Perspectives in Disease Prevention and Health Promotion Smoking-Attributable Mortality and Years of Potential Life Lost -- United States, 1984

As part of its commemoration of CDC's 50th anniversary, MMWR is reprinting selected MMWR articles of historical interest to public health, accompanied by a current editorial note. Reprinted below is the report published October 30, 1987, which analyzed smoking-attributable mortality and years of potential life lost for 1984, followed by a contemporary editorial note.

Cigarette smoking has been identified as the chief avoidable cause of death in the United States (1). Several estimates of mortality attributable to cigarette smoking have been reported, including 270,000 deaths for 1980 (2) and 314,000 deaths for 1982 (3). Published estimates vary considerably because of changing mortality rates, decreasing smoking rates, and differences in methods used. Smoking-attributable mortality and years of potential life lost (YPLL) for 1984 are analyzed in this report.

Relative risk (RR) estimates for smoking-related diseases and prevalence estimates of current, former, and never smokers among adults greater than or equal to 20 years of age were used to calculate the smoking-attributable fraction (SAF) and smoking-attributable mortality for 19 underlying causes of death (2) (Table_1).* Age-, sex-, and race-specific mortality data for 1984 were obtained from National Center for Health Statistics reports. Age-, sex-, and race-specific smoking prevalence rates were obtained from the 1985 Current Population Survey (Supplement) of the Bureau of the Census (Office on Smoking and Health, CDC, unpublished data). Years of potential life lost were calculated to age 65 according to previously described methods (6). Age-adjusted smoking-attributable mortality and YPLL rates were calculated by the direct method, with the 1984 U.S. population used as the standard.

For deaths among adults, the disease-specific SAFs are derived from RR estimates for current and former smokers that are weighted averages from four prospective studies (7-10). RR estimates for women based on these studies may be lower than the current RRs for many of the specific smoking-related diseases among women. However, the SAF for lung cancer among women (0.75) has been updated based on RR estimates from more recent mortality data (11). Race-specific RR estimates for smoking-attributable diseases were not available.

For four pediatric diagnoses, the mortality attributed to maternal smoking during pregnancy for children less than 1 year of age was determined. These calculations used RR estimates from McIntosh (12) and current smoking prevalence among women 20-64 years of age as a proxy for the percentage of pregnant women who smoke. The RR (1.50) for sudden infant death syndrome from McIntosh (12) was used, but the RR (1.76) for total infant mortality reported by McIntosh was used to calculate the SAF for only three specific infant death categories (short gestation/low birthweight, respiratory distress syndrome, and other respiratory conditions).

An estimated 315,120 deaths and 949,924 YPLL before age 65 years resulted from cigarette smoking in 1984 (Table_2). The smoking-attributable mortality rate among men is more than twice the rate among women, and the rate among blacks is 20% higher than the rate among whites (Table_3). The smoking-attributable YPLL rate among men is more than twice the rate among women, and the rate among blacks is more than twice the rate among whites (Table_3).

Reported by: Office on Smoking and Health, Center for Health Promotion and Education, CDC.

editorial note: The total smoking-attributable mortality and YPLL reported here is similar to that cited in previous reports (2,3), showing that the disease impact of smoking in the United States continues to be enormous despite recent declines in the prevalence of smoking. These figures do not include mortality and YPLL due to peripheral vascular disease (for which specific RR estimates are generally lacking), cancer at unspecified sites, cigarette-caused fires, or involuntary (passive) smoking. In 1984, an estimated 1,570 deaths were attributed to cigarette-initiated fires (13); an estimated 3,825 nonsmokers per year die from lung cancer attributed to involuntary smoking (14). When the figures for fires and involuntary smoking are included, the estimated total of smoking-attributable deaths in the United States in 1984 is 320,515, or 15.7% of all (2,039,369) U.S. deaths. Total smoking-attributable YPLL (949,924) represents 8.1% of all (11,761,000) U.S. YPLL before age 65 (excluding YPLL due to cigarette-caused fires or involuntary smoking).

