consequences of quitting based on these disease cost estimates and on estimates of exsmokers’ probability of future disease relative to continuing smokers are also reported. Both the estimates of the economic costs of smoking and the benefits of quitting were calculated separately for men and women between the ages of 35 and 79 who were light, moderate, or heavy cigarette smokers. While the economic costs of smoking varied considerably by sex, age, and amount smoked, they were significant for all groups of smokers. Costs for a 40-year-old man, for example, ranged from $20,000 for a smoker of less than one pack of cigarettes per day to over $56,000for a smoker of more than two packs of cigarettes per day. The economic benefits of quitting also were found to be sizable for all groups of smokers. o 19~4 Academic POW. I~C.
INTRODUCTION
Although the health consequences of cigarette smoking have been well documented (19-22), relatively little is known about the economic consequences of these adverse effects on smokers’ health. Existing studies of the economic impact of smoking have employed prevalence-based approaches, typically estimating the cost of current smoking-related morbidity and premature mortality (1, 13, 14). No study, however, has utilized an incidence-based approach, which focuses on the present value of future costs of morbidity and mortality. Consequently, little is known about the magnitude of future economic costs for smokers who are currently disease-free or about the potential economic benefits of quitting. In this article, we report estimates of both the expected economic costs of smoking and the benefits of quitting for current smokers. Incidence-based cost-of-illness procedures were first used to estimate the present value of the lifetime costs of illnesses that smokers might develop as a consequence of cigarette smoking. These costs included treatment expenses (direct costs) as well as the value of illness-related work loss due to premature death and disability (indirect costs) (11). Estimation of the expected costs of smoking ’ Funds for this research were provided by a research grant from Merrell Dow Pharmaceuticals Inc. 2 To whom reprint requests should be addressed. 377
0091-7435/84$3.00 Copyright 0 1984 by Academic Press, Inc. All rights of reproduction in any form reserved.
378
OSTER, COLDITZ,
AND KELLY
then was based upon an evaluation of the increased probability (or marginal risk) that smokers (as compared with nonsmokers) will develop these diseases in each future year of life. The economic benefits of quitting were estimated in a similar fashion, the focus in this instance being on quitters’ reduced likelihood of disease relative to continuing smokers. Therefore, in contrast to traditional cost-of-illness studies that focus on the costs of disease among the ill (1 l), our approach combined information on the costs of smoking-related illnesses with estimates of the health risks of smoking in order to generate estimates of the likely (i.e., expected) future costs of smoking and of the benefits of quitting for individuals currently disease-free. Due to limitations in data, we confined our study to three major disease conditions: lung cancer, coronary heart disease [CHD; comprising three distinct diagnostic categories: sudden death (SD), myocardial infarction (MI), and coronary insufficiency (CI)], and emphysema. The costs of smoking reported here reflect the average economic losses that current smokers are likely to generate over a lifetime because of their increased risks of developing these three diseases. Similarly, the reported benefits of quitting reflect expected reductions in economic losses as a result of lifelong reductions in the risks of developing lung cancer, CHD, and emphysema. All estimates are expressed in 1980 dollars and take into account all direct and indirect costs that smokers are likely to generate, whether they are the ones who will ultimately assume these costs or not. Our estimates of the costs of smoking and benefits of quitting are probably conservative. While lung cancer, CHD, and emphysema are unquestionably the major disease conditions that have been linked to smoking, smoking has been implicated in the etiology of other chronic and neoplastic disease conditions that are not considered in this study (20). Also, our estimates do not take into account economic costs other than those directly related to disease (e.g., the costs of residential and commercial fires), noneconomic costs, or the costs of smokingrelated diseases among nonsmokers (i.e., the costs of passive smoking). Finally, our estimates of the costs of smoking and the benefits of quitting do not include the cost of cigarettes. ANALYTICAL
FRAMEWORK
Our analytical framework likened smoking to a game of chance.3 In effect, every smoker was viewed as engaging in a lifelong series of gambles with his or her health, each occurring in a successive future year of life. The unlucky “winners” in any year’s gamble develop one of a variety of smoking-related diseases and generate its attendant economic costs, comprising treatment expenses and lost earnings. As with any game of chance, we may characterize each gamble by the average outcome experienced by its participants, or the expected value (EV). Simply put, the EV is equal to the probability of winning (or losing) multiplied by the amount that one can win (or lose). Thus, for example, the EV of a costless 3 A complete presentation of the methods employed in this study is contained in Chapter 2, “Estimating the Economic Costs of Smoking and Benefits of Quitting,” in Oster et al. (17).
COSTS OF SMOKING,
BENEFITS
OF QUITTING
379
lottery in which there is a l-in-l,000 (0.001) chance of winning $1,000 (and a 999in-l,000 chance of winning nothing) is $1 (or, $1,000 x 0.001). In the case of smoking, of course, the outcome at risk is a potential loss rather than a gain. At any point in time, each future year’s gamble may be represented by the additional likelihood that a smoker will develop a smoking-related disease during that year (given that he or she both lives and remains disease-free until that year). Corresponding to each of these future gambles, there is an associated economic cost (the sum of the direct and indirect costs of illness) that represents the amount that would be lost if an illness were to develop in that year of life. The smoking “gamble” can thus be characterized by a series of EVs, each representing an expected economic loss in a successive year of life. The costs of smoking for a current smoker are equal to the sum of these expected annual losses, each discounted to reflect its appropriate present value.4 Calculation of the costs of smoking therefore depends upon estimation of the lifetime costs of smokingrelated diseases at every possible age of onset as well as smokers’ increased likelihood of developing these diseases at each age. Just as there are expected costs of smoking resulting from the higher probability of serious illness, so there are expected economic benefits associated with reductions in the risk of disease. By definition, these benefits are equal to the losses (i.e., costs of illness) that are likely to be avoided by individuals who quit smoking. Hence, the benefits of smoking cessation may be represented by a series of expected annual,cost savings. As with the calculation of smoking costs, summation of these expected annual cost savings, each appropriately discounted to reflect the year to which it corresponds, yields an estimate of the economic benefits of quitting. If quitting resulted in an immediate elimination of all future increased risk of disease, the estimation of associated economic benefits would be a trivial undertaking. If all expected future costs of smoking could be avoided, then the dollar value of benefits simply would be equal to the amount of these costs. The elimination of marginal disease risks is not instantaneous, however; while former smokers experience significant reductions in their risks of smoking-related illnesses soon after quitting, these risks nonetheless remain higher than those of nonsmokers for a number of years. Hence, the economic benefits of quitting are equal to the difference between current smokers’ and former smokers’ expected additional costs of illness (relative to nonsmokers). Quitters’ expected cost savings in any given future year will be less than smokers’ anticipated losses in that year if the quitters experience risks of disease in excess of those experienced by nonsmokers. The benefits of quitting are thus a function of the rate at which smokers’ likelihood of disease declines in the period after quitting, and the calculation of these benefits necessitates the estimation of these reductions in annual disease risk. 4 Costs that do not accrue in the same year should not be directly summed, since they are expressed in different units of value, i.e., different years’ dollars. Discounting is a technique that expresses these costs in terms of their value in a common reference year.
380
OSTER, COLDITZ,
AND KELLY
SMOKERS’ MARGINAL RISKS OF LUNG CANCER, CORONARY HEART DISEASE, AND EMPHYSEMA Due to limitations in available data, it was assumed that smokers’ marginal risk of disease depended only upon age, sex, and amount smoked, but not on the length of time they had smoked. Estimated marginal risks of lung cancer, CHD (SD, MI, and CI), and emphysema for light, moderate, and heavy smokers are presented in Table 1, expressed in terms of the number of additional cases annually relative to nonsmokers per 100,000 population (or marginal rates of incidence), for men and women in 5-year age increments. Lung Cancer Sex- and age-specific lung cancer incidence rates for nonsmokers were estimated using data reported by Garlinkel (8). Lung cancer incidence rates for current smokers were obtained by first multiplying data on total sex- and age-specific U.S. lung cancer incidence by the estimated proportions of reported lung cancers (82.8% for men and 43.1% for women) attributable to smoking (9, 15). These totals were then divided by the number of current and former smokers in each age-sex group; the resultant rates were assumed to be average incidence rates for all current smokers. Separate sets of incidence rates for light, moderate, and heavy smokers were then generated from these average rates using data on relative risk that were contained in the 1982 Surgeon General’s Report (22). Coronary Heart Disease Sudden death, myocardial infarction, and coronary insufficiency incidence rates for nonsmokers and for light, moderate, and heavy smokers were taken directly from the Framingham Heart Study (FHS) (6, 7).5 For FHS participants over the age of 65, incidence rates were actually slightly lower for smokers than nonsmokers, but this finding was not statistically significant. Therefore, it was assumed that smoking had no effect on CHD risk past the age of 65, and zero marginal incidence rates are indicated for these smokers in Table 1. Emphysema Emphysema is almost exclusively a smokers’ disease; the lung obstruction characteristic of emphysema is almost never observed among nonsmokers (4, 5). Therefore, a zero rate of incidence was assumed for nonsmokers. Emphysema incidence rates for smokers were calculated from estimated prevalence rates obtained by dividing U.S. sex- and age-specific prevalence by the number of current and former smokers in each age-sex group (16). Incidence rates for smokers were then generated from these prevalence rates, assuming a mean survival time of 5 years past diagnosis (2, 12). The resultant estimates were assumed to be mean incidence rates for all current smokers. Separate sets of incidence rates for light, moderate, and heavy smokers were then generated using these average rates and data on relative risk reported by Ferris et al. (3). 5 For women between the ages of 35 and 44, these rates are reported for MI only.
