CDC's April 2002 Report On Smoking
Estimates of Selected Health Consequences of Cigarette Smoking Were Reasonable
Gao ID: GAO-03-942R July 17, 2003
Despite a recent decline in the population that smokes, smoking is considered the leading cause of preventable death in this country. According to the Centers for Disease Control and Prevention (CDC), over 2 million deaths in the 5-year period from 1995 through 1999 were attributable to cigarette smoking. CDC, part of the Department of Health and Human Services (HHS), is a primary source of information on the health consequences of smoking tobacco. CDC reported its most recent estimates of selected health consequences of cigarette smoking in an April 2002 issue of its publication Morbidity and Mortality Weekly Report. CDC reported that, on average, over 440,000 deaths, 5.6 million years of potential life lost, $82 billion in mortality-related productivity losses, and $76 billion in medical expenditures were attributable to cigarette smoking each year from 1995 through 1999. CDC and others tasked with making such estimates face challenges. They build estimates on a set of assumptions and make choices about the data sources and methods used, each of which may have limitations that must be weighed against its advantages. Policymakers at both the state and federal levels have relied on estimates like these in considering bans on smoking in public places, taxes on cigarettes, litigation to recoup medical expenditures, and other matters concerning tobacco. Thus it is essential that the estimates CDC provides are sound and that their limitations are clear. In recognition of this, Congress asked us to review CDC's April 2002 report and determine whether its estimates of selected health consequences of cigarette smoking were reasonable. Specifically, we examined CDC's estimates of (1) deaths and years of potential life lost and (2) mortality-related productivity losses and medical expenditures attributable to cigarette smoking.
In summary, CDC's estimates of the average number of deaths and years of potential life lost each year due to cigarette smoking were reasonable. The estimates were based on the increases in deaths from 23 causes that were linked to cigarette smoking. The linkages of cigarette smoking to increased mortality due to the included causes, such as lung cancer or cardiovascular disease, had been well established by the Surgeon General. CDC used the method generally accepted among epidemiologists for estimating the increased deaths attributable to cigarette smoking. The data sources CDC used were the best available and included: the largest study of smoking behavior and health status available for data on the risk of death in smokers relative to nonsmokers; the National Health Interview Survey of over 97,000 persons for data on the prevalence of smoking; and death certificates compiled from all states for mortality data. CDC recognized and handled appropriately the limitations in the data from these sources. CDC's estimates of the annual mortality-related productivity losses and medical expenditures due to cigarette smoking also were reasonable. CDC estimated productivity losses associated with the years of potential life lost using assumptions about employment and earnings that are generally accepted among economists, well-established methods for extrapolating from present earnings to earnings that would be made in the future, and large federal data sources on earnings. The assumptions that CDC made and the methods it used to estimate medical expenditures were also generally accepted among health care economists. CDC relied on the most comprehensive data available on medical expenditures, the federally sponsored National Medical Expenditure Survey of over 38,000 persons. For both productivity losses and medical expenditures, CDC recognized and handled appropriately the limitations in the data.
GAO-03-942R, CDC's April 2002 Report On Smoking: Estimates of Selected Health Consequences of Cigarette Smoking Were Reasonable
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July 16, 2003:
The Honorable Richard Burr:
House of Representatives:
Subject: CDC's April 2002 Report On Smoking: Estimates of Selected
Health Consequences of Cigarette Smoking Were Reasonable:
Dear Mr. Burr:
Despite a recent decline in the population that smokes, smoking is
considered the leading cause of preventable death in this country.
According to the Centers for Disease Control and Prevention (CDC), over
2 million deaths in the 5-year period from 1995 through 1999 were
attributable to cigarette smoking. CDC, part of the Department of
Health and Human Services (HHS), is a primary source of information on
the health consequences of smoking tobacco. CDC reported its most
recent estimates of selected health consequences of cigarette smoking
in an April 2002 issue of its publication Morbidity and Mortality
Weekly Report.[Footnote 1] CDC reported that, on average, over 440,000
deaths, 5.6 million years of potential life lost, $82 billion in
mortality-related productivity losses, and $76 billion in medical
expenditures were attributable to cigarette smoking each year from 1995
through 1999. (See enclosures I and II.):
CDC and others tasked with making such estimates face challenges. They
build estimates on a set of assumptions and make choices about the data
sources and methods used, each of which may have limitations that must
be weighed against its advantages. Policymakers at both the state and
federal levels have relied on estimates like these in considering bans
on smoking in public places, taxes on cigarettes, litigation to recoup
medical expenditures, and other matters concerning tobacco. Thus it is
essential that the estimates CDC provides are sound and that their
limitations are clear. In recognition of this, you asked us to review
CDC's April 2002 report and determine whether its estimates of selected
health consequences of cigarette smoking were reasonable. Specifically,
we examined CDC's estimates of (1) deaths and years of potential life
lost and (2) mortality-related productivity losses and medical
expenditures attributable to cigarette smoking.
To determine whether CDC's estimates were reasonable, we reviewed CDC's
approach and alternative approaches to developing them. Specifically,
we reviewed CDC's assumptions, methods, and data sources; the choices
CDC made about how to best estimate the number of deaths, years of
potential life lost, productivity losses, and medical expenditures
attributable to cigarette smoking; and CDC's attempts to deal with the
limitations inherent in analyses of this kind. We examined CDC's
choices in the context of the alternatives available and determined
whether the alternatives would have resulted in more reasonable
estimates. In reviewing CDC's approach and the available alternatives,
we searched the scientific literature using the electronic databases
MEDLINE and EconLit and reviewed over 200 studies on the consequences
of tobacco and approaches to estimating them. In addition, we reviewed
CDC's documentation of its methods and interviewed CDC officials
involved in the report about their approach and their rationale for
choices made in deriving these estimates. We conducted our work from
December 2002 through July 2003 in accordance with generally accepted
government auditing standards.
