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Prevalence of cigarette smoking among subsequent cohorts of Italian males and females
PREVENTIVE
MEDICINE
Prevalence
15,
606-613 (1986)
of Cigarette Smoking among Subsequent of Italian Males and Females’
Cohorts
ADRIANO DECARLI, Sc.D.,t PAGANO, PH.D.S
CARLO LA VECCHIA, M.D.,*,*
ANDROMANO
*“Mario Negri” Institute for Pharmacological Research, Via Eritrea, 62-20157 Milan, I-Institute of Medical Statistics, University of Milan, and National Cancer Institute, Via Venezian l-20133 Milan, and #Central Institute of Statistics (ISTAT), Via/e Liegi, 11-00100 Rome, Italy Prevalence of cigarette smoking among successive cohorts of Italian males and females born between 1890 and 1969 was estimated from data of the 1983 National Health Survey (based on 89,765 persons randomly selected within strata of geographical area, size of place of residence, and size of household), opportunely corrected for excess mortality of smokers. The overall participation rate for the original sample was 93.6%; impossibility of tracing or refusal of the interview led to substitution of 2,058 households. Among males, smoking prevalence in the young and middle-aged increased steadily up to the generation born in 1920-1929, which, in its 3Os, showed the highest absolute smoking prevalence (68.3% in 1960). Moderate declines followed, chiefly on a calendar-period basis (i.e., between 1970 and 1980 in each birth cohort). These declines occurred later and at a lower rate than in several other Western countries. Among females, cigarette smoking was extremely rare for those generations born at the turn of the century (only about 3% of Italian females born in 1890-1899 ever smoked), but increased steadily in each birth cohort and calendar period to reach a rate only about one-third lower than that of males in the 1960-1969 cohort. 0 1986 Academic Press, Inc.
INTRODUCTION
Among the 554,000 deaths registered in Italy in 1983, 25,300 were due to lung cancer, about 19,000 to other tobacco-related neoplasms, over 15,000 to chronic obstructive lung disease, and 79,000 to ischemic heart disease (8). Furthermore, tobacco-related cancers, and among males ischemic heart disease, were among the few causes of death showing consistent upward trends over the past two or three decades, when overall mortality rates decreased steadily (14, 15). Analysis of cigarette smoking patterns among various generations of Italian males and females is therefore of interest in order to understand and quantify the increasing importance of cigarette smoking on past and current mortality trends. Further, recent patterns of cigarette smoking among younger generations may offer important clues to future trends in morbidity and mortality from tobacco-related diseases (4). In this article, we analyze the prevalence of cigarette smoking among subsequent cohorts of Italian males and females on the basis of data collected by the t This work was conducted within the framework of the CNR (Italian National Research Council) Applied Projects “Oncology” Contract 84.00639.44, and “Preventive and Rehabilitative Medicine” Contracts 84.02233.56 and 84.02299.56. * To whom reprint requests should be addressed. 606 0091-7435/86 $3.00 Copyright 0 1986 by Academic Press, Inc. All rights of reproduction in any form reserved.
CIGARETTE
SMOKING
Central Institute of Statistics Survey (NHS) (9).
within the context
MATERIALS
The 1983 National
Health
PREVALENCE
607
IN ITALY
of the 1983 National
Health
AND METHODS
Survey
The second National Health Survey (9) was conducted by the Central Institute of Statistics during the week between November 28 and December 3, 1983. A sample of 31,025 households (a total of 89,753 persons) was randomly selected within strata of geographical area (region), municipality size, and household size in order to be representative of the general Italian population. Interviews were arranged and conducted by civil servants (appointed by each municipality included in the study) within the homes of the families identified. Impossibility of tracing or refusal of the interview led to the substitution of 2,058 households, thus giving an overall participation rate for the original sample of 93.4%. Proxy interviews were permitted for members not present in the house. Information was collected on sociodemographic characteristics, prevalence of 19 diseases or groups of diseases, health service utilization during the month (for outpatient