Men 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 Women 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79
-
7 21 39 60 88 111 116 109 81
9 9 0 0 0 0 0
9 9 33 33 44 44 0 0 0
SD
13 48 125 226 273 575 784 948 989
LC
4 4 20 20 27 27 0 0 0
27 27 104 104 155 155 0 0 0
MI
0 0 33 33 0 0 0
-
9 9 17 17 12 12 0 0 0
CI
63 95 164 214 252 296 914 1,084 1,216
122 252 394 537 673 809 1,278 1,476 1,673
Em
Light smokers (less than 1 pack per day)
15 44 84 127 189 236 255 240 205
25 85 217 389 645 990 1,355 1,634 1,727
LC
Moderate
30 30 46 46 59 59 0 0 0
30 30 0 0 0 0 0
59 59 258 258 343 343 0 0 0
MI
28 28 90 90 96 96 0 0 0
SD
0 0 75 75 0 0 0
-
28 28 36 36 26 26 0 0 0
CI
100 150 260 340 400 470 1,450 1,720 1,930
180 370 580 790 990 1,190 1,880 2,170 2,460
Em
smokers (1 to 2 packs per day)
-
24 68 130 196 294 366 399 377 334
33 109 277 4% 825 1,264 1,732 2,088 2,215
LC
80 80 0 0 0 0 0
67 67 185 185 158 158 0 0 0
SD
194 194 80 80 126 126 0 0 0
97 97 486 486 571 571 0 0 0
MI
0 0 129 129 0 0 0
-
67 67 60 60 43 43 0 0 0
CI
230 345 598 782 920 1,081 3,335 3,956 4,439
324 666 1,044 1,422 1,782 2,142 3,384 3,906 4,428
Em
Heavy smokers (more than 2 packs per day)
TABLE 1 ADDITIONAL ANNUAL CASES OF LUNG CANCER (LC), SUDDEN DEATH (SD), MYOCARDIAL INFARCTION (MI), CORONARY INSUFFICIENCY (CI), AND EMPHYSEMA (EM) FOR LIGHT, MODERATE, AND HEAVY SMOKERS (PER 100,000 PERSONS)
382
OSTER, COLDITZ,
THE ECONOMIC
AND KELLY
COSTS OF SMOKING
The EV of the loss a smoker may experience in any future year of life is roughly equal to his or her marginal risk of disease in that year (presented in Table 1) multiplied by the corresponding costs of illness that may be incurred. (The lifetime costs of lung cancer, CHD, and emphysema were estimated by the authors for men and women between the ages of 35 and 79 (17), but are not reported here due to space limitations.) The costs of smoking are equal to the discounted sum of this series of expected losses. Estimates of the costs of smoking associated with increased lifelong risks of lung cancer, CHD, and emphysema for men and women between the ages of 35 and 79 are reported in Table 2. These costs were estimated in 5-year age groups for light, moderate, and heavy smokers, and were tallied in 1980 dollars using a 3% annual real (i.e., net of inflation) rate of discount and assuming a 1% future real rate of growth in labor productivity (which was used in the valuation of forgone earnings). In addition, we assumed that a smoker’s current level of cigarette consumption would remain constant throughout life; cost estimates therefore reflect the level of losses likely to result if no change occurs in smoking habits. While none of the three disease conditions may uniformly be described as the single, most costly expected consequence of smoking, the costs of smoking due to increased risk of emphysema are greatest across nearly all of the categories investigated. For example, for men ages 40-44 who are moderate smokers, the costs of smoking associated with lung cancer, CHD, and emphysema are, respectively, about $7,100, $6,500, and $19,600; the corresponding costs for women are approximately $2,000, $500, and $6,500a6The comparatively high costs of smoking associated with emphysema result from smokers’ higher marginal risks of this disease in comparison with lung cancer and CHD (see Table I), since the lifetime costs of emphysema are actually slightly lower than those of the other two disease conditions (17). Regardless of disease, the expected costs of smoking are consistently higher, controlling for age and sex, as the quantity of cigarettes smoked increases. For men ages 40-44, for example, the expected costs for heavy smokers are more than twice those for light smokers for lung cancer and emphysema ($9,055 vs $4,175, and $35,333 vs $13,348, respectively). For CHD, heavy smokers’ costs are almost five times higher ($12,282 vs $2,664). Also, almost without exception, the costs of smoking are highest for the youngest age group, controlling for sex and quantity smoked, and decline gradually with age. 6 Lower cost-of-smoking estimates for women are the products of two factors. First, existing epidemiological data sources suggest that women experience generally lower marginal disease risks than men at any given age and level of smoking (see Table 1). This could be the result of a number of factors, ranging from sex differences in smoking behavior (for example, depth of inhalation or number of “drags” per cigarette) to differences between men and women in disease etiology. Second, the costs of smoking for women are also lower because of women’s lower earning levels, which result in lower potential earnings losses. These differences in costs of smoking typically vanish by the age of 65.
214b 214b 342 245 164 55 0 0 0
939 985 968 891 788 685 541 340 210
v334
2,186 1,352 705 193 0 0 0
$2,874
$3,940 4,175 4,042 3,500 2,732 2,025 1,551 1,158 812
4,261 4,075 3,680 3,106 2,606 2,298 1,921 1,296 836
$14,753 13,348 10,530 7,188 4,313 2,607 1,850 1,318 946 5,414 5,274 4,990 4,242 3,558 3,038 2,462 1,636 1,046
$21,567 20,187 16,758 12,040 7,550 4,825 3,401 2,476 1,758 1,918 2,011 1,976 1,819 1,608 1,399 1,106 694 429
$6,714 7,114 6,887 5,965 4,656 3,450 2,642 1,974 1,384 6626 5476 859 576 365 122 0 0 0
$7,154 6,543 5,274 3,119 1,546 425 0 0 0
CHD
6,763 6,468 5,841 4,930 4,136 3,647 3,050 2,057 1,328
$21,695 19,629 15,486 10,571 6,343 3,834 2,720 1,939 1,392
Em
9,343 9,026 8,676 7,325 6,109 5,168 4,156 2,751 1,757
$35,563 33,286 27,647 19,655 12,545 7,709 5,362 3,913 2,776
Total
smokers (1 to 2 packs per day)
2,937 3,078 3,026 2,784 2,462 2,142 1,692 1.063 ‘657
2,409b 14476 1,809 1,168 695 233 0 0 0
$13,707 12,282 9,692 5,473 2,551 703 0 0 0
CHD
15,555 14,877 13,434 11,340 9,513 8,389 7,014 4,731 3,054
$39,051 35,333 27,875 19,028 11,417 6,901 4,896 3,490 2,505
Em
20,901 19,402 18,269 15,292 12,670 10,764 8,706 5,794 3,711
$61,304 56,670 46,334 32,093 19,894 11,995 8,259 6,003 4,266
Total
smokers (more than 2 packs per day)
$8,546 9,055 8,767 7,592 5,926 4,391 3,363 2,513 1,761
LC
Heavy
a All costs are in 1980 dollars, discounted at a 3% annual rate, assuming a 1% annual rate of growth in labor productivity. b CHD cost estimates for women between the ages of 35 and 44 are for myocardial infarction only.