In summary, CDC's estimates of the average number of deaths and years
of potential life lost each year due to cigarette smoking were
reasonable. The estimates were based on the increases in deaths from 23
causes that were linked to cigarette smoking. The linkages of cigarette
smoking to increased mortality due to the included causes, such as lung
cancer or cardiovascular disease, had been well established by the
Surgeon General. CDC used the method generally accepted among
epidemiologists for estimating the increased deaths attributable to
cigarette smoking. The data sources CDC used were the best available
and included: the largest study of smoking behavior and health status
available for data on the risk of death in smokers relative to
nonsmokers; the National Health Interview Survey (NHIS) of over 97,000
persons for data on the prevalence of smoking; and death certificates
compiled from all states for mortality data. CDC recognized and handled
appropriately the limitations in the data from these sources.
CDC's estimates of the annual mortality-related productivity losses and
medical expenditures due to cigarette smoking also were reasonable. CDC
estimated productivity losses associated with the years of potential
life lost using assumptions about employment and earnings that are
generally accepted among economists, well-established methods for
extrapolating from present earnings to earnings that would be made in
the future, and large federal data sources on earnings. The assumptions
that CDC made and the methods it used to estimate medical expenditures
were also generally accepted among health care economists. CDC relied
on the most comprehensive data available on medical expenditures, the
federally sponsored National Medical Expenditure Survey (NMES) of over
38,000 persons. For both productivity losses and medical expenditures,
CDC recognized and handled appropriately the limitations in the data.
In its comments on a draft of this report, CDC said that this report,
in general, accurately represents the intent, methods, and decision-
making processes of its April 2002 report.
Background:
The Surgeon General's first report on smoking and health was published
in 1964. This report was the first of many to describe the links
between tobacco smoking and health. Since then, several federal
agencies have issued reports on tobacco and health.[Footnote 2] In the
last four decades, the Office of the Surgeon General has published
dozens of reports on the health consequences of smoking. CDC's Office
on Smoking and Health originated as the National Clearinghouse for
Smoking and Health in the Office of the Surgeon General and became part
of CDC in 1986. Through this office, CDC has become a chief source of
information on the health consequences of smoking.
Although the health consequences of cigarette smoking are numerous,
CDC's April 2002 report provided four estimates--number of deaths,
years of potential life lost, mortality-related productivity losses,
and annual medical expenditures attributable to cigarette smoking. The
estimate of number of deaths is the foundation for both the years of
potential life lost and mortality-related productivity loss estimates.
Number of deaths and years lost are two different ways of measuring
mortality attributable to cigarette smoking, and mortality-related
productivity loss is a way of measuring lives and years of life lost in
economic terms. All three of these estimates are limited to mortality
and do not measure morbidity attributable to cigarette smoking, such as
disability, diminished quality of life, and reduced productivity
associated with diseases linked to cigarette smoking. Unlike the other
three estimates, CDC's estimate of annual medical expenditures
attributable to cigarette smoking includes the additional medical
expenses attributable to cigarette smoking of all smokers in a given
year, not those who died in that year. Thus, CDC's estimate is of
annual medical expenditures for morbidity attributable to cigarette
smoking. CDC labels as economic costs attributable to cigarette smoking
the sum of its estimates of mortality-related productivity losses and
medical expenditures. However, this summary estimate of economic costs
does not include such costs as time lost in the workplace due to sick
leave and disability.
CDC's Estimates of Number of Deaths and Years of Potential Life Lost
Due to Cigarette Smoking Were Reasonable:
CDC's estimates of an average of over 440,000 premature deaths and 5.6
million years of potential life lost each year attributable to
cigarette smoking were reasonable. CDC relied on well-established
criteria for the causes of death to include and used the standard
method for attributing deaths to cigarette smoking. In addition, it
used the best data sources available and recognized and handled
appropriately the limitations in the data on which the estimates are
based.
Total Number of Deaths Attributable to Cigarette Smoking:
CDC's estimate of the average total number of deaths attributable to
cigarette smoking annually is the sum of deaths in four categories that
reflect differences in how the estimates are obtained: adult deaths
from diseases causally linked to cigarette smoking, infant deaths from
conditions causally linked to maternal cigarette smoking during
pregnancy, adult deaths from diseases causally linked to exposure to
secondhand cigarette smoke, and deaths from residential fires caused by
smoking. (See table 1.) CDC generated the estimates of adult deaths
from diseases linked to cigarette smoking and infant deaths from
conditions linked to maternal cigarette smoking and relied on the
estimates of others for secondhand smoke and fire deaths.
Table 1: CDC's Estimates of Average Annual Deaths Attributable to
Cigarette Smoking and Years of Potential Life Lost (1995 to 1999):
Adult deaths from diseases causally linked to cigarette smoking[A]:
Cancer of lip, oral cavity, pharynx; Deaths: 5,137; Percentage of
total deaths: 1.2; Years of potential life lost (YPLL): 85,521;
Percentage of total YPLL: 1.5.
Cancer of esophagus; Deaths: 7,893; Percentage of total deaths: 1.8;
Years of potential life lost (YPLL): 120,045; Percentage of total
YPLL: 2.1.
Cancer of pancreas; Deaths: 6,480; Percentage of total deaths: 1.5;
Years of potential life lost (YPLL): 98,593; Percentage of total
YPLL: 1.8.