procedures) or the year (for inpatient procedures) preceding the interview, smoking habits, and alcohol consumption. We obtained from the Central Institute of Statistics copies of the original computer tapes including, for each subject, sociodemographic data (sex, date of birth, province of residence, education, and occupation) and smoking-related variables: smoking status, forms of tobacco smoked, age at starting and (for ex-smokers) at stopping smoking, and current number of cigarettes (or cigars/pipes) smoked per day, The total number of subjects included in this analysis, stratified for sex and birth cohort (from 1890-1899 to 1960-1969), is reported in Table 1. Subjects born before 1890 or after 1969 were not considered further. Data Analysis and Correction
for Excess Mortality
in Smokers
To estimate the prevalence of cigarette smoking for each birth cohort and calendar year, we computed the ratio of the number of cigarette smokers in that TABLE
1
NUMBERSOFSUBJECTS INCLUDEDINTHECENTRALINSTITUTEOFSTATISTICS' HEALTHSURVEYACCORDINGTOBIRTH COHORTANDSEX Birth
cohort
Males
272 1,663 3,286
1890-1899 1900- 1909 1910-1919 1920-1929 1930-1939 1940- 1949 1950- 1959 1960- 1969
5,782 5,995 5,848 6,981
Total
35,242
5,415
1983 NATIONAL Females
528 2.424 3,810
5,919 6,027 6,038 6,105
7,020 37,871
608
LA
VECCHIA,
DECARLI,
AND
PAGAN0
particular year to the total number of subjects in each birth cohort. Subjects who reportedly smoked only pipes or cigars were considered nonsmokers. Since available data referred only to smoking histories of persons alive in 1983, a major problem was posed by the correction for excess mortality among smokers in the absence of Italian data on differential mortality rates for smokers and nonsmokers. We therefore relied on the assumption [derived chiefly from British and American cohort studies (2, 3, 6, 1 I)] that the mortality ratio for male cigarette smokers was 2.0 below age 65 and 1.5 above age 65. For female smokers, the ratios adopted were 1.6 below age 55, 1.25 between ages 55 and 65, and 1.03 above age 65. Death rates for smokers and nonsmokers at each year of age were then derived on the basis of standard life tables for the whole Italian population (10) for the period 1977- 1979 using the equation + r;(l
r = K.r;p
-p),
[II
where Y is the overall death rate, K is the excess mortality ratio for smokers as reported above, and p is the proportion of smokers. Simplifying Eq. [ 11, the mortality rate for nonsmokers (m) becomes r, =
r K*p+
1 -p
RI
’
The prevalence of cigarette smoking at time t - 1 (ptel) in the absence of changes in the number of current smokers can then be estimated on the basis of the prevalence at time t (p,) as Pt-l
= Pt(l
(1 - 4 - K.r,)
’
Since 49% of the 5,738 ex-smokers had stopped smoking because of the presence of some smoking-related disease (9), we assumed that their mortality rates were equal to those of current smokers up to 10 years after cessation of smoking. Thereafter, mortality rates for ex-smokers were considered equal to those of nonsmokers. RESULTS
The prevalences of cigarette smoking for subsequent birth cohorts of Italian males and females for the calendar period 1910-1980, estimated from the 1983 National Health Survey, are reported in Tables 2 and 3, respectively. The experience of each birth cohort runs vertically and of each calendar period runs horizontally, and prevalences for comparable age groups in various cohorts run diagonally. For instance, in the top diagonal line, smoking prevalence is reported for populations in subsequent cohorts at ages lo- 19, in the second diagonal from the top, prevalence for populations at ages 20-29, and so on. Among males, smoking prevalence among the young and middle ages is seen to have increased steadily up to the generation born between 1920 and 1929, which, in its 30s showed the highest absolute smoking prevalence (68.3% in 1960). In the youngest age group (lo-19 years), the estimated prevalence peaked in the 1950-1959 cohort, but in successive age groups moderate tendencies toward a
CIGARETTE
SMOKING
PREVALENCE TABLE
609
IN ITALY
2
ESTIMATEDPREVALENCE(%)OFCIGARETTESMOKINGAMONGSUBSEQUENTBIRTHCOHORTSOF ITALIANMALES, DERIVEDFROMTHECENTRALINSTITUTEOFSTATISTICS' 1983 NATIONALHEALTH SURVEY Birth cohort Calendar yearY 1910 1920 1930 1940 1950
1960 1970
B January
1890-1899
1900-1909
1910-1919
6.3 48.9 55.6 53.7 43.6 38.4 34.0 18.4
10.4 57.3 58.9 55.2 53.3 44.6 30.1
15.6 59.9 63.2 60.6 54.5 41.1
1 of each
year
(i.e..
