IZ

TABLE 3.—Outline of prospective studies of smoking and overall

mortality

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Doll Dorn Best Weir Cederlof
Hill . : Hammond Dunn Friberg
Authors Hammond Kahn Hirayama Josie i
Peto Rogot Walker Horn Linden Hrubec
Pike e° Breslow Lorich
(410) (14,16-19) (11,26,81,88) (21,28-25) (1,13) (20) (12,38) (2)
Males and Total population ; California Probability
a: females of ; White males : sample of
. British : US. Canadian : males in
Subjects doctors in veterans 29 health in various the
25 districts in pensioners nine States occupations Swedish
States Japan P population
Population size 40,000 1,000,000 290,000 265,000 92,000 187,000 68,000 55,000
Females 6,000 562,671 <1% 142,857 14,000 27,700
Age range 20-85 + 35-84 35-84 and up 30-90 50-69 33-64 18-69
Hear ot 1951 1960 1954 1966 1955 1952 1954 1968
enrollment 1957
Years of
followup 20 years 12 years 18 years 8 years 6 years 4 years 58 10 years
10 years years
reported
Number
of 10,072 150,000 87,000 21,000 11,000 12,000 4,700 4,500
deaths
Person years
of 600,000 8,000,000 3,500,000 2,000,000 500,000 670,000 480,000 550,000
experience

 

 
information on age, sex, race, education, place of residence, family
history, past diseases, present physical complaints, occupational
exposures, and various habits. Information on smoking included: type
of tobacco used, number of cigarettes smoked per day, inhalation, age
started smoking, and the brand of cigarettes used from which tar and
nicotine content of the cigarette could be calculated. Nearly 98 percent
of the survivors were successfully followed for a 12-year period.

The U.S. Veterans Study (26)

This study followed the mortality experience of 250,000 U.S. veterans
who held Government life insurance policies in December of 1958.
Almost all policy holders were white males. This group has been
followed for 16 years. The most recent analysis was limited to overall
mortality, as death certificates were not obtained for those who died
during the last half of the study period. Smoking habits were
determined only once, at the onset of the study.

Japanese Study of 29 Health Districts (24)

In late 1965, a total of 265,118 men and women in 29 health districts in
Japan were enrolled in a prospective study. This represented from 91
to 99 percent of the population aged 40 and older in these districts. This
study provides a unique opportunity to examine the relationship of
cigarette smoking to death rates in a population with genetic, dietary,
and other cultural differences from previously examined Western
populations. At the time of the 8th year of follow-up, 11,858 deaths had
occurred and there were 1,269,882 person-years of observation. The
overall mortality rate for Japanese males who began smoking at a
young age was quite similar to that reported for U.S. males by
Hammond (17). Mortality ratios for most categories, however, are
considerably lower than those reported for the United States, Canada,
and Great Britain. This most likely reflects a lower average number of
cigarettes smoked per day, an older age at initiation of smoking, or
reduced inhalation of cigarette smoke among the Japanese.

In spite of these differences, the overall results of this study,
including the dose-response relationships for the various diseases
caused by smoking, are similar to the results of all the other major
epidemiological studies. The reliability and accuracy of the methods of
population selection used in other studies based on limited samples of
the population are confirmed by this study based on a total population
in a study area.

The Canadian Veterans Study (/)

Beginning in 1955, the Canadian Department of Nationa! Health and
Welfare enrolled 78,000 men and 14,000 women in a study of smoking-
related mortality. Information was obtained on age, detailed smoking

2—14
history, residence, and occupation. During the 6 years of follow-up,
there were 9,491 deaths of males and 1,794 deaths of females. No
recent follow-up has been reported.

The American Cancer Society 9-State Study (20)

In this study, 187,783 white males were followed for an average of 44
months. The study began in early 1952. There were 11,870 deaths in
this population aged 50 to 70. The last significant report on this study
was published in 1958.

California Men in Various Occupations (12)

This study examined the mortality experience of 68,153 men, 35 to 64
years of age, over a period of 482,658 person-years of observation. A
total of 4,706 deaths occurred. These men were in nine occupational
groups. The last published report from this study was in 1970.

The Swedish Study (2)

A probability sample of 55,000 Swedish men and women was surveyed
in 1963. A 10-year follow-up on smoking-related mortality was
published in 1975.

Mortality and Male Cigarette Smokers

Overall mortality rates for male cigarette smokers are significantly
higher than for nonsmoking males. The mortality ratios are as low as
1.25 for Japanese males and as high as 1.83 for the males in the ACS
25-State Study. These results are shown in Table 4. Important evidence
for a causal relationship between smoking and overall mortality is the
demonstration of dose-response relationships. In most epidemiological
studies, dosage has been measured by the number of cigarettes smoked
daily at the time of entry into the study. Other dose variables include
the maximum number of cigarettes smoked per day, age began
smoking, the depth of inhalation, years of smoking, pack-years, tar and
nicotine levels of the brand of cigarettes used, the number of puffs per
cigarette, and the length of the unburned portion of the cigarette, as
Well as combinations of these variables into various dosage scores. All
of these dosage variables have been shown in one study or another to
contribute to the degree of risk involved in smoking. Several of the
dosage variables as related to overall mortality are examined in this

section.
Mortality and Amount Smoked

Mortality ratios for males currently smoking cigarettes only by
amount smoked are presented for the eight major prospective studies
in Table 4. Even males smoking one to nine cigarettes a day have a