Among blacks, the smoking-attributable mortality (32,779) represents 13.9% of total 1984 mortality (235,884), whereas the smoking-attributable mortality for whites (279,636) was 15.7% of total 1984 mortality (1,781,897), excluding deaths due to fires or involuntary smoking. However, the smoking-attributable mortality rate and YPLL rate were higher among blacks than among whites. These differences in rates reflect a higher prevalence of smoking and a higher mortality rate from smoking-related diseases among blacks. Higher YPLL rates among blacks may also reflect more smoking-attributable deaths at earlier ages. Because blacks tend to smoke fewer cigarettes per day than whites (15,16), the difference in smoking-attributable mortality and YPLL rates between blacks and whites may be slightly overestimated. On the other hand, the RR of smoking-related diseases among blacks may be higher than the RR estimates used here because of increased interactions between smoking and other risk factors, different tar and nicotine exposures, or different smoking patterns. Still, these findings support previously cited concerns regarding the increased burden of smoking-related disease among blacks (17).

Smoking prevalence for 1985 was used to calculate the SAFs in this study. However, the 1984 smoking-related mortality is a result of a higher smoking prevalence during the 1950s, '60s, and '70s, the decades during which these diseases were developing. Therefore, the SAFs used here are conservative.

CDC has examined YPLL before age 65 years since 1979 (6). In this study, most smoking-related deaths (218,691, or 69.4%) occurred among persons greater than or equal to 65 years of age. Thus, the smoking-attributable YPLL among persons less than 65 reported here (949,924) is substantially lower than the 3.6 million smoking-attributable YPLL calculated when the average life expectancy in the United States is used for calculating YPLL for 1984.

Group-specific calculations such as these are possible for states and other defined populations if mortality and smoking prevalence data for those populations are available. A computer program has recently been developed to aid in calculating mortality and YPLL attributed to cigarette smoking (18). CDC is now collaborating with all 50 state health departments, Puerto Rico, and the District of Columbia to perform similar studies. Results from this project will be reported in 1988. references

1. Office on Smoking and Health. The health consequences of smoking: cancer -- a report of the Surgeon General. Rockville, Maryland: US Department of Health and Human Services, Public Health Service, 1982:xi; DHHS publication no. (PHS)82-50179.

2. Rice DP, Hodgson TA, Sinsheimer P, Browner W, Kopstein AN. The economic costs of the health effects of smoking, 1984. Milbank Mem Fun Q 1986;64:489-547.

3. Office of Technology Assessment. Smoking-related deaths and financial costs. OTA Staff Memorandum. Health Program, U.S. Congress, 1985.

4. Walter SD. The estimation and interpretation of attributable risk in health research. Biometrics 1976;32:829-49.

5. Lilienfeld AM, Lilienfeld DE. Foundations of epidemiology. 2nd ed. New York: Oxford University Press, 1980.

6. CDC. Premature mortality in the United States: public health issues in the use of years of potential life lost. MMWR 1986;35(suppl 2S).

7. Hammond EC. Smoking in relation to the death rates of one million men and women. In: Haenszel WM, ed. Epidemiological approaches to the study of cancer and other chronic diseases. Bethesda: National Cancer Institute, US Department of Health, Education, and Welfare, Public Health Service, 1966:127-204. (NCI Monograph no. 19).

8. Doll R, Peto R. Mortality in relation to smoking: 20 years' observations on male British Doctors. Br Med J 1976;2:1525-36.

9. Doll R, Gray R, Hafner B, Peto R. Mortality in relation to smoking: 22 years' observations on female British doctors. Br Med J 1980;280:967-71.

10. Cederl�f R, Friberg L, Lundman T. The interactions of smoking, environment, and heredity and their implications for disease etiology: a report of epidemiological studies on the Swedish twin registries. Acta Med Scand 1977;612(suppl):7-128.

11. American Cancer Society. 1986 cancer facts and figures. New York: American Cancer Society, 1986:17.

12. McIntosh ID. Smoking and pregnancy: attributable risks and public health implications. Can J Public Health 1984;75:141-8.