Cancer of larynx; Deaths: 3,127; Percentage of total deaths: 0.7;
Years of potential life lost (YPLL): 48,616; Percentage of total YPLL:
0.9.
Cancer of trachea, lung, bronchus; Deaths: 124,813; Percentage of
total deaths: 28.2; Years of potential life lost (YPLL): 1,869,786;
Percentage of total YPLL: 33.3.
Cancer of cervix uteri; Deaths: 522; Percentage of total deaths: 0.1;
Years of potential life lost (YPLL): 13,606; Percentage of total
YPLL: 0.2.
Cancer of urinary bladder; Deaths: 4,752; Percentage of total deaths:
1.1; Years of potential life lost (YPLL): 53,498; Percentage of total
YPLL: 1.0.
Cancer of kidney, other urinary; Deaths: 3,035; Percentage of total
deaths: 0.7; Years of potential life lost (YPLL): 46,039; Percentage
of total YPLL: 0.8.
Hypertension; Deaths: 6,060; Percentage of total deaths: 1.4; Years of
potential life lost (YPLL): 87,577; Percentage of total YPLL: 1.6.
Ischemic heart disease; Deaths: 81,976; Percentage of total deaths:
18.5; Years of potential life lost (YPLL): 1,172,699; Percentage of
total YPLL: 20.9.
Other heart diseases; Deaths: 29,368; Percentage of total deaths:
6.6; Years of potential life lost (YPLL): 371,083; Percentage of total
YPLL: 6.6.
Cerebrovascular disease; Deaths: 17,445; Percentage of total deaths:
3.9; Years of potential life lost (YPLL): 280,728; Percentage of total
YPLL: 5.0.
Atherosclerosis; Deaths: 2,527; Percentage of total deaths: 0.6; Years
of potential life lost (YPLL): 22,802; Percentage of total YPLL: 0.4.
Aortic aneurysm; Deaths: 9,624; Percentage of total deaths: 2.2; Years
of potential life lost (YPLL): 116,223; Percentage of total YPLL: 2.1.
Other arterial disease; Deaths: 1,605; Percentage of total deaths:
0.4; Years of potential life lost (YPLL): 20,894; Percentage of total
YPLL: 0.4.
Pneumonia, influenza; Deaths: 15,576; Percentage of total deaths:
3.5; Years of potential life lost (YPLL): 156,133; Percentage of total
YPLL: 2.8.
Bronchitis, emphysema; Deaths: 17,696; Percentage of total deaths:
4.0; Years of potential life lost (YPLL): 216,376; Percentage of total
YPLL: 3.9.
Chronic airways obstruction; Deaths: 64,735; Percentage of total
deaths: 14.6; Years of potential life lost (YPLL): 732,189; Percentage
of total YPLL: 13.0.
Adult smoker deaths from disease; Deaths: 402,373; Percentage of total
deaths: 91.0; Years of potential life lost (YPLL): 5,512,405;
Percentage of total YPLL: 98.1.
Infant deaths from conditions causally linked to maternal cigarette
smoking during pregnancy[B]:
Short gestation/low birthweight; Deaths: 402; Percentage of total
deaths: 0.09; Years of potential life lost (YPLL): 30,556;
Percentage of total YPLL: 0.54.
Respiratory distress syndrome; Deaths: 109; Percentage of total
deaths: 0.02; Years of potential life lost (YPLL): 8,198; Percentage
of total YPLL: 0.15.
Other respiratory--newborn; Deaths: 117; Percentage of total deaths:
0.03; Years of potential life lost (YPLL): 8,793; Percentage of total
YPLL: 0.16.
Sudden infant death syndrome; Deaths: 377; Percentage of total
deaths: 0.09; Years of potential life lost (YPLL): 28,677;
Percentage of total YPLL: 0.51.
Infant deaths from maternal smoking; Deaths: 1,007; Percentage of
total deaths: 0.23; Years of potential life lost (YPLL): 76,224;
Percentage of total YPLL: 1.36.
Lung cancer; Deaths: 3,000; Percentage of total deaths: 0.7; Years of
potential life lost (YPLL): -; Percentage of total YPLL: -.
Ischemic heart disease; Deaths: 35,053; Percentage of total deaths:
7.9; Years of potential life lost (YPLL): -; Percentage of total YPLL:
-.
Adult deaths from secondhand smoke; Deaths: 38,053; Percentage of
total deaths: 8.6; Years of potential life lost (YPLL): -; Percentage
of total YPLL: -.
Deaths from residential fires caused by smoking; Deaths: 966;
Percentage of total deaths: 0.2; Years of potential life lost (YPLL):
27,756; Percentage of total YPLL: 0.5.
Total deaths attributable to cigarette smoking; Deaths: 442,398;
Percentage of total deaths: 100.0; Years of potential life lost (YPLL):
5,616,385; Percentage of total YPLL: 100.0.
Source: CDC, "Annual Smoking-Attributable Mortality, Years of Potential
Life Lost, and Economic Costs - United States, 1995-1999.":
Note: Individual entries may not sum to totals because of rounding.
[A] For adults 35 years old and older.
[B] For infants 1 year old and younger.