Men 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 Women 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79
Total
LC
Em
LC
CHD
Moderate
Light smokers (less than 1 pack per day)
TABLE 2 THE ECONOMIC COSTS OF SMOKING FOR LIGHT, MODERATE, AND HEAVY SMOKERS DUE TO INCREASED RI.YK~ OF LUNG CANCER (LC), CORONARY HEART DISEASE (CHD), AND EMPHYSEMA (EM)”
384
OSTER, COLDITZ,
AND KELLY
While summation of costs across diseases will not produce precise estimates of the total costs of smoking, it can provide some indication of their likely magnitude.7 As Table 2 indicates, these total costs are sizable, particularly for heavy smokers under the age of 50. For example, male heavy smokers between the ages of 40 and 44 will generate, on average, over $56,000 in additional costs of illness during their lifetimes, while for women, these costs will be over $19,000. Although costs decline with both age and quantity of cigarettes smoked, they are significant for all smokers. QUITTING AND REDUCTIONS IN MARGINAL RISKS OF LUNG CANCER, CORONARY HEART DISEASE, AND EMPHYSEMA The economic benefits of smoking cessation are a byproduct of reductions in future likelihood of disease. Calculation of these benefits requires that these disease risk reductions be estimated. We assumed that they depended both upon the amount that one had previously smoked and the length of time since quitting. Lung Cancer
The impact of smoking cessation on future lung cancer risk was estimated on the basis of findings reported by Hammond for annual excess lung cancer mortality among male exsmokers ages 50-69 (IO). Former light smokers were found to return to nonsmokers’ risk levels approximately 5 years after quitting. Former heavy smokers, however, did not return to nonsmokers’ levels of lung cancer mortality until more than 10 years after they stopped smoking. We assumed that these results would apply to smokers of all age-sex groups, and that the effect of quitting on lung cancer incidence would be identical to its effect on lung cancer mortality. On the basis of Hammond’s findings, logit functions were used to estimate the proportion of marginal lung cancer risk that was likely to be experienced by former light, moderate, and heavy smokers in each year after they stopped smoking. The marginal risk of lung cancer in each year after quitting for an exsmoker of any given age, sex, and prior amount smoked was then calculated by multiplying a corresponding smoker’s estimated marginal risk (Table 1) by the proportion of this risk that a quitter was likely to experience. Coronary Heart Disease
The impact of smoking cessation on future CHD (SD, MI, and CI) risk also was estimated on the basis of findings reported by Hammond for male exsmokers ’ On the one hand, since other chronic and neoplastic diseases have been linked to cigarette smoking, the sum of smoking-related costs associated with lung cancer, CHD, and emphysema tends to understate significantly the actual total costs of smoking. Counterbalancing this, however, is the fact that adding the costs related to these three diseases together would tend to overstate actual total expected costs if a smoker can develop more than one of these diseases. While actual treatment expenses may or may not be less than the sum of treatment costs for each disease when two diseases are present, earnings losses definitely will be less than the sum of estimated indirect costs for each, since an individual cannot forgo the same earnings stream twice.
COSTS OF SMOKING,
BENEFITS
OF QUITTING
385
between the ages of 50 and 69 (10). Former light smokers experienced a marked decline in excess CHD mortality within one year of quitting, and the decline to nonsmokers’ risk levels was complete by the tenth year after cessation. Former heavy smokers, though, did not return to nonsmokers’ levels of CHD mortality until about 15 years after they stopped smoking. As with lung cancer, we assumed that Hammond’s reported findings would apply to smokers in all age-sex groups, and that the effect of quitting on SD, MI, and CI incidence would be identical to its effect on CHD mortality. In a manner similar to that used for lung cancer, the proportion of CHD risk that exsmokers were likely to experience in each year after quitting was estimated. These were then multiplied by the marginal risks of continuing smokers (Table 1) to yield estimated marginal SD, MI, and CI risks for former light, moderate, and heavy smokers. Emphysema
In nonsmokers, respiratory function typically declines at the rate of about 30 ml per year after age 30 (5). For smokers, the rate of decline can be two to three times as great, or about 60-100 ml per year. Once smokers quit, though, their rate of decline in respiratory function almost always reverts to that of nonsmokers (5). Despite the fact that the rapid declines in pulmonary function characteristic of emphysema stop once a smoker quits, prior loss of lung function is permanent. Because of this, former smokers may still develop emphysema several years after quitting. Normal (i.e., nonsmokers’) additional losses of pulmonary function, together with earlier smoking-related losses, may still be sufficient to result in a diagnosis of emphysema later in life. To estimate the effect of quitting on future emphysema risk, we first assumed that individuals quit voluntarily -not because of experiencing symptoms of chronic obstructive lung disease. Second, we assumed that disease incidence among exsmokers in the year immediately following cessation would be equal to that experienced by continuing smokers. Finally, in the second and all subsequent years after quitting, we assumed that disease risks would be reduced by an amount proportionately equal to the relative improvement in the rate of pulmonary function decline. Thus, for example, assuming an initial 80 ml/year decline in respiratory function, we estimated that a moderate smoker who quit would experience a marginal risk of emphysema in the second and all later years of life following cessation equal to 38% of the marginal risk experienced by a continuing smoker (30 ml/year divided by 80 ml/year). An exsmoker’s marginal risk of emphysema in any given year following cessation was then estimated by multiplying a smoker’s marginal risk (Table 1) by the proportion of this risk that quitters were likely to experience in that year. THE ECONOMIC
BENEFITS
OF QUITTING
Estimates of the benefits of quitting associated with lifelong reductions in the risks of lung cancer, CHD, and emphysema are reported in Table 3 for men and
818 776 695 598 490 347 212 124 74
$3,421 3,119 2,546 1,892 1,343 941 629 388 218
186b 164b 222 144 60 9 0 0 0
$2,331 1,909 1,240 657 226 29 0 0 0
CHD
1,999 1,889 1,663 1,383 1,155 1,023 791 524 330
$6,882 6,032 4,588 3,010 1,741 1,060 739 522 364
Em
3,003 2,829 2,580 2,125 1,705 1,379 1,003 648 404
$12,634 11,060 8,374 5,559 3,310 2,030 1,368 910 582
Total
1,489 1,362 1,185 982 741 488 292 168 96
4,304 3,325 2,391 1,657 1,1’08 699 407 221
$5,046
LC
4436 332b 446 254 99 14 0 0 0
$5,195 3,930 2,364 1,127 360 47 0 0 0
CHD
3,967 3,751 3,307 2,753 2,302 2,043 1,580 1,046 658
$12,654 11,095 8,445 5,546 3,217 1,965 1,372 968 673
Em
5,899 5,445 4,938 3,989 3,142 2,545 1,872 1,214 754
$22,895 19,329 14,134 9,064 5,234 3,120 2,071 1,375 894
Total
smokers (1 to 2 packs per day)
2,280 2,085 1,815 1,503 1,134 748 447 258 147
9556 5796 729 358 123 20 0 0 0
$8,545 5,815 3,189 1,350 387 56 0 0 0
CHD
10,359 9,800 8,645 7,205 6,034 5,357 4,145 2,743 1,724
$25,861 22,679 17,269 11,351 6,596 4,040 2,823 1,990 1,381
Em
13,594 12,464 11,189 9,066 7,291 6,125 4,592 3,001 1,871
$40,829 33,973 24,690 15,745 9,093 5,507 3,713 2,509 1,662
Total
smokers (more than 2 packs per day)
$6,423 5,479 4,232 3,044 2,110 1,411 890 519 281
LC
Heavy
0 All benefits are in 1980 dollars, discounted at a 3% annual rate, assuming a 1% annual rate of growth in labor productivity. b CHD benefit estimates for women between the ages of 35 and 44 are for myocardial infarction only.