2—15
TABLE 4.—Mortality ratios for males currently smoking cigarettes only, by amount smoked

 

 

 

 

Number of Doll Hammond Rogot Hirayama Best Hammond mv nn Cederlof
cigarettes (9) ay (31,83) (25) (18) (20) (38) (2)
per day
British Males in US. Japanese Canadian Males in California Swedish
doctors 25 States veterans pensioners 9 States occupations .
Nonsmokers 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
1-9 1.41(1-15) 1.45 1.25 141 1.34 144 1.2X(1-7)
10-20 1.57(16-25) 1.75 151 1.56 1.70 179 1.40(8-15)
21-39 2.16(>25) 1.90 1.69 1.65(>20) 1.96 2.27 1.80(>16)
40+ 2.20 1.89 2.23 1.83
All smokers 1.63 1.83 1.55 1.25 1.54 1.74 1.78 1.58

 
TABLE 5.—Mortality ratios for male cigarette-only smokers, by
number of cigarettes smoked per day and age. U.S.
veterans 1954 cohort, 16-year followup

 

 

 

 

Number of Age
cigarettes
per day 30-34 35-44 45-54 55-64 65-74
Nonsmokers 1.00 1.00 1.00 1.00 1.00
less than 10 1.94 1.44 1.44 1.20 115
10-20 1.27 1.79 1.64 1.49 1.30
21-39 1.76 2.23 2.10 1.67 1.42
40+ 2.33 2.72 2.13 1.86 1.65
All smokers 152 1.95 1.83 153 1.32

 

SOURCE: Rogot, FE. (31,33).

significant mortality ratio that varies from 1.25 to 1.45. Smokers of
more than two packs of cigarettes a day have an overall mortality ratio
that varies from 1.83 to 2.23.

Mortality at Different Ages

Overall mortality ratios by amount smoked at different ages for
several studies are presented in Tables 5 through 8. There is a decrease
in the mortality ratio with each increase in age for each smoking
category. Mortality ratios are consistently more than 2.00 for heavy
smokers between the ages of 30 to 50. These ratios decrease gradually
with age, but are still about 1.35 for men over 75 years of age. This
decline does not imply a decrease in the effect of cigarette smoking on
health. Overall mortality rates increase dramatically with age in both
smokers and nonsmokers. If one uses another measure of mortality and
looks at the difference in death rates between smokers and nonsmokers
as illustrated in Table 1, it can be seen that the difference in overall
mortality rates increases with age even though the mortality ratio
decreases.

The decreasing mortality ratio with age is probably due to another
factor that should be considered. The population of older males who
smoke two packs of cigarettes per day is probably quite different than
4 younger group of two-pack-a-day smokers.

Mortality by Duration of Smoking

Overall mortality ratios increase with the duration of the smoking
habit. Mortality ratios by number of years smoked from two studies
are presented in Tables 9 and 10. The mortality ratios remain quite
low, only slightly above the rates for nonsmokers for the first 5 to 15
years of the smoking habit, and then increase more rapidly as the years

2—17
TABLE 6.—Mortality ratios for male cigarette-only smokers, by
number of cigarettes smoked per day and age. Males

in 25 States

 

 

 

 

Number of Age
cigarettes
per day 35-44 45-54 55-64 65-74 15-84

Nonsmokers 1.00 1.00 1.00 100 1.00
19 ** 1.84 1.53 1.50 1.36
10-19 1.36 2.26 1.92 1.65 155
20-39 1.91 241 2.05 L71 126
40+ 2.59 2.76 2.26 181 “
All smokers 1.82 2.20 1.86 1.58 1.35

 

SOURCE: Hammond, E.C. (27).

TABLE 7.—Mortality ratios for male cigarette-only smokers, by
number of cigarettes smoked per day and age.
Canadian pensioners

 

 

 

 

Number of Age
cigarettes
per day 30-34 35-44 45-54 55-64 65-74 B+
Nonsmokers 1.00 1.00 1.00 1.00 1.00 1.00
1-9 0.72 1.25 1.07 1.50 1.32 131
10-20 1.22 1.36 1.20 1.94 1.40 133
20+ 1.01 1.35 1.27 2.15 1.45 142
All smokers 0.90 1.63 121 1.89 145 131

 

SOURCE: Doll, R. (9).

TABLE 8.—Mortality ratios for male cigarette-only smokers, by
number of cigarettes smoked per day and age. Males

in nine States

 

 

 

 

Number of Age
cigarettes
per day 50-54 55-59 60-64 65-69
Nonsmokers 1.00 1.00 1.00 1.00
1-9 1.43 1.35 1.46 187
10-20 1.72 1.65 1.83 1.59
21-39 2.11 1.83 2.20 1.65
40+ 2.30 2.84 1.56 184
All smokers 185 1.69 1.84 1.55

 

SOURCE: Hammond, E.C. (20).

of smoking increase. Mortality ratios are as high as 1.66 for male
cigarette smokers who have smoked for 35 or 40 years.

2—18
TABLE 9.—Age-adjusted mortality ratios for male cigarette-only
smokers, by duration of smoking. Canadian veterans

 

 

Duration of Mortality
smoking i
s ratio
in years
Under 5 1.05
5-14 ad
15-29 i
30-39 158
40+ 16
All smokers 152

 

SOURCE: Best, E.W.R. (1)

TABLE 10.—Age-adjusted mortality ratios for male cigarette
smokers who began smoking after the age of 20, by
duration of smoking. U.S. veterans

 

Duration of Mortality
smoking A
: ratio
in years
Under 15 1.10
15-24 1.34
25-34 1.44
35+ 1.66

 

SOURCE: Kahn, H.A. (26).