13. Hall JR Jr. Expected changes in fire damages from reducing cigarette ignition propensity. Report No. 5, Technical Study Group, Cigarette Safety Act of 1984. Quincy, Massachusetts: National Fire Protection Association, Fire Analysis Division, 1987.

14. National Academy of Sciences. Environmental tobacco smoke: measuring exposures and assessing health effects. Washington, DC: National Academy Press, 1986: Appendix D.

15. CDC. Cigarette smoking in the United States, 1986. MMWR 1987;36:581-5.

16. National Center for Health Statistics. Health, United States, 1986. Washington, DC: US Department of Health and Human Services, Public Health Service, 1986:126; DHHS publication no. (PHS)87-1232.

17. CDC. Cigarette smoking among blacks and other minority populations. MMWR 1987;36:404-7.

18. Shultz JM. SAMMEC: smoking-attributable mortality, morbidity, and economic costs (computer software and documentation). Minnesota: Center for Nonsmoking and Health, Minnesota Department of Health, 1986.

    Editorial Note

Editorial Note 1997: In 1987, CDC published the preceding report that provided a detailed and comprehensive estimate of the number of deaths attributed to cigarette smoking in the United States. Using the attributable fraction, which measures the magnitude of a public health problem accounted for by an etiologic agent, CDC was able to quantify the impact of smoking. This method established that smoking was the leading cause of preventable deaths in the United States (1). As a result, increased emphasis was placed on decreasing the health burden caused by tobacco use and on reducing cigarette smoking. Since this SAM estimate was published in 1987, continued research has increased understanding of the health risks associated with tobacco use, including nicotine addiction and the recognition that addiction begins in childhood. Public health programs have responded by focusing on preventing tobacco use among adolescents, assisting in tobacco-use cessation, and protecting nonsmokers from environmental tobacco smoke. This contemporary editorial note reviews previous SAM estimates, presents new SAM estimates for 1990-1994, and discusses future implications.

SAM and YPLL estimates for the United States published since the first estimate for 1984 include 390,000 deaths for 1985, 434,000 deaths and 6 million YPLL before age 85 for 1988, and 418,000 deaths and 5 million YPLL to life expectancy for 1990 (2). SAM and YPLL also have been estimated for all 50 states and the District of Columbia for 1985 and for 1990 (3). Although all estimates were calculated by the same equation used for the SAF, the data sources, study populations, and causes of death have changed. The Smoking-Attributable Mortality, Morbidity, and Economic Costs (SAMMEC) software program has also been used for calculating these estimates (2).

Since 1989, RR estimates for calculating SAM and YPLL have been obtained from the American Cancer Society's Cancer Prevention Study II (CPS-II) for 1982-1986 (4). The CPS-II was selected, in part, because it is the largest prospective U.S. study that has collected data on the relation between smoking and mortality (4). Recent SAM estimates for adults have been limited to persons aged greater than or equal to 35 years because the CPS-II study population was restricted to this age range. Deaths from stomach cancer and ulcers were dropped from the calculation of SAM because a causal relation has not been established (4). Conversely, the cardiovascular and respiratory disease categories were expanded to include the International Classification of Diseases, Ninth Revision {ICD-9}, codes 390-398, 415-417, 420-429, 442-448, 010-012, and 493. The CPS-II data also enabled the calculation of the RR for smoking and cerebrovascular disease, which declines with age (4), for two age groups (35-64 years and greater than or equal to 65 years).

Cigarette smoking remains the leading preventable cause of death in the United States. The same methods and data sources that were used to calculate the 1990 SAM and YPLL (2)** were used for the 1990-1994 calculations, which indicated that 2,153,700 deaths (1,393,200 men and 760,400 women; total annual average: 430,700 deaths) were attributed to smoking (19.5% of all deaths). A total of 906,600 of these deaths resulted from cardiovascular diseases; 778,700, from neoplasms; 454,800, from nonmalignant respiratory diseases; 7900, from diseases among infants; and 5500, from smoking-related fires. Lung cancer (616,800 deaths), ischemic heart disease (IHD) (490,000 deaths), and chronic airway obstruction (270,100 deaths) accounted for most deaths. During 1990-1994, cigarette smoking resulted in 5,732,900 YPLL before age 65 years and in 28,606,000 YPLL to life expectancy.