Men 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 Women 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79
LC
Moderate
TABLE 3 FOR LIGHT, MODERATE, AND HEAVY SMOKERS DUE TO REDUCTIONS IN THE RISK OF LUNG CANCER (LC), CORONARY HEART DISEASE (CHD), AND EMPHYSEMA (EM)
Light smokers (less than 1 pack per day)
THE ECONOMIC BENEFITS OF QUI~ING
COSTS OF SMOKING,
BENEFITS OF QUITTING
387
women between the ages of 35 and 79. Our benefit estimates for light, moderate, and heavy smokers are reported in j-year age groups, and were tallied in 1980 dollars using the same real rates of discount and productivity growth that were used to calculate the costs of smoking. Benefits were measured against the costs that were likely to be generated by individuals who continued to smoke an identical amount throughout their lifetimes. In addition, we assumed that once a smoker quit, it would be for life. Our estimates of the benefits of quitting are not surprising in light of our findings regarding the costs of smoking. The greatest benefits were found to be associated with reduced risks of developing emphysema, although they are sizable irrespective of disease condition. For example, for men ages 40-44 who are moderate smokers, the benefits of quitting associated with reduced risks of lung cancer, CHD, and emphysema are, respectively, about $4,300, $3,900, and $11,100; the corresponding figures for women are approximately $1,500, $300, and $3,800. As expected, these benefits are consistently higher for those who were formerly heavy smokers, and are greatest for persons in the youngest age groups. Summation of benefits across the three diseases suggests that the total benefits of quitting are sizable.8 For male heavy smokers under the age of 45, the present value of total lifetime dollar benefits is about $34,000, and for women, the corresponding total is over $12,000. Even for the very oldest age groups (i.e., age 70 and over), the total benefits of quitting are by no means inconsequential. For men, they range from about $600 to slightly over $2,500; for women, the range is from $400 to about $3,000. DISCUSSION
This study has found that the expected costs of cigarette smoking for individual smokers are substantial. While these costs vary with sex, age, and the amount smoked, there was no group of smokers that was not expected to generate sizable losses. Furthermore, the results of this study have shown that, at any age, it literally pays to stop smoking, since the benefits of quitting are also sizable. The relative effectiveness of smoking cessation may be conveniently assessed by computing ratios of the overall benefits of quitting to the total costs of smoking.9 What each reveals is the expected proportion of smoking-related losses that a given smoker can avoid by quitting. In a sense, these ratios indicate the extent of “cost recovery” possible; the higher this ratio, the greater the relative benefits of quitting. 8 Considerations similar to those noted in footnote 7 apply to the addition of benefits-of-quitting estimates across diseases. 9 While these cost recovery ratios are equal to the ratio of the benefits of quitting to the costs of smoking, it is not a benefit-cost ratio in the traditional sense. A benefit-cost ratio compares the benefits and costs of one specific course of action, while the ratio of the benefits of quitting to the costs of smoking compares the results of two alternative courses of action (i.e., quitting vs continuing to smoke). Related to this difference is the fact that our cost recovery ratios will always be less than 1 since an exsmoker’s risk of developing a smoking-related disease does not return to that of a nonsmoker for a number of years after smoking cessation. Consequently, the benefits of quitting for an exsmoker can never be as great, in absolute terms, as the costs of continuing to smoke.
OSTER, COLDITZ,
388
AND KELLY
TABLE 4 TOTAL COST RECOVERY RATIOS FOR LIGHT, MODERATE, AND HEAVY SMOKERS
Men 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 Women 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79
Light smokers
Moderate smokers
Heavy smokers
0.586 0.548 0.500 0.462 0.438 0.421 0.402 0.368 0.331
0.644 0.581 0.511 0.461 0.417 0.405 0.386 0.351 0.329
0.666 0.608 0.511 0.491 0.457 0.459 0.450 0.418 0.322
0.555 0.536 0.517 0.501 0.479 0.454 0.407 0.396 0.386
0.631 0.603 0.569 0.545 0.514 0.493 0.450 0.441 0.429
0.650 0.642 0.613 0.593 0.576 0.569 0.528 0.518 0.504
Estimated cost recovery ratios for men and women are presented in Table 4. Although these ratios are highest for younger smokers, it is apparent that it is literally never too late to stop smoking. While quitters below the age of 45 are likely to avoid between 54 and 67% of expected lifetime losses due to smoking, even those over the age of 70 are likely to avoid between 32 and 52% of these expected losses. Our findings have many potential uses. For individual smokers, they may provide yet another powerful argument against smoking. Similarly, physicians may find them useful in encouraging their patients to quit smoking. Corporate decision makers also may find our estimates useful in their attempts to evaluate the cost effectiveness of employer-sponsored smoking cessation programs. Finally, our study undoubtedly will prove useful to policymakers in government as they increasingly turn their attention to the economic burden of the health consequences of cigarette smoking and the question of who should ultimately pay these staggering costs. REFERENCES 1. Cady, B. Cost of smoking. New Engl. J. Med. 308, 1105 (1983). 2. Diener, C. F., and Burrows, B. Further observations on the course and prognosis of chronic obstructive lung disease. Amer. Rev. Resp. Dis. 11, 719-724 (1975). 3. Ferris, B. G., Chen, S. P., and Murphy, L. H. Chronic nonspecific respiratory disease in Berlin, New Hampshire: A further follow-up study. Amer. Rev. Resp. Dis. 113, 475-485 (1976). 4. Fletcher, D., and Peto, R. The natural history of chronic airtlow obstruction. Brit. Med. J. 1, 1645-1648 (1977).
COSTS OF SMOKING,
BENEFITS
OF QUITTING
389
5. Fletcher, D., Peto, R., Tinker, C., and Speizer, F. E. “The Natural History of Chronic Bronchitis and Emphysema, An Eight-Year Study of Early Chronic Obstructive Lung Disease in Working Men in London.” Oxford Univ. Press, Oxford, 1976. 6. “The Framingham Study. An Epidemiological Investigation of Cardiovascular Disease, Section 26: Some Characteristics Related to the Incidence of Cardiovascular Disease and Death; Framingham Study, 16-Year Follow-up.” Department of Health, Education, and Welfare, Washington, D.C., 1970. 7. “The Framingham Study. An Epidemiological Investigation of Cardiovascular Disease, Section 30: Some Characteristics Related to the Incidence of Cardiovascular Disease and Death: Framingham Study, l&Year Follow-up.” Department of Health, Education, and Welfare, Washington, D.C., 1974. 8. Garfinkel, L. Cancer mortality in non-smokers: Prospective study of the American Cancer Society. J. Natl. Cancer Inst. 65, 1169-1173 (1980). 9. Hammond, E. C., and Seidman, H. Smoking and cancer in the United States. Pro. Med. 9, 169173 (1980). 10. Hammond, E. C. Smoking in relation to the death rates of one million men and women, in “Epidemiologic Approaches to the Study of Cancer and Other Chronic Diseases” (W. Haenszel, Ed.), National Cancer Institute Monograph No. 19. U.S. Govt. Printing Office, Washington, D.C., 1966. 11. Hartunian, N. S., Smart, C. N., and Thompson, M. S. “The Incidence and Economic Costs of Major Health Impairments.” Heath, Boston, 1981. 12. Kleinbaum, D. G., Kupper, L. L., and Morgenstern, H. “Epidemiologic Research, Principles and Quantitative Methods.” Lifetime Learning Pub., Belmont, Calif., 1982. 13. Lute, B. R., and Schweitzer, S. 0. Smoking and alcohol abuse: A comparison of the economic consequences. New Engl. J. Med. 298, 569-571 (1978). 14. Lute, B. R., and Schweitzer, S. 0. The economics of smoking-induced illness, in “Research on Smoking Behavior” (M. E. Jarvik, J. W. Cullen, E. R. Gritz, et al., Eds.), National Institute on Drug Abuse Research Monograph 17. U.S. Govt. Printing Office, Washington, D.C., 1977. 15. National Cancer Institute. “Surveillance, Epidemiology, and End Results: Incidence and Mortality Data, 1973-1977,” National Cancer Institute Monograph No. 57, NIH Pub. No. 81-2330. National Institutes of Health, Washington, D.C., 1981. 16. National Center for Health Statistics. “Prevalence of Selected Chronic Respiratory Conditions, United States, 1970.” Vital and Health Statistics, Series 10, No. 84, DHEW Pub. No. (HRA) 74-1511, 1974. 17. Oster, G., Colditz, G. A., and Kelly, N. L. “The Economic Costs of Smoking and Benefits of Quitting.” Heath, Boston, 1984. 18. Rice, D. P. “Estimating the Cost of Illness,” Health Economics Series, No. 6, PHS Pub. No. 947-6. U.S. Govt. Printing Office, Washington, D.C., 1966. 19. U.S. Dept. of Health, Education and Welfare. “Report of the Advisory Committee to the Surgeon General of the Public Health Service,” DHEW Pub. No. (PHS) 1103. U.S. Govt. Printing Office, Washington, D.C., 1964. 20. U.S. Dept. of Health, Education and Welfare. “Smoking and Health-A Report of the Surgeon General,” DHEW Pub. No. (PHS) 79-50066. U.S. Govt. Printing Office, Washington, D.C., 1979. 21. U.S. Dept. of Health and Human Services. “The Changing Cigarette-A Report of the Surgeon General,” DHHS Pub. No. (PHS) 81-50156. U.S. Govt. Printing Office, Washington, D.C., 1981. 22. U.S. Department of Health and Human Services. “The Health Consequences of Smoking: Cancer-A Report of the Surgeon General,” DHHS Pub. No. (PHS) 82-50179. U.S. Govt. Printing Office, Washington, D.C., 1982.