[End of table]
In deciding which causes of death to include in its analysis, CDC
relied on the Surgeon General's determination of the causes of death
linked to cigarette smoking.[Footnote 3] These determinations are based
on extensive reviews of scientific literature and are widely regarded
as valid. When new data become available, the Surgeon General's
determination changes accordingly. An alternative method of estimating
deaths attributable to cigarette smoking that does not depend on
decisions about which causes of death to include has been employed by
some researchers. Rather than including only those deaths due to
diseases or conditions that the Surgeon General considers linked to
cigarette smoking, this method estimates deaths attributable to
cigarette smoking regardless of the specific cause of death. CDC
officials told us that they explored this approach, which yielded an
estimate of over 540,000 deaths attributable to cigarette smoking
during 1999, but chose not to use it because it would have resulted in
inflated estimates.[Footnote 4]
The method that CDC used to estimate adult and infant deaths and that
others used to estimate secondhand smoke deaths is generally accepted
among epidemiologists as appropriate for attributing deaths to
cigarette smoking.[Footnote 5] Use of this method is necessary because
it is not possible to definitively attribute an individual case of
disease to smoking--deaths from a disease can only be attributed to
smoking on a population basis.[Footnote 6] For example, in the case of
lung cancer, not all cigarette smokers develop lung cancer, and not all
people who develop lung cancer are cigarette smokers. Thus, counting
the lung cancer deaths in cigarette smokers and attributing them to
cigarette smoking would not be accurate because some of those deaths
would have occurred even in the absence of cigarette smoking. Instead,
the generally accepted approach attributes to cigarette smoking only
the lung cancer deaths among:
smokers that are in excess of those expected among nonsmokers.
Estimates of deaths attributable to cigarette smoking using this
approach are based on three components: (1) estimates of the risk for
smokers[Footnote 7] relative to nonsmokers of dying from each specific
disease or condition linked to cigarette smoking, (2) estimates of the
prevalence of cigarette smoking, and (3) the number of deaths from each
disease and condition. The estimate of deaths attributable to cigarette
smoking derived from these three components for lung cancer, for
example, represents the excess number of lung cancer deaths that
occurred because of cigarette smoking.
Adult Deaths from Diseases Causally Linked to Cigarette Smoking:
CDC's estimate of deaths in adult smokers due to diseases causally
linked to cigarette smoking accounted for about 91 percent of its
estimate of total deaths attributable to cigarette smoking. The data
sources that CDC used for each of the three components of the estimate
of the number of deaths attributable to cigarette smoking all had
limitations that potentially could have affected the estimate. However,
each was the best data source available for each particular purpose,
and CDC recognized and dealt appropriately with the limitations so that
their effects on the estimate were minimal.
For the first component of its estimate of adult deaths--estimating the
risk of death for smokers relative to nonsmokers--CDC used the American
Cancer Society's second Cancer Prevention Study (CPS-II).[Footnote 8]
This study gathered data on individuals' demographic traits, medical
history, and behavior (such as alcohol use) and reported on the
relationship between cigarette smoking and death. CPS-II, with a sample
of about 1.2 million individuals, had a size advantage over other
studies that have similar information. Smaller samples are not
sufficient to produce estimates of cigarette smoking risks that have
margins of error as small as those obtained using CPS-II.
Although the CPS-II sample was not representative of the national
population--for example, nonwhites were underrepresented--adjustments
can be made for the nonrepresentativeness of the overall sample by
estimating cigarette smoking risks taking account of other factors,
such as race. The size of the CPS-II sample enabled CDC to isolate the
increase in risk that was directly attributable to cigarette smoking
and adjust for the effect that multiple factors can have on a person's
risk of death.
For example, although the proportion of nonwhites in the sample was
less than the proportion in the general population, the sample still
contained enough nonwhites to analyze the effect of race on the
relative risks. CDC used data from CPS-II and additional studies to
evaluate the importance of race and other factors--such as education,
alcohol use, and diabetes--and concluded that only age and sex needed
to be taken into account in estimating the relative risks.[Footnote 9]
CPS-II was almost 20 years old at the time of CDC's report. It was
initiated in 1982 and follow-up of individuals in the study is ongoing.
The relative risk estimates that CDC used were based on follow-up
through 1988. Thus, if relative risks had changed over time, those
estimated from CPS-II might not have been accurate for estimating
deaths during 1995 through 1999. However, CDC and others reviewed
studies at different points in time and determined that the relative
risks were likely to have remained stable and were still applicable.
For the second component of the estimate of deaths attributable to
cigarette smoking--estimates of the prevalence of cigarette smoking
among adults--CDC used the National Health Interview Survey (NHIS),
which has detailed data on cigarette smoking for the years included in
CDC's analysis.[Footnote 10] CDC chose to use data that capture
cigarette smoking prevalence during the same years that the deaths of
interest occurred. Using prevalence data from the same years that the
deaths occurred underestimates the number of deaths attributable to
cigarette smoking because, for example, deaths in 1999 are the result
of exposure to cigarette smoke during previous decades and the
prevalence of cigarette smoking declined by 25 percent during the
1990s. In addition, former smokers in 1999 may have been different from
former smokers in the year that relative risks were estimated--that is,
having quit relatively recently, their risk may resemble that of
current smokers more closely than that of former smokers. CDC officials
said that they accepted this limitation since its result was a lower
estimate of the number of deaths attributable to cigarette smoking.
CDC's source for the data needed for the last component of the estimate
of deaths attributable to cigarette smoking--the total number of deaths
due to each disease each year--was death certificates. CDC obtained
these data from the National Center for Health Statistics (NCHS), which
is the national repository for information from birth and death
certificates. NCHS has determined that death certificates accurately
capture the cause of death about 97 percent of the time.