Mortality by Age Began Smoking

Overall mortality ratios exhibit an inverse relationship with age of
initiation of the smoking habit. Table 11 displays data from the U.S.
Veterans Study. Cigarette-only smokers who began smoking after the
age of 25 have a mortality ratio of 1.32. For individuals who began
smoking under the age of 15, the mortality ratio is 1.86. Data from the
Japanese study are shown in Table 12, Again, a dose-response
relationship is demonstrated but at a lower level than in the United
States. When the Japanese data are broken down further “by age at
start of study” and “age began smoking,” as seen in Table 13, it is
demonstrated that smokers who began smoking under the age of 15
have mortality ratios that are very similar to those in the United
States data. Tables 14 and 15 show overall mortality ratios by “age
began smoking” and “age at beginning of study” for the U.S. veterans

and U.S. males in 25 States.
Overall mortality ratios by “age began smoking” and “number of

cigarettes smoked per day” for the ACS Study of 25 States and the
U.S. Veterans Study are presented in Tables 16 and 17. As expected,

2—19
TABLE 11.—Age-adjusted mortality ratios for male cigarette-only
smokers, by age began smoking. U.S. veterans 1954

 

 

cohort

Age began Mortality

smoking ratio

in years
Nonsmokers 1.00
25+ 1.32
20-24 151
15-19 1.64
Under 15 1.86

 

SOURCE: Rogot, E. (82, 33).

TABLE 12.—Age-adjusted mortality ratios for male cigarette-only
smokers, by age began smoking. Japan

 

Age began

 

. Mortality
smoking ratio
in years

Nonsmokers 1.00
25+ 1.19
20-24 1.19
Under 20 127

 

SOURCE: Hirayama, T. (22).

TABLE 13.—Age-adjusted mortality ratios for Japanese male
cigarette smokers, by age began smoking and age
at start of study

 

 

 

Age began Age at start of study

smoking

in years 40.49 50-59 60-69
Nonsmokers 1.00 1.00 1.00
35+ 1.58 1.08 1.02
30-34 0.89 111 129
2-29 091 Lu 1,19
20-24 0.82 1.16 1.19
15-19 0.92 131 129
Under 15 2.26 3.04 1.86

 

SOURCE: Hirayama, T. (22).

overall mortality ratios increase the younger a person begins smoking
and the greater the number of cigarettes smoked per day.
Mortality by Inhalation of Cigarette Smoke

Inhalation of tobacco smoke is an important dosage variable. Most of
the excess mortality associated with cigarette smoking results from
diseases that require inhalation of smoke well into the lungs in order to

2—20
TABLE 14.—Age-adjusted mortality ratios for male cigarette-only
smokers, by age began smoking and age at start of
study. U.S. veterans 1954 cohort

 

 

 

Age began Age at start of study

smoking

in years 30-34 35-44 45-54 55-64 65-74
Nonsmokers 1.00 1.00 1.00 1.00 1.00
2+ “ 1.48 1.67 1.36 1.20
20-24 141 1.87 172 1.56 139
15-19 1,44 2.00 2.17 1.70 1.45
Under 15 2.00 2.18 2.25 2.02 142

 

SOURCE: Rogot, E. (31, 33).

TABLE 15.—Age-adjusted mortality ratios for male cigarette-only
smokers, by age began smoking and age at start of
study. Males in 25 States

 

 

 

Age began Age at start of study

smoking

in years 45-54 55-64 65-74 15-84
Nonsmokers 1.00 1.00 1.00 1.00
30+ 1.40 1.33 1.23 1.10
25-29 1.81 1.75 1.25 “
20-24 2.13 1.78 1.52 1.27
15-19 2.49 2.11 1.84 1.58
Under 15 3.01 2.26 2.00 1.59

 

SOURCE: Hammond, E.C. (17).

TABLE 16.—Age-adjusted mortality ratios for male cigarette-only
smokers aged 55-64, by age began smoking and
current number of cigarettes smoked per day. Males

 

 

 

in 25 States
Age began Current number of cigarettes per day
smoking
in years Nonsmokers 19 10-19 20-39 40+
B+ 1.00 1.34 1.68 1.48 LIT
1-4 1.00 145 1.89 2.05 2.28
Under 15 1.00 bad 2.15 2.19 2.58

 

SOURCE: Hammond, EC. (17).

expose target organs directly or through absorption of toxic substances
Into the circulatory system. Ischemic heart disease, lung cancer, and
chronic obstructive disease are not as likely to develop in individuals
Who do not inhale smoke. Techniques for quantitating inhalation have
een developed using carboxyhemoglobin as an index of smoke
inhalation, but these methods have not been applied to studies of
overall mortality. Most studies asked the smoker to report subjectively

2—21
TABLE 17.—Age-adjusted mortality ratios for males smoking
cigarettes only, by amount smoked and age began
smoking. U.S. veterans 1954 cohort

 

 

 

Age began Current number of cigarettes
smoking per day
wn years Nonsmokers 1-20 21+
20+ 1.00 1.36 1.59
Under 20 1.00 1.56 182