MEDICINE
The Economic
13, 377-389 (1984)
Costs of Smoking and Benefits Individual Smokers’
GERRY OSTER,*T* GRAHAM
A. COLDITZ,~
AND NANCY
of Quitting
for
L. KELLY*
*Policy Analysis Inc., 1577 Beacon Street, Brookline, Massachusetts 02146, and tDepartment Medicine, Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts 02115
of
The results of a study that estimated the expected lifetime economic consequences of cigarette smoking for individual smokers are reported herein. The estimates were obtained by combining age- and sex-specific estimates of the incidence-based costs of three smokingrelated diseases (lung cancer, coronary heart disease, and emphysema) with estimates of smokers’ increased likelihood of developing these illnesses in each remaining year of lie relative to nonsmokers. Estimates of the economic consequences of quitting based on these disease cost estimates and on estimates of exsmokers’ probability of future disease relative to continuing smokers are also reported. Both the estimates of the economic costs of smoking and the benefits of quitting were calculated separately for men and women between the ages of 35 and 79 who were light, moderate, or heavy cigarette smokers. While the economic costs of smoking varied considerably by sex, age, and amount smoked, they were significant for all groups of smokers. Costs for a 40-year-old man, for example, ranged from $20,000 for a smoker of less than one pack of cigarettes per day to over $56,000for a smoker of more than two packs of cigarettes per day. The economic benefits of quitting also were found to be sizable for all groups of smokers. o 19~4 Academic POW. I~C.
INTRODUCTION
Although the health consequences of cigarette smoking have been well documented (19-22), relatively little is known about the economic consequences of these adverse effects on smokers’ health. Existing studies of the economic impact of smoking have employed prevalence-based approaches, typically estimating the cost of current smoking-related morbidity and premature mortality (1, 13, 14). No study, however, has utilized an incidence-based approach, which focuses on the present value of future costs of morbidity and mortality. Consequently, little is known about the magnitude of future economic costs for smokers who are currently disease-free or about the potential economic benefits of quitting. In this article, we report estimates of both the expected economic costs of smoking and the benefits of quitting for current smokers. Incidence-based cost-of-illness procedures were first used to estimate the present value of the lifetime costs of illnesses that smokers might develop as a consequence of cigarette smoking. These costs included treatment expenses (direct costs) as well as the value of illness-related work loss due to premature death and disability (indirect costs) (11). Estimation of the expected costs of smoking ’ Funds for this research were provided by a research grant from Merrell Dow Pharmaceuticals Inc. 2 To whom reprint requests should be addressed. 377
0091-7435/84$3.00 Copyright 0 1984 by Academic Press, Inc. All rights of reproduction in any form reserved.
378
OSTER, COLDITZ,
AND KELLY
then was based upon an evaluation of the increased probability (or marginal risk) that smokers (as compared with nonsmokers) will develop these diseases in each future year of life. The economic benefits of quitting were estimated in a similar fashion, the focus in this instance being on quitters’ reduced likelihood of disease relative to continuing smokers. Therefore, in contrast to traditional cost-of-illness studies that focus on the costs of disease among the ill (1 l), our approach combined information on the costs of smoking-related illnesses with estimates of the health risks of smoking in order to generate estimates of the likely (i.e., expected) future costs of smoking and of the benefits of quitting for individuals currently disease-free. Due to limitations in data, we confined our study to three major disease conditions: lung cancer, coronary heart disease [CHD; comprising three distinct diagnostic categories: sudden death (SD), myocardial infarction (MI), and coronary insufficiency (CI)], and emphysema. The costs of smoking reported here reflect the average economic losses that current smokers are likely to generate over a lifetime because of their increased risks of developing these three diseases. Similarly, the reported benefits of quitting reflect expected reductions in economic losses as a result of lifelong reductions in the risks of developing lung cancer, CHD, and emphysema. All estimates are expressed in 1980 dollars and take into account all direct and indirect costs that smokers are likely to generate, whether they are the ones who will ultimately assume these costs or not. Our estimates of the costs of smoking and benefits of quitting are probably conservative. While lung cancer, CHD, and emphysema are unquestionably the major disease conditions that have been linked to smoking, smoking has been implicated in the etiology of other chronic and neoplastic disease conditions that are not considered in this study (20). Also, our estimates do not take into account economic costs other than those directly related to disease (e.g., the costs of residential and commercial fires), noneconomic costs, or the costs of smokingrelated diseases among nonsmokers (i.e., the costs of passive smoking). Finally, our estimates of the costs of smoking and the benefits of quitting do not include the cost of cigarettes. ANALYTICAL
FRAMEWORK
Our analytical framework likened smoking to a game of chance.3 In effect, every smoker was viewed as engaging in a lifelong series of gambles with his or her health, each occurring in a successive future year of life. The unlucky “winners” in any year’s gamble develop one of a variety of smoking-related diseases and generate its attendant economic costs, comprising treatment expenses and lost earnings. As with any game of chance, we may characterize each gamble by the average outcome experienced by its participants, or the expected value (EV). Simply put, the EV is equal to the probability of winning (or losing) multiplied by the amount that one can win (or lose). Thus, for example, the EV of a costless 3 A complete presentation of the methods employed in this study is contained in Chapter 2, “Estimating the Economic Costs of Smoking and Benefits of Quitting,” in Oster et al. (17).
COSTS OF SMOKING,
BENEFITS
OF QUITTING
379
lottery in which there is a l-in-l,000 (0.001) chance of winning $1,000 (and a 999in-l,000 chance of winning nothing) is $1 (or, $1,000 x 0.001). In the case of smoking, of course, the outcome at risk is a potential loss rather than a gain. At any point in time, each future year’s gamble may be represented by the additional likelihood that a smoker will develop a smoking-related disease during that year (given that he or she both lives and remains disease-free until that year). Corresponding to each of these future gambles, there is an associated economic cost (the sum of the direct and indirect costs of illness) that represents the amount that would be lost if an illness were to develop in that year of life. The smoking “gamble” can thus be characterized by a series of EVs, each representing an expected economic loss in a successive year of life. The costs of smoking for a current smoker are equal to the sum of these expected annual losses, each discounted to reflect its appropriate present value.4 Calculation of the costs of smoking therefore depends upon estimation of the lifetime costs of smokingrelated diseases at every possible age of onset as well as smokers’ increased likelihood of developing these diseases at each age. Just as there are expected costs of smoking resulting from the higher probability of serious illness, so there are expected economic benefits associated with reductions in the risk of disease. By definition, these benefits are equal to the losses (i.e., costs of illness) that are likely to be avoided by individuals who quit smoking. Hence, the benefits of smoking cessation may be represented by a series of expected annual,cost savings. As with the calculation of smoking costs, summation of these expected annual cost savings, each appropriately discounted to reflect the year to which it corresponds, yields an estimate of the economic benefits of quitting. If quitting resulted in an immediate elimination of all future increased risk of disease, the estimation of associated economic benefits would be a trivial undertaking. If all expected future costs of smoking could be avoided, then the dollar value of benefits simply would be equal to the amount of these costs. The elimination of marginal disease risks is not instantaneous, however; while former smokers experience significant reductions in their risks of smoking-related illnesses soon after quitting, these risks nonetheless remain higher than those of nonsmokers for a number of years. Hence, the economic benefits of quitting are equal to the difference between current smokers’ and former smokers’ expected additional costs of illness (relative to nonsmokers). Quitters’ expected cost savings in any given future year will be less than smokers’ anticipated losses in that year if the quitters experience risks of disease in excess of those experienced by nonsmokers. The benefits of quitting are thus a function of the rate at which smokers’ likelihood of disease declines in the period after quitting, and the calculation of these benefits necessitates the estimation of these reductions in annual disease risk. 4 Costs that do not accrue in the same year should not be directly summed, since they are expressed in different units of value, i.e., different years’ dollars. Discounting is a technique that expresses these costs in terms of their value in a common reference year.