Infant Deaths from Conditions Causally Linked to Maternal Cigarette
Smoking during Pregnancy:
Infant deaths from conditions causally linked to maternal cigarette
smoking accounted for less than one half of 1 percent of the total
deaths attributable to cigarette smoking.CDC's estimate of infant
deaths was based on the same three components as for adults, but the
data sources were necessarily different because, for example, CPS-II
was a study of only adults. CDC's source of data for the first
component--estimates of the risk of dying for infants whose mothers
smoked cigarettes during pregnancy relative to those whose mothers did
not smoke--was a review of studies of the effects of maternal cigarette
smoking.[Footnote 11] For the second component, CDC used data compiled
from birth certificates and surveys of new mothers to obtain estimates
of cigarette smoking prevalence among pregnant women. As for adult
deaths, the source for the last component of the estimate was NCHS data
on the number of infant deaths each year from each condition.
Adult Deaths from Diseases Causally Linked to Exposure to Secondhand
Cigarette Smoke:
Deaths associated with secondhand cigarette smoke accounted for about 9
percent of CDC's estimated total number of deaths attributable to
cigarette smoking. CDC obtained its estimates of deaths attributable to
secondhand cigarette smoke from a National Cancer Institute (NCI)
report.[Footnote 12] CDC used the NCI report's estimate of 3,000 annual
lung cancer deaths associated with secondhand cigarette smoke.[Footnote
13] The NCI report presented a range of estimates (35,000-62,000) for
deaths from ischemic heart:
disease. CDC used the estimate of 35,000 because it was the lowest of
the range and relied on the same data source CDC used to develop
estimates for adult deaths due to cigarette smoking (CPS-II) and thus
would be consistent with those estimates.
Deaths from Residential Fires Caused by Smoking:
Deaths from residential fires accounted for less than one half of 1
percent of CDC's estimated total number of deaths attributable to
cigarette smoking.[Footnote 14] CDC obtained its estimates of
residential fire deaths from the National Fire Protection Association
(NFPA). NFPA national estimates are of the average annual number of
deaths due to fires caused by smoking and are based on data reported to
the U.S. Fire Administration and NFPA's annual survey of fire
departments.[Footnote 15]
Years of Potential Life Lost:
CDC's estimate of the years of potential life lost was built on the
estimate of number of deaths attributable to cigarette smoking and
provided another perspective on mortality attributable to cigarette
smoking. CDC reported that, on average, men and women who died from
cigarette smoking-related illness each lost about 13 and 15 years of
life, respectively. When mortality attributable to cigarette smoking is
measured in terms of the number of deaths, each death contributes
equally to the total. In contrast, when mortality is measured in terms
of years of potential life lost, each death contributes to the total
depending on how premature the death was. This measure takes life
expectancy into account, and thus death at a younger age results in a
greater loss of potential years of life than death at an older age. For
example, an infant who died as a result of maternal cigarette smoking
would likely have had a greater life expectancy than an elderly
lifetime smoker who died of lung cancer and so would contribute more
years of potential life lost to the total. Thus, although infant
mortality accounts for .23 percent of the total number of deaths, it
accounts for almost six times that percentage (1.36 percent) of the
total number of years lost. In contrast, adult lung cancer mortality
accounts for about the same proportion of both the total number of
deaths and the total number of years lost.
CDC used national life expectancy data published by NCHS to estimate
the expected years of life remaining for those who died from cigarette
smoking. The expected life:
span differs for women and men, by age group, and by year
assessed.[Footnote 16] For example,
in 1995, a 65-year old woman was expected to live another 19 years to
age 84 and a 65-year old man was expected to live another 16 years to
age 81. A 75-year old woman in that year was expected to live another
12 years to age 87. In contrast to life expectancies in 1995, a 65-year
old woman in 1950 had an expected life span of 80 years. CDC calculated
years of potential life lost by multiplying the estimated remaining
life expectancy for each sex and age group in each year from 1995
through 1999 by the number of cigarette smoking-attributable deaths in
that group in each year.[Footnote 17] CDC did not estimate the years
lost from secondhand cigarette smoke deaths because the NCI report from
which CDC obtained the estimate of secondhand smoke deaths did not have
sufficient age-specific data. Thus CDC's estimate of the total number
of potential years of life lost did not include the lost years
associated with about 9 percent of the total estimated deaths.
:
CDC's Estimates of Mortality-Related Productivity Losses and Medical
Expenditures Due to Cigarette Smoking Were Reasonable:
CDC's estimates of $82 billion annually in productivity losses from
mortality attributable to cigarette smoking and $76 billion in
additional medical expenditures for all smokers annually were
reasonable. CDC arrived at these estimates using approaches that were
generally accepted among economists and relied on large federal data
sources. CDC recognized and handled appropriately the limitations in
the data on which the estimates are based.
Mortality-Related Productivity Losses:
CDC's estimate of mortality-related productivity losses built on its
estimates of death and years of potential life lost and measured
mortality in economic terms. CDC valued the years of potential life
lost in terms of the productivity lost as a result of those lost years.
CDC used expected future earnings, calculated in current dollars, to
represent mortality-related productivity losses. An alternative
approach to estimating mortality-related productivity losses attempts
to capture the broader impact on productivity of death by accounting
for such factors as time and costs to replace workers and restore
productivity levels.[Footnote 18] CDC did not take this approach
because it was not widely accepted.
In estimating mortality-related productivity losses, CDC used estimates
of expected earnings[Footnote 19] derived from the Bureau of Labor
Statistics (BLS), U.S. Census Bureau, and other national sources. They
take into account both changes in earnings and the value of money over
time. They also include the estimated value of household work that
accounts for the productivity losses among individuals who do not earn
wages for household services. CDC updated the published earnings
estimates using an adjustment factor from BLS so that the estimates
would reflect 1995-99 earnings. CDC used a single average estimate of
future lifetime earnings for men and women. Because of men's higher
average earnings and higher incidence of cigarette smoking-related
death compared to women, the productivity loss estimate was likely to
be lower than if separate average earnings had been used for men and
women.