During 1990-1994, estimates of SAM were higher among men than among women, reflecting their longer duration and higher prevalence of smoking and greater numbers of cigarettes smoked per day (6). Annual SAM rates will probably remain stable if current trends in smoking prevalence among adults continue. Although the prevalence of smoking among persons aged greater than or equal to 35 years decreased from 1985 to 1990 (28.4% to 24.1%), during 1990-1994, smoking prevalence remained relatively constant -- at 23.6%-24.8% (CDC, unpublished data). However, the prevalence of smoking among U.S. adolescents has been increasing since 1992 (7). If these smoking patterns continue into adulthood, SAM and YPLL are expected to increase. Assuming that one third of adult smokers, 10% of former smokers, and 5.3 million persons aged less than 18 years die from smoking and that current smoking patterns continue, an estimated 25 million persons alive today will die prematurely from smoking-related illnesses (7,8).

Lung cancer has been and probably will continue to be the leading cause of SAM because, although lung cancer death rates are decreasing among men, rates are continuing to increase among women (9). Among women, death rates for lung cancer have surpassed those for breast cancer since 1987 (9). In addition, because recent trends indicate a slowing of the decline in IHD mortality, IHD will probably remain a major contributor to SAM (9).

SAM and YPLL may be underestimated for several reasons (2); recent studies have addressed two of these reasons. First, SAM and YPLL estimates are based on the prevalence of current and former smokers in the current year; however, the deaths that occur during a given year are primarily among persons who began smoking 30-50 years earlier (10), many of whom have quit smoking (10). Including these persons in the prevalence estimates of former smokers may decrease the SAF because the summary measure of risk for former smokers does not reflect their increased likelihood of dying from a smoking-related disease (4). Among whites, expanding the classification of smoking to include information on duration and number of cigarettes smoked per day resulted in 10% larger SAM estimates for IHD than SAM estimates in which smoking was categorized as current, former, and never (10). Second, the SAM estimates do not include mortality caused by cigar smoking, pipe smoking, or smokeless tobacco use. Approximately 1000 deaths were attributable to pipe smoking in 1991 (11).

Although SAM and YPLL estimates are not adjusted for confounders (2-4), a recent study has documented little change in SAM estimates after adjustment for confounders (12). Among whites, SAM estimates for the combined disease categories of lung cancer, IHD, bronchitis/emphysema, chronic airway obstruction, and cerebrovascular disease were 2% higher than age-adjusted estimates after adjustment for relevant confounders including age, education, alcohol intake, diabetes, and hypertension (12).

Cigarette smoking has resulted in approximately 10 million deaths since the first Surgeon General's report on smoking and health in 1964 (2,4,13). In 1993, $50 billion in medical costs were attributable to smoking (14). The human and economic costs of smoking will continue to accumulate until the completely effective implementation of public health efforts to prevent initiation, to promote cessation, and to protect nonsmokers from the adverse effects of environmental tobacco smoke. Examples of such efforts include Food and Drug Administration regulations to restrict youth access to tobacco and to reduce the appeal of cigarette advertising to youth (7); comprehensive state-based efforts, including tax increases and earmarked funding for tobacco-use prevention and mass media campaigns similar to those in Massachusetts and California (15); physician adherence to the Agency for Health Care Policy and Research's smoking cessation guidelines (8); institutional adoption of the Guidelines for School Health Programs to Prevent Tobacco Use and Addiction (16); and clean indoor-air policies that protect nonsmokers. 1997 Editorial Note by Ann M Malarcher, PhD, Jeffrey H Chrismon, Gary A Giovino, PhD, Michael P Eriksen, ScD, Office on Smoking and Health, National Center for Chronic Disease Prevention and Health Promotion, CDC.