380
OSTER, COLDITZ,
AND KELLY
SMOKERS’ MARGINAL RISKS OF LUNG CANCER, CORONARY HEART DISEASE, AND EMPHYSEMA Due to limitations in available data, it was assumed that smokers’ marginal risk of disease depended only upon age, sex, and amount smoked, but not on the length of time they had smoked. Estimated marginal risks of lung cancer, CHD (SD, MI, and CI), and emphysema for light, moderate, and heavy smokers are presented in Table 1, expressed in terms of the number of additional cases annually relative to nonsmokers per 100,000 population (or marginal rates of incidence), for men and women in 5-year age increments. Lung Cancer Sex- and age-specific lung cancer incidence rates for nonsmokers were estimated using data reported by Garlinkel (8). Lung cancer incidence rates for current smokers were obtained by first multiplying data on total sex- and age-specific U.S. lung cancer incidence by the estimated proportions of reported lung cancers (82.8% for men and 43.1% for women) attributable to smoking (9, 15). These totals were then divided by the number of current and former smokers in each age-sex group; the resultant rates were assumed to be average incidence rates for all current smokers. Separate sets of incidence rates for light, moderate, and heavy smokers were then generated from these average rates using data on relative risk that were contained in the 1982 Surgeon General’s Report (22). Coronary Heart Disease Sudden death, myocardial infarction, and coronary insufficiency incidence rates for nonsmokers and for light, moderate, and heavy smokers were taken directly from the Framingham Heart Study (FHS) (6, 7).5 For FHS participants over the age of 65, incidence rates were actually slightly lower for smokers than nonsmokers, but this finding was not statistically significant. Therefore, it was assumed that smoking had no effect on CHD risk past the age of 65, and zero marginal incidence rates are indicated for these smokers in Table 1. Emphysema Emphysema is almost exclusively a smokers’ disease; the lung obstruction characteristic of emphysema is almost never observed among nonsmokers (4, 5). Therefore, a zero rate of incidence was assumed for nonsmokers. Emphysema incidence rates for smokers were calculated from estimated prevalence rates obtained by dividing U.S. sex- and age-specific prevalence by the number of current and former smokers in each age-sex group (16). Incidence rates for smokers were then generated from these prevalence rates, assuming a mean survival time of 5 years past diagnosis (2, 12). The resultant estimates were assumed to be mean incidence rates for all current smokers. Separate sets of incidence rates for light, moderate, and heavy smokers were then generated using these average rates and data on relative risk reported by Ferris et al. (3). 5 For women between the ages of 35 and 44, these rates are reported for MI only.
Men 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 Women 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79
-
7 21 39 60 88 111 116 109 81
9 9 0 0 0 0 0
9 9 33 33 44 44 0 0 0
SD
13 48 125 226 273 575 784 948 989
LC
4 4 20 20 27 27 0 0 0
27 27 104 104 155 155 0 0 0
MI
0 0 33 33 0 0 0
-
9 9 17 17 12 12 0 0 0
CI
63 95 164 214 252 296 914 1,084 1,216
122 252 394 537 673 809 1,278 1,476 1,673
Em
Light smokers (less than 1 pack per day)
15 44 84 127 189 236 255 240 205
25 85 217 389 645 990 1,355 1,634 1,727
LC
Moderate
30 30 46 46 59 59 0 0 0
30 30 0 0 0 0 0
59 59 258 258 343 343 0 0 0
MI
28 28 90 90 96 96 0 0 0
SD
0 0 75 75 0 0 0
-
28 28 36 36 26 26 0 0 0
CI
100 150 260 340 400 470 1,450 1,720 1,930
180 370 580 790 990 1,190 1,880 2,170 2,460
Em
smokers (1 to 2 packs per day)
-
24 68 130 196 294 366 399 377 334
33 109 277 4% 825 1,264 1,732 2,088 2,215
LC
80 80 0 0 0 0 0
67 67 185 185 158 158 0 0 0
SD
194 194 80 80 126 126 0 0 0
97 97 486 486 571 571 0 0 0
MI
0 0 129 129 0 0 0
-
67 67 60 60 43 43 0 0 0
CI
230 345 598 782 920 1,081 3,335 3,956 4,439
324 666 1,044 1,422 1,782 2,142 3,384 3,906 4,428
Em
Heavy smokers (more than 2 packs per day)
TABLE 1 ADDITIONAL ANNUAL CASES OF LUNG CANCER (LC), SUDDEN DEATH (SD), MYOCARDIAL INFARCTION (MI), CORONARY INSUFFICIENCY (CI), AND EMPHYSEMA (EM) FOR LIGHT, MODERATE, AND HEAVY SMOKERS (PER 100,000 PERSONS)
382
OSTER, COLDITZ,
THE ECONOMIC
AND KELLY
COSTS OF SMOKING
The EV of the loss a smoker may experience in any future year of life is roughly equal to his or her marginal risk of disease in that year (presented in Table 1) multiplied by the corresponding costs of illness that may be incurred. (The lifetime costs of lung cancer, CHD, and emphysema were estimated by the authors for men and women between the ages of 35 and 79 (17), but are not reported here due to space limitations.) The costs of smoking are equal to the discounted sum of this series of expected losses. Estimates of the costs of smoking associated with increased lifelong risks of lung cancer, CHD, and emphysema for men and women between the ages of 35 and 79 are reported in Table 2. These costs were estimated in 5-year age groups for light, moderate, and heavy smokers, and were tallied in 1980 dollars using a 3% annual real (i.e., net of inflation) rate of discount and assuming a 1% future real rate of growth in labor productivity (which was used in the valuation of forgone earnings). In addition, we assumed that a smoker’s current level of cigarette consumption would remain constant throughout life; cost estimates therefore reflect the level of losses likely to result if no change occurs in smoking habits. While none of the three disease conditions may uniformly be described as the single, most costly expected consequence of smoking, the costs of smoking due to increased risk of emphysema are greatest across nearly all of the categories investigated. For example, for men ages 40-44 who are moderate smokers, the costs of smoking associated with lung cancer, CHD, and emphysema are, respectively, about $7,100, $6,500, and $19,600; the corresponding costs for women are approximately $2,000, $500, and $6,500a6The comparatively high costs of smoking associated with emphysema result from smokers’ higher marginal risks of this disease in comparison with lung cancer and CHD (see Table I), since the lifetime costs of emphysema are actually slightly lower than those of the other two disease conditions (17). Regardless of disease, the expected costs of smoking are consistently higher, controlling for age and sex, as the quantity of cigarettes smoked increases. For men ages 40-44, for example, the expected costs for heavy smokers are more than twice those for light smokers for lung cancer and emphysema ($9,055 vs $4,175, and $35,333 vs $13,348, respectively). For CHD, heavy smokers’ costs are almost five times higher ($12,282 vs $2,664). Also, almost without exception, the costs of smoking are highest for the youngest age group, controlling for sex and quantity smoked, and decline gradually with age. 6 Lower cost-of-smoking estimates for women are the products of two factors. First, existing epidemiological data sources suggest that women experience generally lower marginal disease risks than men at any given age and level of smoking (see Table 1). This could be the result of a number of factors, ranging from sex differences in smoking behavior (for example, depth of inhalation or number of “drags” per cigarette) to differences between men and women in disease etiology. Second, the costs of smoking for women are also lower because of women’s lower earning levels, which result in lower potential earnings losses. These differences in costs of smoking typically vanish by the age of 65.
214b 214b 342 245 164 55 0 0 0
939 985 968 891 788 685 541 340 210
v334
2,186 1,352 705 193 0 0 0
$2,874
$3,940 4,175 4,042 3,500 2,732 2,025 1,551 1,158 812
4,261 4,075 3,680 3,106 2,606 2,298 1,921 1,296 836
$14,753 13,348 10,530 7,188 4,313 2,607 1,850 1,318 946 5,414 5,274 4,990 4,242 3,558 3,038 2,462 1,636 1,046
$21,567 20,187 16,758 12,040 7,550 4,825 3,401 2,476 1,758 1,918 2,011 1,976 1,819 1,608 1,399 1,106 694 429
$6,714 7,114 6,887 5,965 4,656 3,450 2,642 1,974 1,384 6626 5476 859 576 365 122 0 0 0
$7,154 6,543 5,274 3,119 1,546 425 0 0 0
CHD
6,763 6,468 5,841 4,930 4,136 3,647 3,050 2,057 1,328
$21,695 19,629 15,486 10,571 6,343 3,834 2,720 1,939 1,392
Em
9,343 9,026 8,676 7,325 6,109 5,168 4,156 2,751 1,757
$35,563 33,286 27,647 19,655 12,545 7,709 5,362 3,913 2,776
Total
smokers (1 to 2 packs per day)
2,937 3,078 3,026 2,784 2,462 2,142 1,692 1.063 ‘657
2,409b 14476 1,809 1,168 695 233 0 0 0
$13,707 12,282 9,692 5,473 2,551 703 0 0 0
CHD
15,555 14,877 13,434 11,340 9,513 8,389 7,014 4,731 3,054
$39,051 35,333 27,875 19,028 11,417 6,901 4,896 3,490 2,505
Em
20,901 19,402 18,269 15,292 12,670 10,764 8,706 5,794 3,711
$61,304 56,670 46,334 32,093 19,894 11,995 8,259 6,003 4,266
Total
smokers (more than 2 packs per day)
$8,546 9,055 8,767 7,592 5,926 4,391 3,363 2,513 1,761
LC
Heavy
a All costs are in 1980 dollars, discounted at a 3% annual rate, assuming a 1% annual rate of growth in labor productivity. b CHD cost estimates for women between the ages of 35 and 44 are for myocardial infarction only.