CDC's estimate of mortality-related productivity losses did not include
the expected lost earnings associated with infant or secondhand
cigarette smoke deaths (about 9 percent of the total deaths). CDC said
that it did not develop an estimate of productivity losses for infants
because of a lack of consensus among economists about the best method
for estimating the potential future earnings of infants. Similarly, the
NCI report from which CDC obtained the estimate of secondhand smoke
deaths lacked specific data on the age at which those deaths occurred-
-information needed to estimate expected lost earnings. CDC informed us
that it is working on including these two categories in future
estimates of productivity losses when more reliable data become
available.
Medical Expenditures:
CDC's estimate of $76 billion annually in additional medical
expenditures attributable to cigarette smokers was not built on the
other three estimates, and its approach to developing this estimate was
different from its approach to the others. CDC examined the use of
health care services and the cost of those services for smokers
compared to nonsmokers independent of the reason--that is, the disease
or condition--for the services. Thus, this estimate is not limited to
medical expenditures associated with a set of diseases and conditions
causally linked to cigarette smoking. CDC's estimate of total medical
expenditures was the sum of five estimates by type of health care
service for adults--ambulatory care, hospital care, prescription drugs,
nursing home,[Footnote 20] and other (including home health care,
nonprescription drugs, and nondurable medical equipment)--and an
estimate of expenditures for neonatal health care services. (See table
2.) CDC estimated these expenditures on an annual basis.
Table 2: CDC's Estimates of Annual Mortality-Related Productivity
Losses and Medical Expenditures Attributable to Cigarette Smoking:
Dollars in millions.
Mortality-related productivity losses:
Men; $55,389.
Women; 26,483.
Total mortality-related productivity losses; $81,872.
Medical expenditures[A]:
Ambulatory care; $27,182.
Hospital care; 17,140.
Prescription drugs; 6,364.
Nursing home; 19,383.
Other care; 5,419.
Neonatal; 366.
Total medical expenditures; $75,854.
Source: CDC, "Annual Smoking-Attributable Mortality, Years of Potential
Life Lost, and Economic Costs - United States, 1995-1999.":
[A] CDC's estimate of annual personal medical expenditures for adults
attributable to cigarette smoking was derived using 1998 data obtained
from the Health Care Financing Administration and is in 1998 dollars.
Its estimate of annual neonatal medical expenditures attributable to
maternal cigarette smoking was based on 1996 data and is in 1996
dollars.
[End of table]
The data source that CDC used to determine medical expenditures for
smokers compared to nonsmokers allowed CDC to adjust for many factors-
-including certain risk-taking behaviors (e.g., not wearing a seat
belt)--that may affect health care expenditures independent of smoking
status.[Footnote 21] However, although the data source was the most
comprehensive available, it did not include information on alcohol
consumption. CDC used data from another study to assess the importance
of drinking alcohol with respect to expenditures attributable to
cigarette smoking and concluded that adjusting the data for drinking
would not have had an appreciable effect on the results.[Footnote 22]
Expenditures for dental care and mental health care and certain costs
associated with the care of infants of cigarette smoking mothers were
not included in CDC's estimate.[Footnote 23] In addition, certain
expenditures for health services associated with secondhand cigarette
smoke (e.g., care for lung cancer due to secondhand cigarette smoke in
a nonsmoker) and care for nonsmokers injured in residential fires
caused by smoking are not accounted for in the estimate.
By estimating medical expenditures on an annual basis, CDC avoided
limitations associated with the alternative of estimating expenditures
over an individual's lifetime. The lifetime approach is based on a
series of assumptions and predictions about disease course and
duration, survival rates, patterns of medical care, and impact of
disease on employment, among other factors. Results using a lifetime
approach have varied widely--some studies have concluded that smokers
have more medical expenditures than nonsmokers over their lifetimes and
other studies have come to the opposite conclusion.[Footnote 24]
Changes in the assumptions underlying the annual approach have less of
an effect on the results. CDC's estimates are consistent with other
annual estimates of medical expenditures published in the
literature.[Footnote 25]
Agency Comments:
In its comments on a draft of this report (see enclosure III), CDC said
that this report, in general, accurately represents the intent,
methods, and decision-making processes of its April 2002 report. With
respect to our discussion of the relative risks obtained from CPS-II,
CDC noted that while the overall prevalence of smoking may have
decreased since CPS-II, the relative risks for smokers compared to
nonsmokers would not have decreased because smoking behavior was
similar. We have incorporated CDC's technical comments as appropriate.
As agreed with your office, unless you publicly announce its contents
earlier, we plan no further distribution of this report until 30 days
after its issue date. At that time, we will send copies to the Director
of CDC and other interested parties. We will also make copies available
to others upon request. In addition, this report will be available at
no charge on GAO's Web site at http://www.gao.gov. If you have
questions or would like additional information, please call me at (202)
512-7119. Another contact and contributors to this report are listed in
enclosure IV.