-
excluding
people
1920-1929
1930-1939
1940-1949
14.3 64.9 68.3 62.6 52.2 who started
-
-
15.1 59.8 61.2 55.9
13.8 59.8 57.3
or stopped
smoking
1950-1959
1960-1969
-
-
-
-
17.8 55.3
12.7
in that particular
year).
decline in prevalence became apparent (for instance, smoking prevalence at ages 30-39 declined from 68.3% in 1960 for the 1920- 1929 cohort to 57.3% in 1980 for the 1940- 1949 cohort). Smoking cessation increased between 1970 and 1980 among all age groups, including the youngest, thus superimposing a period effect on the obvious age effect in stopping smoking. As a consequence, the decline in prevalence was evident at a progressively earlier age in each successive cohort, and smoking rates among males born in 1940-1949 were already lower at ages 30-39 than at ages 20-29. The pattern for Italian females is quite different, since smoking was extremely uncommon among females at the beginning of the century, and smoking rates increased progressively among subsequent cohorts. Further, a period effect was superimposed on the age and cohort effects for starting smoking, so that smoking rates have tended to be higher at later and middle ages than at younger ages, contrary to the picture among males. For instance, the highest estimated prevalence for females born between 1900 and 1929 was registered between ages 50 and TABLE
3
ESTIMATEDPREVALENCE(%)OFCIGARE~ESMOKINGAMONGSUBSEQUENTBIRTHCOHORTSOF ITALIAN FEMALES,DERIVEDFROMTHECENTRALINSTITUTEOFSTATISTICS' 1983 NATIONALHEALTH SURVEY Birth cohort Calendar yeaP 1910 1920
1930 1940 1950 1960
1970 1980
1890-1899 0.2 1.6 2.4 2.6 2.4 2.0 1.5 1.1
1900-1909 0.3 2.5 3.8 4.5 4.5 4.1 3.0
1910-1919
1920-1929
-
-
0.9 5.1 7.2 7.8 8.3 6.8
1.0 8.0 11.3 12.1 12.5
1930-1939
1940-1949
-
a January 1 of each year (i.e.. excluding people who started or
1950-1959
1960-1969
1.7 11.4 15.7 17.4 stopped
-
2.3 20.3 25.2 smoking
5.9 32. I
in that particular
-
8.0 year).
610
LA
VECCHIA,
DECARLI,
AND
PAGAN0
59, and only after age 60 did subjects stopping smoking outnumber those starting. Consequently, age at starting smoking tends, on average, to be considerably later among female smokers. The continuous and progressive increase in smoking prevalence among women led to a substantial reduction of the male-to-female difference in smoking habits, from over 20-fold for the 1890-1899 cohort to about 37% for that born in 1960- 1969. We repeated similar analyses separately for the 14 Italian provinces including large urban concentrations (over 250,000 inhabitants in 1981) and for the remaining 81 provinces. Among males, estimated prevalences tended to be higher in those provinces that included urban concentrations for the younger age groups (ages 10 to 19), mostly in earlier cohorts (i.e., 12.8 vs 9.3% for the 1900-1909 cohort, 16.8 vs 15.0% for the 1910-1919 cohort), but little difference was observed in the subsequent age groups. Among females, striking differences were observed between urban concentrations and chiefly rural areas, since smoking diffusion was seen earlier in urban areas. Overall urban-rural differences were over 100% for the cohorts born before 1909, were over 50% for those born between 1910 and 1939, and tended to level off only in more recent generations. For instance, the highest estimated prevalences in provinces including urban concentrations were 7.6, 10.2, 17.1, and 21.5% for the 1900-1909, 1910-1919, 1920- 1929, and 1930- 1939 cohorts, respectively. Comparable figures for chiefly rural areas were 3.2, 6.7, 10.4, and 15.1%, respectively. DISCUSSION
According to the present analysis of data from the 1983 National Health Survey, the highest smoking prevalences among males were observed among the 1920-1929 generation, followed by moderate declines, chiefly on a calendar-period basis (i.e., between 1970 and 1980 in each birth cohort). Among females, cigarette smoking was extremely rare for generations born at the turn of the century (only about 3% of females born between 1890 and 1889 ever smoked), but increased in each birth cohort and calendar period to reach a rate only about one-third lower than that of males in the 1960- 1969 cohort. The prevalence rates presented are based on information collected in 1983 on a sample of live persons, and are therefore subject to several potential sources of bias. The problems are minor for more recent cohorts, since estimates are derived from large numbers and the effect of differential mortality of smokers and nonsmokers is negligible. The problems become progressively larger with earlier cohorts. Random variation, however, is still limited up to the 1900- 1909 cohort, at least among males (95% confidence intervals, based on the Poisson approximation, being around +3% of the rates presented for the 1900-1909 cohort). The major uncertainties relate to the 1890- 1899 cohort, since random variation is considerable (95% confidence intervals being around &20% of the rates in males), and the effect of correction for excess mortality among smokers is substantial (for instance, the crude prevalence of 40% in 1920 increased to 49% after correction). It is possible that these estimates are overcorrected, since we applied excess mor-