 

SOURCE: Rogot, E. (31, $3).

on his own inhalation practices. Certainly, self-reporting of inhalation
is subject to considerable variation, but it may not be as inaccurate as
might be presumed. Available data show the expected dose-response
relationship between inhalation of cigarette smoke and overall
mortality. Table 18 demonstrates that with advancing age the
percentage of moderate and deep inhalers drops and the percentage of
none-to-slight inhalers increases. This is consistent with increased
mortality for those who inhale. It also makes the interesting point that
a smoker who survives to old age is different from the younger smoker.
It is likely that the lower mortality ratios experienced by older smokers
are partly a reflection of the fact that they smoke in a less hazardous
fashion than do younger smokers. Older smokers are less likely to
inhale than younger smokers. It is also likely that they take fewer
puffs per cigarette and smoke fewer cigarettes per day. If they have
been faithful to their brand of cigarettes, they are likely to be smoking
an “older” brand. The brand is likely to be unfiltered and more typical
of the cigarettes sold 30 to 40 years ago which contained twice the tar
and nicotine of the average cigarettes sold today. Tables 19, 20, and 21
show age-adjusted mortality ratios by degree of inhalation and number
of cigarettes smoked per day and age at start of study for three of the
large prospective studies. The overall mortality ratio is 2.80 for the
moderate-to-deep inhaler who smokes 40 or more cigarettes per day.
The overall mortality ratio is 2.53 for 45- to 54-year-old men who inhale
deeply, but is 1.02 for noninhalers who are 75 to 84 years old. In the
Canadian study, the highest mortality ratio was 2.11 for those 60 to 69
years old who reported inhaling cigarette smoke. Hammond reported a
mortality ratio of 1.41 for noninhalers who are 45 to 54 years old (15).
This suggests that cigarette smokers may underestimate the extent to
which they inhale cigarette smoke.

Mortality by Tar and Nicotine Content of Cigarettes

Overall mortality increases with the tar and nicotine content of
cigarette smoke. This relationship was recently examined by Ham-
mond, et al. (19). In this study, tar and nicotine levels (T/N) were
defined as follows: “High” T/N, 25.8-35.7 mg tar and 2.0-2.7 mg

2—22
TABLE 18.—Percent distribution of male cigarette smokers by

degree of inhalation of cigarette smoke and age.
Males in 25 States

 

 

 

 

Degree Age
of
inhalation 40-49 50-59 60-69 70-79
None 3.62 6.11 11.46 19.74
Slight 10.97 18.64 20.18 25.56
Moderate 57.94 56.31 51.10 40.82
Deep 27.65 23.91 17.25 18.88
Total 100.00 100.00 100,00 100,00

 

SOURCE: Hammond, E.C. (19).

TABLE 19.—Age-adjusted mortality ratios for male cigarette-only
smokers, by degree of inhalation of cigarette smoke
and current number of cigarettes per day. Subjects
aged 45-54 at start of study. Males in 25 States

 

 

 

Degree Number of cigarettes per day
of
inhalation 19 10-19 20-39 40+
None-slight 1.70 1.99 2.34 2.33
Moderate-deep 1.95 2.35 2.42 2.80

 

SOURCE: Hammond, E.C. (17).

TABLE 20.—Age-adjusted mortality ratios for male cigarette-only
smokers, by degree of inhalation of cigarette smoke
and age at start of study. Males in 25 States

 

 

 

Degree Age at start of study
of
inhalation 45-54 55-64 65-74 75-84
None 141 1.43 132 1.02
Slight 1.67 171 1.31 1.19
Moderate 2.06 1.68 1.53 1.10
Deep 2.58 1.88 1.68 *

eee
SOURCE: Hammond, E.C. (17).

Nicotine; “Medium” T/N, 17.6-25.7 mg tar and 1.2-1.9 mg nicotine;
Low” T/N, less than 17.6 mg tar and less than 1.2 mg nicotine. Table
Shows the overall mortality ratios of male and female smokers by
these tar and nicotine levels. In this instance, the mortality ratio of the
high” T/N smokers is represented as 1.00 so as to illustrate the
reduction in overall mortality that occurs with lower T/N cigarettes.
here is a small but statistically significant (P. less than 0.0005)
reduction in the risk of dying with the use of lower T/N cigarettes. The
Mortality ratio was reduced to 0.91 for the “medium” T/N smokers and

2—23
TABLE 21.—Age-adjusted mortality ratios for male cigarette-only
smokers, by degree of inhalation of cigarette smoke
and age at start of study. Canadian veterans

 

 

 

Degree Age at start of study
of
inhalation 30-39 40-49 50-59 60-69
‘
Nonsmokers 1.00 1.00 1.00 1.00
Do not inhale 0.61 0.61 1.10 L78
Inhale smoke 129 1.12 1.58 211

 

SOURCE: Beat, E.W.R. (2).

TABLE 22.—Adjusted mortality ratios for males and females, by
tar and nicotine content of cigarettes usually

 

 

 

 

smoked
Mortality ratios
Sex “High” “Medium” “Low”
T/N T/N T/N
Males 1.00 0.94 0.85
Females 1.00 0.88 0.83
Total 1.00 0.91 0.84

 

SOURCE: Hammond, E.C. (19).