Men 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 Women 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79
Total
LC
Em
LC
CHD
Moderate
Light smokers (less than 1 pack per day)
TABLE 2 THE ECONOMIC COSTS OF SMOKING FOR LIGHT, MODERATE, AND HEAVY SMOKERS DUE TO INCREASED RI.YK~ OF LUNG CANCER (LC), CORONARY HEART DISEASE (CHD), AND EMPHYSEMA (EM)”
384
OSTER, COLDITZ,
AND KELLY
While summation of costs across diseases will not produce precise estimates of the total costs of smoking, it can provide some indication of their likely magnitude.7 As Table 2 indicates, these total costs are sizable, particularly for heavy smokers under the age of 50. For example, male heavy smokers between the ages of 40 and 44 will generate, on average, over $56,000 in additional costs of illness during their lifetimes, while for women, these costs will be over $19,000. Although costs decline with both age and quantity of cigarettes smoked, they are significant for all smokers. QUITTING AND REDUCTIONS IN MARGINAL RISKS OF LUNG CANCER, CORONARY HEART DISEASE, AND EMPHYSEMA The economic benefits of smoking cessation are a byproduct of reductions in future likelihood of disease. Calculation of these benefits requires that these disease risk reductions be estimated. We assumed that they depended both upon the amount that one had previously smoked and the length of time since quitting. Lung Cancer
The impact of smoking cessation on future lung cancer risk was estimated on the basis of findings reported by Hammond for annual excess lung cancer mortality among male exsmokers ages 50-69 (IO). Former light smokers were found to return to nonsmokers’ risk levels approximately 5 years after quitting. Former heavy smokers, however, did not return to nonsmokers’ levels of lung cancer mortality until more than 10 years after they stopped smoking. We assumed that these results would apply to smokers of all age-sex groups, and that the effect of quitting on lung cancer incidence would be identical to its effect on lung cancer mortality. On the basis of Hammond’s findings, logit functions were used to estimate the proportion of marginal lung cancer risk that was likely to be experienced by former light, moderate, and heavy smokers in each year after they stopped smoking. The marginal risk of lung cancer in each year after quitting for an exsmoker of any given age, sex, and prior amount smoked was then calculated by multiplying a corresponding smoker’s estimated marginal risk (Table 1) by the proportion of this risk that a quitter was likely to experience. Coronary Heart Disease
The impact of smoking cessation on future CHD (SD, MI, and CI) risk also was estimated on the basis of findings reported by Hammond for male exsmokers ’ On the one hand, since other chronic and neoplastic diseases have been linked to cigarette smoking, the sum of smoking-related costs associated with lung cancer, CHD, and emphysema tends to understate significantly the actual total costs of smoking. Counterbalancing this, however, is the fact that adding the costs related to these three diseases together would tend to overstate actual total expected costs if a smoker can develop more than one of these diseases. While actual treatment expenses may or may not be less than the sum of treatment costs for each disease when two diseases are present, earnings losses definitely will be less than the sum of estimated indirect costs for each, since an individual cannot forgo the same earnings stream twice.
COSTS OF SMOKING,
BENEFITS
OF QUITTING
385
between the ages of 50 and 69 (10). Former light smokers experienced a marked decline in excess CHD mortality within one year of quitting, and the decline to nonsmokers’ risk levels was complete by the tenth year after cessation. Former heavy smokers, though, did not return to nonsmokers’ levels of CHD mortality until about 15 years after they stopped smoking. As with lung cancer, we assumed that Hammond’s reported findings would apply to smokers in all age-sex groups, and that the effect of quitting on SD, MI, and CI incidence would be identical to its effect on CHD mortality. In a manner similar to that used for lung cancer, the proportion of CHD risk that exsmokers were likely to experience in each year after quitting was estimated. These were then multiplied by the marginal risks of continuing smokers (Table 1) to yield estimated marginal SD, MI, and CI risks for former light, moderate, and heavy smokers. Emphysema
In nonsmokers, respiratory function typically declines at the rate of about 30 ml per year after age 30 (5). For smokers, the rate of decline can be two to three times as great, or about 60-100 ml per year. Once smokers quit, though, their rate of decline in respiratory function almost always reverts to that of nonsmokers (5). Despite the fact that the rapid declines in pulmonary function characteristic of emphysema stop once a smoker quits, prior loss of lung function is permanent. Because of this, former smokers may still develop emphysema several years after quitting. Normal (i.e., nonsmokers’) additional losses of pulmonary function, together with earlier smoking-related losses, may still be sufficient to result in a diagnosis of emphysema later in life. To estimate the effect of quitting on future emphysema risk, we first assumed that individuals quit voluntarily -not because of experiencing symptoms of chronic obstructive lung disease. Second, we assumed that disease incidence among exsmokers in the year immediately following cessation would be equal to that experienced by continuing smokers. Finally, in the second and all subsequent years after quitting, we assumed that disease risks would be reduced by an amount proportionately equal to the relative improvement in the rate of pulmonary function decline. Thus, for example, assuming an initial 80 ml/year decline in respiratory function, we estimated that a moderate smoker who quit would experience a marginal risk of emphysema in the second and all later years of life following cessation equal to 38% of the marginal risk experienced by a continuing smoker (30 ml/year divided by 80 ml/year). An exsmoker’s marginal risk of emphysema in any given year following cessation was then estimated by multiplying a smoker’s marginal risk (Table 1) by the proportion of this risk that quitters were likely to experience in that year. THE ECONOMIC
BENEFITS
OF QUITTING
Estimates of the benefits of quitting associated with lifelong reductions in the risks of lung cancer, CHD, and emphysema are reported in Table 3 for men and
818 776 695 598 490 347 212 124 74
$3,421 3,119 2,546 1,892 1,343 941 629 388 218
186b 164b 222 144 60 9 0 0 0
$2,331 1,909 1,240 657 226 29 0 0 0
CHD
1,999 1,889 1,663 1,383 1,155 1,023 791 524 330
$6,882 6,032 4,588 3,010 1,741 1,060 739 522 364
Em
3,003 2,829 2,580 2,125 1,705 1,379 1,003 648 404
$12,634 11,060 8,374 5,559 3,310 2,030 1,368 910 582
Total
1,489 1,362 1,185 982 741 488 292 168 96
4,304 3,325 2,391 1,657 1,1’08 699 407 221
$5,046
LC
4436 332b 446 254 99 14 0 0 0
$5,195 3,930 2,364 1,127 360 47 0 0 0
CHD
3,967 3,751 3,307 2,753 2,302 2,043 1,580 1,046 658
$12,654 11,095 8,445 5,546 3,217 1,965 1,372 968 673
Em
5,899 5,445 4,938 3,989 3,142 2,545 1,872 1,214 754
$22,895 19,329 14,134 9,064 5,234 3,120 2,071 1,375 894
Total
smokers (1 to 2 packs per day)
2,280 2,085 1,815 1,503 1,134 748 447 258 147
9556 5796 729 358 123 20 0 0 0
$8,545 5,815 3,189 1,350 387 56 0 0 0
CHD
10,359 9,800 8,645 7,205 6,034 5,357 4,145 2,743 1,724
$25,861 22,679 17,269 11,351 6,596 4,040 2,823 1,990 1,381
Em
13,594 12,464 11,189 9,066 7,291 6,125 4,592 3,001 1,871
$40,829 33,973 24,690 15,745 9,093 5,507 3,713 2,509 1,662
Total
smokers (more than 2 packs per day)
$6,423 5,479 4,232 3,044 2,110 1,411 890 519 281
LC
Heavy
0 All benefits are in 1980 dollars, discounted at a 3% annual rate, assuming a 1% annual rate of growth in labor productivity. b CHD benefit estimates for women between the ages of 35 and 44 are for myocardial infarction only.