Sincerely yours,
Janet Heinrich:
Director, Health Care--Public Health Issues:
Signed by Janet Heinrich:
Enclosures:
CDC's Table Presenting Its Estimates of Cigarette Smoking-
Attributable Mortality and Years of Potential Life Lost:
[See PDF for image]
Note: This table is taken from page 302 of CDC, "Annual Smoking-
Attributable Mortality, Years of Potential Life Lost, and Economic
Costs - United States, 1995-1999.":
[End of table]
CDC's Table Presenting Its Estimates of Smoking-Attributable
Mortality-Related Productivity Losses and Medical Expenditures:
[See PDF for image]
Note: This table is taken from page 303 of CDC, "Annual Smoking-
Attributable Mortality, Years of Potential Life Lost, and Economic
Costs - United States, 1995-1999.":
[End of table]
Comments from the Centers for Disease Control and Prevention:
DEPARTMENT OF HEALTH & HUMAN SERVICES Public Health Service:
Centers for Disease Control and Prevention (CDC) Atlanta GA 30333:
JUL 11 2003:
Ms. Janet Heinrich Director:
Health Care - Public Health Issues U.S. General Accounting Office:
441 G Street, N.W., Mail Drop 5AI4 Washington, D.C. 20548:
Dear Ms. Heinrich:
The Centers for Disease Control and Prevention (CDC) appreciates the
opportunity to review and comment on the U.S. General Accounting
Office's (GAO) proposed correspondence entitled CDC's APRIL 2002 REPORT
ON SMOKING: Estimates of Selected Health Consequences of Cigarette
Smoking Were Reasonable (GAO-03-942R).
CDC commends GAO for this well-written report which, in general,
accurately represents the intent, methods, and decision-making
processes of the April 2002 Morbidity and Mortality Weekly Report
(MMWR) article on the disease burden of smoking.
Enclosed are CDC's general and technical comments. If you or your staff
should have any questions regarding these comments, please contact Ms.
Jenelda Thomton of CDC's National Center for Chronic Disease Prevention
and Health Promotion. Ms. Thornton may be reached by telephone at 770-
488-6417 or by email at JThornton@cdc.gov.
Sincerely,
Julie Louise Gerberding, M.D., M.P.H.
Director:
Signed by Julie Louise Gerberding:
GAO Contact and Staff Acknowledgments:
GAO Contact:
Michele Orza, (202) 512-6970:
Acknowledgments:
The following staff members made important contributions to this work:
Angela Choy, Chad Davenport, Maria Hewitt, Donald Keller, and Nkeruka
Okonmah.
(290254):
FOOTNOTES
[1] Centers for Disease Control and Prevention (CDC), "Annual Smoking-
Attributable Mortality, Years of Potential Life Lost, and Economic
Costs - United States, 1995-1999," Morbidity and Mortality Weekly
Report, vol. 51, no. 14 (2002): 300-303. Morbidity and Mortality Weekly
Report is a CDC publication for dissemination of information about the
public health issues in which CDC is involved.
[2] See for example, U.S. Department of Health, Education, and Welfare,
National Institutes of Health, National Cancer Institute, and National
Heart, Lung, and Blood Institute, Smoking and Health: A Program to
Reduce the Risk of Diseases in Smokers, Status Report (Bethesda, Md.:
December 1978); U.S. Department of Agriculture, Economic Research
Service, Tobacco: Situation and Outlook (Washington, D.C.: April 1995);
U.S. Department of the Treasury, The Economic Costs of Smoking in the
U.S. and the Benefits of Comprehensive Tobacco Legislation (Washington,
D.C.: March 1998); and U.S. Department of Health and Human Services,
National Institutes of Health, National Cancer Institute, Strategies to
Control Tobacco Use In the United States: A Blueprint for Public Health
Action In the 1990's, Smoking and Tobacco Control Monograph 1
(Bethesda, Md.: December 1991).
[3] The Surgeon General's determinations are based on the application
of standard criteria for establishing causality to information from
comprehensive reviews of the scientific literature. For standard
causality criteria, see A. B. Hill, "The Environment and Disease:
Association or Causation?" Proceedings of the Royal Society of
Medicine, vol. 58, no. 5 (1965): 295-300.
[4] This method was also applied to 1993 data and produced an estimate
of 569,000 deaths attributable to cigarette smoking in 1993. D.M.
Burns, L. Garfinkel, and J.M. Samet, "Introduction, Summary, and
Conclusions," Changes in Cigarette-Related Disease Risks and Their
Implication for Prevention and Control, Smoking and Tobacco Control
Monograph 8 (Bethesda, Md.: U.S. Department of Health and Human
Services, 1997).
[5] See, for example, P. Bruzzi et al., "Estimating the Population
Attributable Risk for Multiple Risk Factors Using Case-control Data,"
American Journal of Epidemiology, vol. 122, no. 5 (1985): 904-914.
[6] It was not necessary to use this method to estimate deaths from
fires because, unlike deaths from disease, an individual death in a
fire can be definitively attributed to smoking if the fire department
determines that smoking was the cause of the fire.
[7] Smokers are generally classified as either current smokers or
former smokers, and separate estimates are derived for each group.
[8] M.J. Thun et al., "Trends in Tobacco Smoking and Mortality from
Cigarette Use in Cancer Prevention Studies I (1959 through 1965) and II
(1982 through 1988)," Changes in Cigarette-Related Disease Risks and
Their Implication for Prevention and Control, Smoking and Tobacco
Control Monograph 8 (Bethesda, Md.: U.S. Department of Health and Human
Services, 1997). Study participants self-reported information on their
medical history, current health status, and a series of lifestyle
factors including smoking behaviors. During the 6-year follow-up
period, deaths among participants were recorded along with the cause of
death as recorded on the death certificate. Death certificates were
obtained for approximately 97 percent of all study participants known
to have died.
[9] M.J. Thun, L.F. Apicella, and S.J. Henley, "Smoking vs Other Risk
Factors as the Cause of Smoking-Attributable Deaths: Confounding in the
Courtroom," JAMA, vol. 284, no. 6 (2000): 706-712 and A.M. Malarcher et
al., "Methodological Issues in Estimating Smoking-Attributable
Mortality in the United States," American Journal of Epidemiology, vol.
152, no. 6 (2000): 573-584.