TABLE 23.—Adjusted mortality ratios for males and females
smoking low T/N cigarettes and subjects who never
smoked regularly

Mortality ratios

 

 

 

Sex
“Low” T/N Nonsmokers
Males 1.00 0.61
Females 1.00 0.74
Total 1.00 0.66

 

SOURCE: Hammond, E.C. (19).

was further reduced to 0.84 for the “low” T/N smokers. The mortality

ratios are lower for females than for males.
In a separate analysis, a comparison was also made between the

mortality ratios of “low” T/N smokers and nonsmokers. These data are
presented in Table 23. The mortality ratio of the “low” T/N group was
designated as 1.00. Nonsmokers have overall mortality ratios that are
about half those of “low” T/N smokers.

The combined data from these two tables are shown in Table 24.
Here, mortality ratios are calculated using nonsmokers as the

2—24
TABLE 24.—Overall mortality ratios of cigarette smokers
compared to nonsmokers, by sex and by tar and
nicotine content of cigarettes usually smoked

 

 

 

5 Non- “Low” “Medium” “High”
ex smokers T/N T/N T/N
Males 1.00 1.66 1.85 196
Females 1.00 1.37 1.45 1.65
Total 1.00 1.52 1.64 1.80

 

SOURCE: Hammond, E.C. (29).

reference. Combining these data from two separate analyses that are
not exactly comparable results in figures that are only approximate.

Hammond (19) also compared death rates of smokers of relatively
few (1-19) “high” T/N cigarettes with those of smokers who smoked
relatively large numbers (20-39) of “low” T/N cigarettes. The death
rates of these two groups were very similar and the difference
between them was not statistically significant.

Mortality and Female Cigarette Smokers

It is important that attention be called specifically to the mortality
that females experience as a result of cigarette smoking. There has
been an increase in smoking among teenage girls over the past 10
years. At present, the percentages of teenage boys smoking and
teenage girls smoking are nearly identical. For some ages, there are
more teenage girl smokers than boy smokers. Over the past 10 years,
there has been a gradual reduction in the percentage of the adult
population that is smoking. Men have quit in greater numbers than
women. There has been only a modest drop in the percentage of women
who are smoking. In Canada and several European countries, smoking
is decreasing among men but increasing among women. In the United
States, physicians, dentists, and pharmacists have been the most
successful professional groups in giving up smoking, but in the past
several years there has been an increase in smoking among nurses.

Several suggestions have been made as to why women do not quit
smoking. It may be that women do not generally perceive smoking as a
threat to their health. Lung cancer, heart attacks, and emphysema are
diseases that affect men more commonly than women. Women may
feel that they are in a low-risk group. Women took up smoking later
than men, generally smoked filter cigarettes, and smoked fewer
cigarettes per day than men. Lower overall death rates for women
smokers are due to lower exposure to cigarette smoke.

Cigarette smoking for some women may be symbolic of equality
with men. It is known that the smoking habits of women employed

2-25
TABLE 25.—Age-adjusted mortality ratios of female cigarette
smokers, by number of cigarettes smoked per day
and age. 25-State Study

 

 

Number of Age
cigarettes
per day 35-44 45-54 55-64 65-74 T5-8A
Nonsmokers 1.00 1.00 1.00 1.00 1.00
1-9 0.90 0.95 0.99 1.09 1.07
10-19 0.97 1.22 131 1.18 121
20-39 1.35 1.54 1.46 151 bd

 

SOURCE: Hammond, EC. (17).

outside the home match the smoking habits of men in various
occupations where men and women hold equal positions. Women with
the lowest rate of smoking are housewives who at present have few
male counterparts with whom to identify.

Recent surveys have shown that women are also concerned about
weight gain that may accompany quitting smoking. Any significant
weight gain on quitting represents an increased intake of food, but if
one watches the diet on smoking cessation, weight gain can be avoided;
in fact, weight loss can be achieved.

In recent years, a few investigators have studied the relationships
between cigarette smoking and the development of lung cancer and
coronary heart disease in women. Death rates for these diseases are
similar in women and men who have similar levels of exposure to
cigarette smoke; the associations are outlined in later chapters dealing
with specific diseases. Overall mortality rates for women available at
present are from studies initiated 10 to 20 years ago, and thus reflect
the differences in accumulated exposure that were operative at that
time.

Overall mortality in women varies in the same direction and ina
similar degree as men for the dosage variables commonly measured.
Overall mortality for women increases with the number of cigarettes
smoked per day (Tables 25, 26, and 27). Table 26 shows that the overall
mortality ratio is 2.19 for females smoking more than two packs a day
and inhaling moderately to deeply. Table 27 demonstrates that the
mortality ratio is 1.85 for females smoking more than two packs per
day who began smoking between the ages of 15 and 24. Mortality
ratios by “inhalation” and “age at start of study” are shown in Table
28. Noninhaling smokers have mortality ratios that are similar to
nonsmokers. Females with an average age of 50 who inhale smoke
deeply have a mortality ratio of 1.78.

Mortality and Ex-Smokers

There is a general recognition among smokers and nonsmokers alike
that cigarette smoking is a major cause of disease and death in the

2—26
TABLE 26.—Age-adjusted mortality ratios of female cigarette
smokers, by number of cigarettes smoked per day
and degree of inhalation. Subjects aged 45-54 at
start of study. 25-State Study

 

 

 

Number of Degree of inhalation of smoke
cigarettes
per day None-Slight Moderate-Deep
1-9 0.85 1.04
10-19 1.27 117
20-39 141 1.58
40+ bad 2.19

 

SOURCE: Hammond, E-C. (17).