CIGARETTE
SMOKING
PREVALENCE
611
IN ITALY
tality ratios derived from British and American studies to an Italian population which smoked smaller numbers of cigarettes, at least at younger ages (12). Data on cohorts born after 1910 are more reliable, and estimates for younger males obtained by the present analysis appear to be in satisfactory agreement with a survey conducted in 1965 (5) by a private marketing research institute on a randomly selected sample of 6,095 subjects (Table 4). However, the 1965 smoking rate for males ages 45-54 derived from the 1983 NHS is lower than that obtained from contemporary interview data. This can be attributed to differences in sampling methods or to random variation (the 1965 Doxa survey was relatively small), but might also be due to a systematic tendency toward underreporting smoking over more recent periods (13), which may have led to anticipating the date of smoking cessation in some cases. With reference to a comparison with other Western countries (4, 7, 17), the Italian data show a delayed increase in smoking prevalence among males born at the turn of the century [mostly with respect to British data (4, 17)]. Also, the recent decline in smoking has been somewhat limited and has occurred later in Italy, where it was first observed among middle-aged males only during the 1970s. For females, the Italian pattern was largely different from that of most other Western countries (4, 7, 17), since smoking prevalence was markedly lower among Italian females born before the second world war. However, the increase among more recent cohorts has been extremely rapid, and smoking prevalence among younger Italian females in 1980 was not substantially different from that in other Western countries. Application of the present study to any interpretation of trends in mortality from tobacco-related diseases is not immediate, since an accurate measure of cigarette smoke exposure would reflect not only prevalence but also dosage of cigarette smoking. A few useful indications can nevertheless be derived from the present analysis. For instance, the observation that smoking prevalence was extremely low in the younger age groups among females born before the second world war compares well with the limited upward trends registered in mortality rates from lung and other tobacco-related neoplasms for the same cohorts of females (1, 14), since it is known that smoking habits in early life are a strong
TABLE 4 COMPARISON OF ESTIMATED PREVALENCES OF CIGARETTE SMOKING IN 1965 DERIVED FROM THE 1983 NATIONAL HEALTH SURVEY (NHS) WITH THOSE FROM A CONTEMPORARY MARKET SURVEY [DOXA, 1965; (5)] Estimated
prevalence
(7%) of cigarette
smoking
Males Age group
1983 NHS
25-34 35-44 45-54
60.5 66.4 58.6
a Excluding
“occasional”
smokers.
in 1965 Females
Doxa, 59.6 67.1 65.2
1965
1983 NHS 13.5 11.7 8.0
Doxa, 9.1 10.6 7.5
196.50
612
LA VECCHIA,
DECARLI,
AND PAGAN0
determinant of subsequent cancer risk (4). Among Italian males, lung cancer mortality increased markedly in each successive birth cohort from 1890 to 1930 and leveled off thereafter, up to a small decline for the 1950 cohort (1, 12, 14). This pattern, too, is in agreement with the evolving prevalence of cigarette smoking among subsequent birth cohorts. In conclusion, the present analysis of data from the 1983 National Health Survey shows considerable delays both in the spread of smoking among females and in the decline of smoking among males in Italy, compared with several other Western countries. These phenomena seem to be largely affected by cultural and economic factors, rather than by knowledge of the health consequences of smoking which has accumulated over the past three decades. Quantitative information on the health risks associated with smoking is therefore urgently needed to contrast, as much as possible, the delayed spread of the smoking-related disease epidemics in Italy, the consequences of which are already evident in national mortality data: For instance, Italian lung cancer death certification rates among young and middle-aged males are currently among the highest in any developed country (16). ACKNOWLEDGMENTS The contributions of the Italian Association for Cancer Research and of the Italian League against Tumors, Milan, Italy, are gratefully acknowledged. We thank Ms. Judy Baggott and Ms. Antonella Palmiero for editorial assistance.