References

1. McGinnis JM, Foege WH. Actual causes of death in the United States. JAMA 1993;270:2207-12.

2. CDC. Cigarette smoking-attributable mortality and years of potential life lost -- United States, 1990. MMWR 1993;42:645-9.

3. Nelson DE, Kirkendall RS, Lawton RL, et al. Surveillance for smoking-attributable mortality and years of potential life lost, by state -- United States, 1990. MMWR 1994;43(no. SS-1):1-8.

4. US Department of Health and Human Services. Reducing the health consequences of smoking: 25 years of progress -- a report of the Surgeon General. Washington, DC: US Department of Health and Human Services, Public Health Service, CDC, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 1989.

5. National Institute on Drug Abuse. Summary tables: annualized estimates from the National Pregnancy and Health Survey. Rockville, Maryland: US Department of Health and Human Services, Public Health Service, National Institutes of Health, National Institute on Drug Abuse, 1994.

6. Giovino GA, Schooley MW, Zhu B-P, et al. Surveillance for selected tobacco-use behaviors -- United States, 1900-1994. MMWR 1994;43(no. SS-3).

7. CDC. Projected smoking-related deaths among youth -- United States. MMWR 1996;45:971-4.

8. CDC. State specific prevalence of cigarette smoking -- United States, 1995. MMWR 1996;45:962-6.

9. National Center for Health Statistics. Health, United States, 1995. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1996.

10. Schulman J, Mowery PD, Pierce BK, et al. Methodologic issues in estimating smoking attributable mortality. Atlanta, Georgia: Battelle, Centers for Public Health Research and Evaluation, 1995.

11. Nelson DE, Davis RM, Chrismon JH, Giovino GA. Pipe smoking in the United States, 1965-1991: prevalence and attributable mortality. Prev Med 1996;25:91-9.

12. Schulman J, Epstein L, Mowery PD, Pierce B, Euskirchen E, Abed J. Smoking attributable mortality: control for confounding. Atlanta, Georgia: Battelle, Centers for Public Health Research and Evaluation, 1997.

13. US Department of Health, Education, and Welfare. Smoking and health report of the advisory committee to the Surgeon General of the Public Health Service. Washington, DC: US Department of Health, Education, and Welfare, Public Health Service, 1964.

14. CDC. Medical-care expenditures attributable to cigarette smoking -- United States, 1993. MMWR 1994;43:469-72.

15. CDC. Cigarette smoking before and after an excise tax increase and an antismoking campaign -- Massachusetts, 1990-1996. MMWR 1996;45:966-70.

16. CDC. Guidelines for school health programs to prevent tobacco use and addiction. MMWR 1994;43(no. RR-2).

* The equation for calculating the smoking-attributable fraction of each disease category is: SAF={p0 + p1(RR1) + p2(RR2)} - 1/{p0 + p1(RR1) + p2(RR2)} where p0=percentage of never smokers, p1=percentage of current smokers, p2=percentage of former smokers, RR1=relative risk for current smokers (relative to never smokers), and RR2=relative risk for former smokers (relative to never smokers) (4). This formula is derived from the standard attributable risk (AR) formula (5): AR=p(RR - 1)/{p(RR - 1) + 1}. ** Except for the prevalence of smoking among pregnant women in the United States for 1992 through 1994, which was estimated from the 1992 1993 National Pregnancy and Health Survey (5).

TABLE 1. Total mortality, weighted smoking-attributable fractions (SAF), and smoking-attributable mortality (SAM), by disease category and sex -- United States, 1984
=======================================================================================================================================================================
                                                                       Males                         Females
                                                              --------------------------   -------------------------------
Disease Category *                                              Deaths      SAF   SAM      Deaths       SAF          SAM        Total SAM +
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------
Adults >=20 years old
Neoplasms:
140-149 Lip, oral cavity, pharynx                               5,754    0.688    3,958       2,689     0.413        1,110          5,068
150     Esophagus                                               6,310    0.589    3,717       2,345     0.536        1,257          4,974
151     Stomach                                                 8,468    0.172    1,455       5,772     0.254        1,467          2,922
157     Pancreas                                               11,513    0.300    3,459      11,634     0.142        1,653          5,112
161     Larynx                                                  2,959    0.806    2,385         664     0.413          274          2,660
162     Trachea, lung, bronchus                                82,459    0.796   65,659      36,227     0.750       27,170         92,829
180     Cervix uteri                                                0      0.0        0       4,562     0.369        1,685          1,685
188     Urinary bladder                                         6,597    0.371    2,447       3,114     0.274          853          3,299
189     Kidney, other urinary                                   5,424    0.243    1,319       3,403     0.118          403          1,722