TABLE 27.—Age-adjusted mortality ratios of female cigarette
smokers, by number of cigarettes smoked per day
and age began smoking. Subjects aged 45-54 at
start of study. 25-State Study

 

 

 

Number of Age began smoking
cigarettes

per day 25+ 15-24
Nonsmokers 1.00 1.00
1-9 0.95 0.88
10-19 1.17 1.23
20-39 1.38 1.61
40+ ” 1.85

 

SOURCE: Hammond, E.C. (17).

TABLE 28.— Age-adjusted mortality ratios of female cigarette
smokers, by number of cigarettes smoked per day
and degree of inhalation and age. 25-State Study

 

 

 

Degree Age
of
inhalation 35-44 45-54 55-64 65-74 75-84
Nonsmokers 1.00 1.00 1.00 1.00 1.00
None ** 1.01 111 112 0.96
Slight 1.22 1.21 1.28 1.26 1.21
Moderate 1.05 1.30 132 141 ”
Deep 1.40 178 1.64 *

 

 

 

SOURCE: Hammond, E.C. (27%.

United States. Smokers are now asking the question: “Will it help me
if T quit smoking?” Some of the first evidence concerning death rates
in ex-smokers required explanation. The data from the Hammond and
Horn study of men in nine States are presented in Table 29. It can be
Seen that the mortality ratios of ex-smokers were higher in the first
year after quitting than for continuing smokers. After the first year,

2—27
TABLE 29.—Age-adjusted mortality ratios for males who are ex-
smokers of cigarettes, by former amount smoked per
day and years since stopped smoking. Males in nine

 

 

 

States
Years since Cigarettes formerly
smoked per day

stopped

smoking 1-19 04
0 (Smokers) 161 2.02
Under 1 2.04 269
1-10 years 1.30 et
10+ years 1.08 150

 

SOURCE: Hammond, E.C. (20).

however, death rates for ex-smokers fell progressively so that after 10
years the former smokers of 1 to 19 cigarettes had a mortality ratio of
only 1.08.

The explanation for the higher death rates in the 1st year after
quitting is found in the fact that both healthy and sick individuals quit
smoking. The higher mortality ratio is experienced by those who quit
because of illness and not by those who quit for better health. In the
study of U.S. veterans, a differentiation was made between ex-
smokers who stopped smoking on the recommendation of a doctor and
those who quit for other reasons. About 10 percent of the smokers quit
on doctors’ orders; this group had much higher mortality ratios than
those who stopped for other reasons.

These data are presented in Table 30, where the mortality ratios for
ex-smokers by “years since stopping smoking,” “maximum amount
smoked,” “age began smoking,” and “reason for quitting” are
examined. There is a direct relationship between mortality rates and
the maximum amount smoked, an inverse relationship between
mortality and “years since stopped smoking,” and also an inverse
relationship between mortality and “age began smoking.”

A detailed analysis of the mortality experience of ex-smokers who
stopped for reasons other than doctors’ orders is given in Figures 1
through 4. This information is on ex-smokers, aged 55 to 64, from the
1954 cohort of the U.S. Veterans Study, who formerly smoked from 21
to 39 cigarettes per day. “Years since stopping smoking” is considered
as a variable and the mortality rates are compared with those of
current cigarette smokers and nonsmokers. Annual probabilities of
_dying are plotted on a logarithmic scale. This results in a fairly smooth
and linear pattern for both smokers and nonsmokers. These lines also
appear to be parallel, or perhaps to diverge slightly. This indicates an
approximately constant or slightly increasing excess risk of dying

2—28
TABLE 30.—Mortality ratios of ex-smokers of cigarettes only
who quit smoking on doctors orders and for other
reasons, by certain dosage variables. U.S. veterans
1954 cohort, 16-year followup

 

Years since stopped smoking

 

Mortality ratios

Years Quit for Quit on

since various doctors
stopped reasons orders
<5 1.23 1.55
5-9 123 1.43
10-14 1.14 LT
15-19 1.04 1.35
>19 1.06 1.16
Total 1.18 1.52

 

Number of cigarettes per day

Mortality ratios

No. of Quit for Quit on

cigarettes various doctors
per day reasons orders
<10 1.00 1.42
10-20 117 1.48
21-39 1.30 153
>39 1.32 1.60
Total 1.18 1.52

 

Age started smoking

 

Mortality ratios

Age Quit for Quit on
began various doctors
(years) reasons orders

<15 1.36 1.59
15-19 1.20 1.55
20-24 1.12 1.49
>2A 1.45 1.34
Total 1.18 1.52

 

SOURCE: Rogot, E. (33).

among smokers, compared to nonsmokers over the 16-year period. It
would be expected that the mortality experience of ex-smokers
initially would be similar to that of smokers, but with the passing of
time the mortality risk should move progressively closer to that of
nonsmokers. Figure 1 illustrates this. For ex-smokers who quit less
than 5 years prior to the beginning of the study, the mortality risk is at

2—29
first nearly identical to that of smokers. Over the years, the risk
gradually falls to a position approximately halfway between that of
smokers and nonsmokers. Figures 2 and 3 show that with longer
periods of cessation the mortality risk continues to approach that of
nonsmokers. In Figure 4, it can be seen that for ex-smokers who had
been off cigarettes for 15 or more years before the start of this study,
their mortality risk fluctuates about the mortality risk of nonsmokers
for the entire 16-year period.