Men 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 Women 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79
LC
Moderate
TABLE 3 FOR LIGHT, MODERATE, AND HEAVY SMOKERS DUE TO REDUCTIONS IN THE RISK OF LUNG CANCER (LC), CORONARY HEART DISEASE (CHD), AND EMPHYSEMA (EM)
Light smokers (less than 1 pack per day)
THE ECONOMIC BENEFITS OF QUI~ING
COSTS OF SMOKING,
BENEFITS OF QUITTING
387
women between the ages of 35 and 79. Our benefit estimates for light, moderate, and heavy smokers are reported in j-year age groups, and were tallied in 1980 dollars using the same real rates of discount and productivity growth that were used to calculate the costs of smoking. Benefits were measured against the costs that were likely to be generated by individuals who continued to smoke an identical amount throughout their lifetimes. In addition, we assumed that once a smoker quit, it would be for life. Our estimates of the benefits of quitting are not surprising in light of our findings regarding the costs of smoking. The greatest benefits were found to be associated with reduced risks of developing emphysema, although they are sizable irrespective of disease condition. For example, for men ages 40-44 who are moderate smokers, the benefits of quitting associated with reduced risks of lung cancer, CHD, and emphysema are, respectively, about $4,300, $3,900, and $11,100; the corresponding figures for women are approximately $1,500, $300, and $3,800. As expected, these benefits are consistently higher for those who were formerly heavy smokers, and are greatest for persons in the youngest age groups. Summation of benefits across the three diseases suggests that the total benefits of quitting are sizable.8 For male heavy smokers under the age of 45, the present value of total lifetime dollar benefits is about $34,000, and for women, the corresponding total is over $12,000. Even for the very oldest age groups (i.e., age 70 and over), the total benefits of quitting are by no means inconsequential. For men, they range from about $600 to slightly over $2,500; for women, the range is from $400 to about $3,000. DISCUSSION
This study has found that the expected costs of cigarette smoking for individual smokers are substantial. While these costs vary with sex, age, and the amount smoked, there was no group of smokers that was not expected to generate sizable losses. Furthermore, the results of this study have shown that, at any age, it literally pays to stop smoking, since the benefits of quitting are also sizable. The relative effectiveness of smoking cessation may be conveniently assessed by computing ratios of the overall benefits of quitting to the total costs of smoking.9 What each reveals is the expected proportion of smoking-related losses that a given smoker can avoid by quitting. In a sense, these ratios indicate the extent of “cost recovery” possible; the higher this ratio, the greater the relative benefits of quitting. 8 Considerations similar to those noted in footnote 7 apply to the addition of benefits-of-quitting estimates across diseases. 9 While these cost recovery ratios are equal to the ratio of the benefits of quitting to the costs of smoking, it is not a benefit-cost ratio in the traditional sense. A benefit-cost ratio compares the benefits and costs of one specific course of action, while the ratio of the benefits of quitting to the costs of smoking compares the results of two alternative courses of action (i.e., quitting vs continuing to smoke). Related to this difference is the fact that our cost recovery ratios will always be less than 1 since an exsmoker’s risk of developing a smoking-related disease does not return to that of a nonsmoker for a number of years after smoking cessation. Consequently, the benefits of quitting for an exsmoker can never be as great, in absolute terms, as the costs of continuing to smoke.
OSTER, COLDITZ,
388
AND KELLY
TABLE 4 TOTAL COST RECOVERY RATIOS FOR LIGHT, MODERATE, AND HEAVY SMOKERS
Men 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 Women 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79
Light smokers
Moderate smokers
Heavy smokers
0.586 0.548 0.500 0.462 0.438 0.421 0.402 0.368 0.331
0.644 0.581 0.511 0.461 0.417 0.405 0.386 0.351 0.329
0.666 0.608 0.511 0.491 0.457 0.459 0.450 0.418 0.322
0.555 0.536 0.517 0.501 0.479 0.454 0.407 0.396 0.386
0.631 0.603 0.569 0.545 0.514 0.493 0.450 0.441 0.429
0.650 0.642 0.613 0.593 0.576 0.569 0.528 0.518 0.504
Estimated cost recovery ratios for men and women are presented in Table 4. Although these ratios are highest for younger smokers, it is apparent that it is literally never too late to stop smoking. While quitters below the age of 45 are likely to avoid between 54 and 67% of expected lifetime losses due to smoking, even those over the age of 70 are likely to avoid between 32 and 52% of these expected losses. Our findings have many potential uses. For individual smokers, they may provide yet another powerful argument against smoking. Similarly, physicians may find them useful in encouraging their patients to quit smoking. Corporate decision makers also may find our estimates useful in their attempts to evaluate the cost effectiveness of employer-sponsored smoking cessation programs. Finally, our study undoubtedly will prove useful to policymakers in government as they increasingly turn their attention to the economic burden of the health consequences of cigarette smoking and the question of who should ultimately pay these staggering costs. REFERENCES 1. Cady, B. Cost of smoking. New Engl. J. Med. 308, 1105 (1983). 2. Diener, C. F., and Burrows, B. Further observations on the course and prognosis of chronic obstructive lung disease. Amer. Rev. Resp. Dis. 11, 719-724 (1975). 3. Ferris, B. G., Chen, S. P., and Murphy, L. H. Chronic nonspecific respiratory disease in Berlin, New Hampshire: A further follow-up study. Amer. Rev. Resp. Dis. 113, 475-485 (1976). 4. Fletcher, D., and Peto, R. The natural history of chronic airtlow obstruction. Brit. Med. J. 1, 1645-1648 (1977).
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BENEFITS
OF QUITTING
389
5. Fletcher, D., Peto, R., Tinker, C., and Speizer, F. E. “The Natural History of Chronic Bronchitis and Emphysema, An Eight-Year Study of Early Chronic Obstructive Lung Disease in Working Men in London.” Oxford Univ. Press, Oxford, 1976. 6. “The Framingham Study. An Epidemiological Investigation of Cardiovascular Disease, Section 26: Some Characteristics Related to the Incidence of Cardiovascular Disease and Death; Framingham Study, 16-Year Follow-up.” Department of Health, Education, and Welfare, Washington, D.C., 1970. 7. “The Framingham Study. An Epidemiological Investigation of Cardiovascular Disease, Section 30: Some Characteristics Related to the Incidence of Cardiovascular Disease and Death: Framingham Study, l&Year Follow-up.” Department of Health, Education, and Welfare, Washington, D.C., 1974. 8. Garfinkel, L. Cancer mortality in non-smokers: Prospective study of the American Cancer Society. J. Natl. Cancer Inst. 65, 1169-1173 (1980). 9. Hammond, E. C., and Seidman, H. Smoking and cancer in the United States. Pro. Med. 9, 169173 (1980). 10. Hammond, E. C. Smoking in relation to the death rates of one million men and women, in “Epidemiologic Approaches to the Study of Cancer and Other Chronic Diseases” (W. Haenszel, Ed.), National Cancer Institute Monograph No. 19. U.S. Govt. Printing Office, Washington, D.C., 1966. 11. Hartunian, N. S., Smart, C. N., and Thompson, M. S. “The Incidence and Economic Costs of Major Health Impairments.” Heath, Boston, 1981. 12. Kleinbaum, D. G., Kupper, L. L., and Morgenstern, H. “Epidemiologic Research, Principles and Quantitative Methods.” Lifetime Learning Pub., Belmont, Calif., 1982. 13. Lute, B. R., and Schweitzer, S. 0. Smoking and alcohol abuse: A comparison of the economic consequences. New Engl. J. Med. 298, 569-571 (1978). 14. Lute, B. R., and Schweitzer, S. 0. The economics of smoking-induced illness, in “Research on Smoking Behavior” (M. E. Jarvik, J. W. Cullen, E. R. Gritz, et al., Eds.), National Institute on Drug Abuse Research Monograph 17. U.S. Govt. Printing Office, Washington, D.C., 1977. 15. National Cancer Institute. “Surveillance, Epidemiology, and End Results: Incidence and Mortality Data, 1973-1977,” National Cancer Institute Monograph No. 57, NIH Pub. No. 81-2330. National Institutes of Health, Washington, D.C., 1981. 16. National Center for Health Statistics. “Prevalence of Selected Chronic Respiratory Conditions, United States, 1970.” Vital and Health Statistics, Series 10, No. 84, DHEW Pub. No. (HRA) 74-1511, 1974. 17. Oster, G., Colditz, G. A., and Kelly, N. L. “The Economic Costs of Smoking and Benefits of Quitting.” Heath, Boston, 1984. 18. Rice, D. P. “Estimating the Cost of Illness,” Health Economics Series, No. 6, PHS Pub. No. 947-6. U.S. Govt. Printing Office, Washington, D.C., 1966. 19. U.S. Dept. of Health, Education and Welfare. “Report of the Advisory Committee to the Surgeon General of the Public Health Service,” DHEW Pub. No. (PHS) 1103. U.S. Govt. Printing Office, Washington, D.C., 1964. 20. U.S. Dept. of Health, Education and Welfare. “Smoking and Health-A Report of the Surgeon General,” DHEW Pub. No. (PHS) 79-50066. U.S. Govt. Printing Office, Washington, D.C., 1979. 21. U.S. Dept. of Health and Human Services. “The Changing Cigarette-A Report of the Surgeon General,” DHHS Pub. No. (PHS) 81-50156. U.S. Govt. Printing Office, Washington, D.C., 1981. 22. U.S. Department of Health and Human Services. “The Health Consequences of Smoking: Cancer-A Report of the Surgeon General,” DHHS Pub. No. (PHS) 82-50179. U.S. Govt. Printing Office, Washington, D.C., 1982.