Circulatory diseases:
401-405 Hypertension                                           13,464    0.156    2,099      17,855     0.148        2,645          4,744
410-414 Ischemic heart disease =age 65                    211,003    0.159   33,461     224,756     0.075       16,816         50,276
427.5   Cardiac arrest                                         19,392    0.399    7,745      17,296     0.344        5,950         13,695
430-438 Cerebrovascular disease                                59,185    0.096    5,692      88,285     0.139       12,228         17,920
440     Arteriosclerosis                                        9,235    0.238    2,200      15,216     0.315        4,797          6,996
441     Aortic aneurysm                                        10,323    0.624    6,444       4,791     0.468        2,244          8,689

Respiratory Diseases:
480-487 Pneumonia, influenza                                   28,774    0.208    5,986      28,935     0.093        2,679          8,664
491-492 Chronic bronchitis, emphysema                          10,708    0.850    9,097       5,517     0.694        3,831         12,928
496     Chronic airways obstruction                            31,240    0.850   26,541      16,625     0.694       11,545         38,085

Digestive diseases:
531-534 Ulcers                                                  3,251    0.479    1,556       3,365     0.445        1,497          3,053

Pediatric diseases <1 year old
765     Short gestation     low birthweight                     1,729    0.182      314          33     0.182          279            593
769     Respiratory distress syndrome                           2,178    0.182      396       1,379     0.182          251            647
770     Other respiratory conditions of newborn                 1,982    0.182      360       1,515     0.182          275            636
798.0   Sudden infant death syndrome                            3,176    0.128      405       2,069     0.128          264            669

Total +                                                                         209,057                            106,063        315,120
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------
* International Classification of Disease, ninth revision.
+ Sums may not equal total because of rounding.
=======================================================================================================================================================================

TABLE 2. Estimated smoking-attributable mortality and years of potential life lost (YPLL) *,
by race and sex -- United States, 1984
===============================================================================================
                                  Mortality                             YPLL
                         ------------------------------    -----------------------------
                           Males    Females     Total +      Males    Females     Total +
-----------------------------------------------------------------------------------------------
Whites                   184,296     95,340    279,636    489,827    199,590    689,418
Blacks                    22,647     10,131     32,779    129,952     63,473    193,425
-----------------------------------------------------------------------------------------------
Total population &       209,057    106,063    315,120    661,651    288,273    949,924
-----------------------------------------------------------------------------------------------
* YPLL before age 65.
+ Sums may not equal total because of rounding.
& Includes whites, blacks, and recial category "other."
===============================================================================================

TABLE 3. Age-adjusted smoking-attributable mortality rates * and years of potential life
lost (YPLL) rates +, by race and sex -- United States, 1984
============================================================================================
                                      Mortality rate                   YPLL
                               ----------------------------   --------------------------
                                Males    Females    Total +    Males    Females   Total
--------------------------------------------------------------------------------------------
Whites                          189.7       64.2     119.0     5.56       2.17    3.81
Blacks                          236.5       75.5     143.2    12.07       4.85    8.14
Total population &              192.6       68.0     133.2     6.53       2.71    4.56
--------------------------------------------------------------------------------------------
* Per 100,000 persons (population data from 1984 U.S. Census).
+ YPLL before age 65/1,000 persons <65 years (population data from 1984 U.S. Census).
& Includes whites, blacks, and racial category "other."
============================================================================================

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