The mortality experience of British doctors who were ex-smokers is
examined in Table 31. These data indicate that there are definite
benefits from quitting smoking no matter how long one has smoked.
After 10 to 15 years, ex-smokers have a risk of dying that is similar to
that of those who have never smoked. The risk of dying from ischemic
heart disease decreases rapidly immediately after stopping smoking,
whereas the risk of dying from lung cancer decreases more slowly.
Overall mortality measures the net benefit of quitting and, therefore,
drops more slowly than do death rates for certain disease categories.

Mortality and Pipe and Cigar Smoking

Pipe and cigar smokers have mortality rates that are similar to those of
cigarette smokers for cancers of the oral cavity, pharynx, larynx, and
esophagus. Pipe and cigar smokers have much lower death rates than
cigarette smokers for cancer of the lung, ischemic heart disease, and
chronic obstructive lung disease. Since these last three disease
categories account for the bulk of the excess mortality associated with
cigarette smoking, pipe and cigar smokers experience overall mortality
rates that are much lower than cigarette smokers. Inhalation of smoke
is necessary to expose the heart and lungs to the harmful constituents
found in tobacco smoke, and pipe and cigar smokers report much less
inhalation of smoke than cigarette smokers. Pipe smoke and cigar
smoke contain nearly all the same chemical compounds found in
cigarette smoke, but pipe and cigar smoke tends to be alkaline in pH
rather than acid as is cigarette smoke. Alkaline smoke is irritating to
the respiratory tract. This is likely to be an important reason why pipe
and cigar smokers report a much lower level of smoke inhalation than
cigarette smokers.

Table 32 summarizes the mortality ratios for male smokers by the
type of tobacco used for the five studies that obtained data on pipe and
cigar smoking. Cigar smokers have overall mortality ratios that are
from 6 to 25 percent higher than nonsmokers. Mixing cigarette
smoking with pipe or cigar smoking substantially increases the
mortality ratios, although they remain somewhat less than the
mortality ratios of cigarette-only smokers.

Dose-response relationships between overall mortality and the
amount of tobacco smoked were examined in several studies. Data

2—30
qx
9.0
6.0
7.0

6.0

5.0

4.0

3.0

2.0

1.0
0.9
0.68

0.7
0.6

0.5

ANNUAL PROBABRITY OF DYING (in %) LOG SCALE

0.4

0.3

02

0.1

 

 

i
_
OQ --0 Never Smoked
r- o-—@ Ex-cigarette smokers
Stopped less than § years ago
Maximum amount smoked, 21-39 cigarettes per day.
@—® Curent cigarette smokers,
Smoking 21-39 cigarettes per day.
} Loto tt

 

Lop yd
123 4 5 6 7 8 9 10 1112 13 14 15 16

YEARS OF FOLLOWUP

FIGURE 1.—Annual probability of dying for ex-smokers who quit
smoking less than 5 years, current cigarette smokers and nonsmokers,

aged 55-64, U.S. veterans 1954 cohort, 16-year follow-up
SOURCE: Rogot, E. (83).

2—31
Qx

8.0
7.0 --

6.0 --

5.0 --

40r

3.0

2.0

1.0
0.9 f-
068

0.7

 

0.6

O---0 Never Smoked

ANNUAL PROBABILITY OF DYING (in %) LOG SCALE

04 f- @——«@ Ex-cigarette smokers
Stopped 5-9 years
Maximum amount smoked 21-39 cigarettes per day.

@——@ Current cigaretie smokers,
Smoking 21-39 cigarettes per day.
0.2

 

Lepypy Litt tp
12345 67 & 9 10 111253 14 18 16
YEARS OF FOLLOWUP

0.1

FIGURE 2.—Annual probability of dying for ex-smokers who quit
smoking 5-9 years, current cigarette smokers and nonsmokers, aged

55-64, U.S. veterans 1954 cohort, 16-year follow-up
SOURCE: Rogot, E. ($3).

2—32
qx
8.0
8.0

7.0

6.0.

5.0

4.0

3.0

2.0

1.0
0.9
06

07
0.6

05

ANNUAL PROBABILITY OF DYING (in %) LOG SCALE

04

03

0.2

0.1

=

 

 

O---0 Never Smoked

@——-@ Ex-cigarette smokers
Stopped 10-14 years
Maximum amount smoked 21-39 cigarettes per day.

@—@ Current cigarette smokers,
Smoking 21-39 cigarettes per day.

bot Jp tt
123 4 5 6 7 & 9 10 1112 13 14 15 16
YEARS OF FOLLOWUP

FIGURE 3.—Annual probability of dying for ex-smokers who quit
10-14 years, current cigarette smokers and nonsmokers, aged 55—64,

US. veterans 1954 cohort, 16-year follow-up
SOURCE: Rogot, E. (83).

2—33
ax
9.0
8.0

7.0
6.0

5.0

40

3.0
uw
2
e 20
8
z
&
g
5
oO ¢.
5 08
— os
a
2 0.7
Bos
a
Zz 05
>
2
3
= 04

0.3

02

 

 

J
1

O- --O Never Smoked

o-——@ Ex-cigaretie smokers.

Stopped 15 or more years ago

Maximum amount smoked 21-39 cigarettes per day.