REFERENCES 1. Decarli, A., La Vecchia, C., Cislaghi, C., Fasoli, M., Mezzanotte, G., and Negri, E. Cancer mortality in Italy, 1955- 1979: Effects of age, birth cohort and period of death. La mortalita per tumori in Italia: Effetti dell’eta, della generazione di nascita e del period0 di morte. Lega Italiana per la Lotta Contro i Tumori, Milano, (1986). 2. Doll, R., Gray, R., Hafner, B., and Peto, R. Mortality in relation to smoking: 22 years’ observations on female British doctors. Brit. Med. J. 280, 967-971 (1980). 3. Doll, R., and Peto, R. Mortality in relation to smoking: 20 years’ observations on male British doctors. Brit. Med. J. 2, 1525-1536 (1976). 4. Doll, R., and Peto, R. The causes of cancer: Quantitative estimates of avoidable risks of cancer in the United States today. J. Natl. Cancer Inst. 66, 1191- 1308 (1981). 5. Doxa. I fumatori in Italia. Una nuova indagine sui fumatori. Boll. Doxa 20, Nos. 20-21 (1966). 6. Hammond, E. C. Smoking in relation to the death rates of one million men and women. Natl. Cancer Inst. Monogr. 19, 127-204 (1966). 7. Harris, J. E. Cigarette smoking among successive birth cohorts of men and women in the United States during 1900-80. J. Natl. Cancer Inst. 71, 473-479 (1983). 8. Istituto Centrale di Statistica (ISTAT). Andamento demografico e sanitario. Notiziario ISTAT 5, Nos. 9-11 (1984). 9. Istituto Centrale di Statistica. Indagine statistica sulle condizioni di salute della popolazione e sul ricorso ai servizi sanitari-1983. Primi risultati. Notiziario ISTAT 4, No. 8 (1984). IO. Istituto Centrale di Statistica. Tavole di mortalita della popolazione Italiana per regione. 1977-79. Boll. Mensile Statist. 16 (Suppl.) (1983). 11. Kahn, H. A. The Dorn study of smoking and mortality among U.S. veterans: Report on eight and one-half years of observations. Nat/. Cancer Inst. Monogr. 19, 1-125 (1966). 12. La Vecchia, C. Patterns of cigarette smoking and trends in lung cancer mortality in Italy. J. Epidemiol. Community Health 39, 157-164 (1985). 13. La Vecchia, C. Smoking in Italy, 1949-1983. Prev. Med. 15, 274-281 (1986).
CIGARETTE
SMOKING
PREVALENCE
IN ITALY
613
14. La Vecchia, C., and Decarli, A. Trends in cancer mortality in Italy, 1955- 1978. Tumori 71, 201-218 (1985). 15. La Vecchia, C., and Decarli, A. Trends in ischemic heart disease mortality in Italy 1968-1978. Amer.
J. Public
Healfh
76, 454-456
(1986).
16. La Vecchia, C., and Franceschi, S. Italian lung cancer death rates in young males. Lancer
1, 406
(1984). 17.
Office of Population, Censuses and Surveys. Cigarette smoking: 1972 to 1982. OPCS Moniror, 5 July (1983).
MEDICINE
Prevalence
15,
606-613 (1986)
of Cigarette Smoking among Subsequent of Italian Males and Females’
Cohorts
ADRIANO DECARLI, Sc.D.,t PAGANO, PH.D.S
CARLO LA VECCHIA, M.D.,*,*
ANDROMANO
*“Mario Negri” Institute for Pharmacological Research, Via Eritrea, 62-20157 Milan, I-Institute of Medical Statistics, University of Milan, and National Cancer Institute, Via Venezian l-20133 Milan, and #Central Institute of Statistics (ISTAT), Via/e Liegi, 11-00100 Rome, Italy Prevalence of cigarette smoking among successive cohorts of Italian males and females born between 1890 and 1969 was estimated from data of the 1983 National Health Survey (based on 89,765 persons randomly selected within strata of geographical area, size of place of residence, and size of household), opportunely corrected for excess mortality of smokers. The overall participation rate for the original sample was 93.6%; impossibility of tracing or refusal of the interview led to substitution of 2,058 households. Among males, smoking prevalence in the young and middle-aged increased steadily up to the generation born in 1920-1929, which, in its 3Os, showed the highest absolute smoking prevalence (68.3% in 1960). Moderate declines followed, chiefly on a calendar-period basis (i.e., between 1970 and 1980 in each birth cohort). These declines occurred later and at a lower rate than in several other Western countries. Among females, cigarette smoking was extremely rare for those generations born at the turn of the century (only about 3% of Italian females born in 1890-1899 ever smoked), but increased steadily in each birth cohort and calendar period to reach a rate only about one-third lower than that of males in the 1960-1969 cohort. 0 1986 Academic Press, Inc.