[10] The National Health Interview Survey (NHIS) is a nationally
representative survey of health trends in the civilian population. The
survey collects basic health and demographic information every year and
frequently includes questions on smoking. The 1999 NHIS sample
consisted of 37,573 households, which yielded 97,059 persons in 38,171
families. For the adult component, 30,801 persons 18 years or older
were interviewed.
[11] N.I. Gavin, C. Wiesen, and C. Layton, Review and Meta-Analysis of
the Evidence on the Impact of Smoking on Perinatal Conditions Built
into SAMMEC II, (Washington, D.C.: Centers for Disease Control and
Prevention, September 2000).
[12] U.S. Department of Health and Human Services, National Institutes
of Health, National Cancer Institute, Health Effects of Exposure to
Environmental Tobacco Smoke: The Report of the California Environmental
Protection Agency, Smoking and Tobacco Control Monograph 10 (Bethesda,
Md.: 1999).
[13] The NCI report cited the Environmental Protection Agency's (EPA)
estimate of 3,000 annual lung cancer deaths associated with secondhand
smoke (see U.S. Environmental Protection Agency, Office of Research and
Development, Office of Health and Environmental Assessment, Respiratory
Health Effects of Passive Smoking: Lung Cancer and Other Disorders
(Washington, D.C.: December 1992)). After the report was published,
several tobacco companies filed a lawsuit seeking to have the report
withdrawn, claiming that EPA had violated procedural requirements in
developing the report. In 1998, a district court invalidated certain
chapters of the report, including those on lung cancer. In December
2002, the U.S. Court of Appeals overturned the district court's
decision and ordered that the suit be dismissed, concluding that the
district court had lacked jurisdiction to hear the suit. (See Flue-
Cured Tobacco Cooperative Stabilization Corporation v. United States
EPA, 313 F.3d 852 (4th Cir. 2002).)
[14] The National Fire Protection Association (NFPA) estimate that CDC
cited includes deaths from the 1 to 2 percent of fires caused by cigars
and pipes. The estimate does not include deaths from nonresidential and
auto-related fires.
[15] The United States Fire Association (USFA) is part of the Federal
Emergency Management Agency. The fire reports sent to USFA's voluntary
fire reporting system account for about half of the fires each year,
and representation of certain regions of the country and communities
may not be uniform. To address these issues, NFPA supplements USFA's
data with its own annual survey of a sample of fire departments. NFPA
assumes that fires with unknown or unreported causes have the same
proportional distribution as fires for which the cause is known and
reported.
[16] Life expectancy also differs by race, with blacks of both sexes
and of all ages generally having lower life expectancies than whites
for all years. CDC did not estimate cigarette-smoking attributable
deaths separately by race and thus did not estimate years of potential
life lost by race.
[17] An alternative method for estimating years of potential life lost
is to calculate the years of life remaining using life expectancy at
birth rather than at the age of death. This method would likely have
resulted in a lower estimate of the total years of productive life
lost; however, it is not the method generally accepted among public
health experts.
[18] M.A. Koopmanschap, "Estimating the Indirect Costs of Smoking Using
the Friction Cost Method," ed. C. Jeanrenaud and N. Soguel, Valuing the
Cost of Smoking: Assessment Methods, Risk Perception and Policy Options
(Boston: Kluwer Academic Publishers, 1999).
[19] CDC's estimates were drawn from A.C. Haddix et al., eds.,
Prevention Effectiveness: A Guide to Decision Analysis and Economic
Evaluation (New York: Oxford University Press, 1996).
[20] CDC's nursing home estimate accounts for differences between
smokers and nonsmokers in the likelihood of admission to a nursing home
but not differences in readmission or length of stay.
[21] CDC's primary data source for determining medical expenditures for
smokers compared to nonsmokers was the 1987 National Medical
Expenditure Survey, a population-based survey of over 38,000
individuals in about 14,000 households.
[22] This study assessed utilization of health care services using data
from a nationally representative survey of adults that included
information on utilization of medical care, smoking, and alcohol
consumption. CDC based its conclusion on findings from this study,
after an expert panel determined that these findings were applicable to
CDC's analysis. V.P. Miller, C. Ernst, and F. Collin, "Smoking-
Attributable Medical Care Costs in the USA," Social Science & Medicine,
vol. 48, no. 3 (1999): 375-391.
[23] CDC's estimate of costs associated with smoking during pregnancy
includes only neonatal hospital expenditures and excludes costs of care
throughout infancy (for example, those associated with hospital
readmissions in the first year of life) and expenditures associated
with treating secondhand smoke-related conditions arising after birth.
The estimates were based on data from CDC's Pregnancy Risk Assessment
Monitoring System and 1996 private sector claims data from the Medstat
MarketScan™ database.
[24] For an example of a study that found greater lifetime expenditures
for smokers, see T.A. Hodgson, "Cigarette Smoking and Lifetime Medical
Expenditures," Milbank Quarterly, vol. 70, no. 1 (1992): 81-125. For an
example of a study that found fewer lifetime expenditures for smokers,
see B.C. Lippiatt, "Measuring Medical Cost and Life Expectancy Impacts
of Changes in Cigarette Sales," Preventive Medicine, vol.19, no. 5
(1990): 515-532.
[25] CDC's estimate of annual personal medical expenditures
attributable to smoking, $76 billion, represents approximately 8
percent of total personal medical expenditures, an estimate within the
range of other annual estimates (from about 6 to about 9 percent). See
W. Max, "The Financial Impact of Smoking on Health-related Costs: A
Review of the Literature," American Journal of Health Promotion, vol.
15, no. 5 (2001): 321-333.