@-——® Current cigarette smokers,

Smoking 21-39 cigarettes per day.

jj} tt

a
23 4 5 6 7 8 °9 10 1112 13 14 15 16

YEARS OF FOLLOWUP

i

4.

}

'
a,

FIGURE 4.—Annual probability of dying for ex-smokers who quit
15+ years, current cigarette smokers and nonsmokers, aged 55-64,
U.S. veterans 1954 cohort, 16-year follow-up

SOURCE: Rogot, E. ($3).

2—34
TABLE 31.—Mortality ratios of ex-smokers compared to
nonsmokers, by age and number of years since
stopping smoking. Study of British doctors

 

 

: Mortality ratios

Years since
stopping Ages Ages All
smoking 30-64 65+ ages
0 (Current smokers) 2.0 16 18
1-4 17 14 15
5-9 16 14 15
10-14 14 12 13
15+ 11 Ll ll
Nonsmokers 1.0 1.0 10

 

SOURCE: Doll, R. (8).

TABLE 32.—Mortality ratios for male smokers, by type of

 

 

tobacco used
Non- Cigar Pipe Cigar Cigarette rette

Study smoker onl onl & pi & cigar onl

ly y Pipe oF pipe y

Men in 9 States(20) 1.00 1.2 1.12 1.10 1.43 1.68
British Doctors(4) 1.00 “ “ 1.09 131 1.73
Canadian Veterans() 1.00 1.06 1.05 0.98 1.13 1.54
US, Veterans(26) 1.00 116 1.07 1.08 1.51 1.55
Males in 25 States(17) 1.00 1.25 1.19 1.01 157 1.86

 

from the study of men in nine States, Canadian veterans, and the ACS

-State Study are presented in Tables 33 through 35. There is a dose-
response relationship evident for cigar smoking that is small but found
consistently. There was no clear dose-response relationship for pipe
smoking. Data from the U.S. Veterans Study are presented in Tables
36 through 39. Again, there appears to be a dose-response relationship
for cigar smoking, both for the number of cigars smoked per day and
for the age began smoking cigars. For pipe smokers, a dose-response
relationship was found for the number of pipefuls per day, but not for
the age began smoking.

The U.S. Veterans Study (31) contains the most detailed information
on pipe, cigar, and cigarette smoking in various combinations and in
various sequences. These data on mortality ratios are shown in Table
40 and have been arranged by “increasing risk of mortality.” The first
Section shows the mortality experience of current cigarette smokers by
the present, past, or nonuse of pipes and cigars. Cigarette smokers who
have the lowest mortality ratio of 1.21 are those who also currently
Smoke both pipes and cigars. Current cigarette smokers who formerly
Smoked pipes and cigars have a mortality ratio of 1.48, which is only

2—35
TABLE 33.—Age-adjusted mortality ratios for male cigar and
pipe smokers, by amount smoked. Males in nine

 

 

States
Type and Mortality
amount ti
smoked a
Nonsmokers 1.00
Cigar only
1-4 per day 1.08
4+ per day 1.24
All cigar smokers 1.09
Pipe only
1-10 pipefuls per day 1.05
10+ pipefuls per day 119
All pipe smokers 1.09

 

SOURCE: Hammond, E.C. (20).

TABLE 34.—Age-adjusted mortality ratios for male cigar and
pipe smokers, by amount smoked. Canadian veterans

 

 

Type and Mortality

amount .

smoked also

Nonsmokers 1.00
Cigar only

1-2 per day 114

3-10 per day 1.19
Pipe only

1-10 pipefuls per day 1.01

10+ pipefuls per day 1.00

 

SOURCE: Best, E.W.R. (2).

slightly below the mortality ratio of 1.55 of cigarette-only smokers who

have never smoked pipes or cigars.
The second section of Table 40 shows that the mortality ratios of

current cigar smokers are slightly decreased among those also
currently smoking pipes and significantly increased among those also
currently smoking cigarettes. The third section shows that pipe
smokers with the lowest mortality are those who have never smoked
cigarettes or cigars. Mortality ratios increase slightly with the addition
of current cigar smoking and jump moderately with the addition of
current cigarette smoking.

2—36
TABLE 35.—Age-adjusted mortality ratios for male cigar and
pipe smokers, by amount smoked. Males in 25

 

 

States
Type and Mortality
amount ratio
smoked
Nonsmokers 1.00
Cigar only
144 per day 1.08
4+ per day 1.18
All cigar smokers 1.09
Pipe only
1-9 pipefuls per day 1.08
9+ pipefuls per day 0.92
All pipe smokers 1.04

 

SOURCE: Hammond, E.C. (1%.

TABLE 36.—Age-adjusted mortality ratios of current smokers of
cigars only, by amount smoked. U.S. veterans 1954
cohort, 16-year followup

No. of

 

: Mortalit:
oagars ratio .

per day

Nonsmokers 1.00

1-2 1.11
34 118
58 1.22
9+ 1.39
Total 116

 

SOURCE: Rogot, E. (88).

TABLE 37.—Age-adjusted mortality ratios of current smokers of
cigars only, by age began smoking. U.S. veterans
1954 cohort, 16-year followup

Age

 

began Mortality

ratio
(years)

Nonsmokers 1.00
<15 1.22
15-19 1.23
20-24 1.16
>a 1.13
Total 1.16

 

 

SOURCE: Rogot, E. (33).

Mortality by Cause of Death
The underlying cause of death was obtained from the death certificate

2—37