INTRODUCTION
Among the 554,000 deaths registered in Italy in 1983, 25,300 were due to lung cancer, about 19,000 to other tobacco-related neoplasms, over 15,000 to chronic obstructive lung disease, and 79,000 to ischemic heart disease (8). Furthermore, tobacco-related cancers, and among males ischemic heart disease, were among the few causes of death showing consistent upward trends over the past two or three decades, when overall mortality rates decreased steadily (14, 15). Analysis of cigarette smoking patterns among various generations of Italian males and females is therefore of interest in order to understand and quantify the increasing importance of cigarette smoking on past and current mortality trends. Further, recent patterns of cigarette smoking among younger generations may offer important clues to future trends in morbidity and mortality from tobacco-related diseases (4). In this article, we analyze the prevalence of cigarette smoking among subsequent cohorts of Italian males and females on the basis of data collected by the t This work was conducted within the framework of the CNR (Italian National Research Council) Applied Projects “Oncology” Contract 84.00639.44, and “Preventive and Rehabilitative Medicine” Contracts 84.02233.56 and 84.02299.56. * To whom reprint requests should be addressed. 606 0091-7435/86 $3.00 Copyright 0 1986 by Academic Press, Inc. All rights of reproduction in any form reserved.
CIGARETTE
SMOKING
Central Institute of Statistics Survey (NHS) (9).
within the context
MATERIALS
The 1983 National
Health
PREVALENCE
607
IN ITALY
of the 1983 National
Health
AND METHODS
Survey
The second National Health Survey (9) was conducted by the Central Institute of Statistics during the week between November 28 and December 3, 1983. A sample of 31,025 households (a total of 89,753 persons) was randomly selected within strata of geographical area (region), municipality size, and household size in order to be representative of the general Italian population. Interviews were arranged and conducted by civil servants (appointed by each municipality included in the study) within the homes of the families identified. Impossibility of tracing or refusal of the interview led to the substitution of 2,058 households, thus giving an overall participation rate for the original sample of 93.4%. Proxy interviews were permitted for members not present in the house. Information was collected on sociodemographic characteristics, prevalence of 19 diseases or groups of diseases, health service utilization during the month (for outpatient procedures) or the year (for inpatient procedures) preceding the interview, smoking habits, and alcohol consumption. We obtained from the Central Institute of Statistics copies of the original computer tapes including, for each subject, sociodemographic data (sex, date of birth, province of residence, education, and occupation) and smoking-related variables: smoking status, forms of tobacco smoked, age at starting and (for ex-smokers) at stopping smoking, and current number of cigarettes (or cigars/pipes) smoked per day, The total number of subjects included in this analysis, stratified for sex and birth cohort (from 1890-1899 to 1960-1969), is reported in Table 1. Subjects born before 1890 or after 1969 were not considered further. Data Analysis and Correction
for Excess Mortality
in Smokers
To estimate the prevalence of cigarette smoking for each birth cohort and calendar year, we computed the ratio of the number of cigarette smokers in that TABLE
1
NUMBERSOFSUBJECTS INCLUDEDINTHECENTRALINSTITUTEOFSTATISTICS' HEALTHSURVEYACCORDINGTOBIRTH COHORTANDSEX Birth
cohort
Males
272 1,663 3,286
1890-1899 1900- 1909 1910-1919 1920-1929 1930-1939 1940- 1949 1950- 1959 1960- 1969
5,782 5,995 5,848 6,981
Total
35,242
5,415
1983 NATIONAL Females
528 2.424 3,810
5,919 6,027 6,038 6,105
7,020 37,871
608
LA
VECCHIA,
DECARLI,
AND
PAGAN0
particular year to the total number of subjects in each birth cohort. Subjects who reportedly smoked only pipes or cigars were considered nonsmokers. Since available data referred only to smoking histories of persons alive in 1983, a major problem was posed by the correction for excess mortality among smokers in the absence of Italian data on differential mortality rates for smokers and nonsmokers. We therefore relied on the assumption [derived chiefly from British and American cohort studies (2, 3, 6, 1 I)] that the mortality ratio for male cigarette smokers was 2.0 below age 65 and 1.5 above age 65. For female smokers, the ratios adopted were 1.6 below age 55, 1.25 between ages 55 and 65, and 1.03 above age 65. Death rates for smokers and nonsmokers at each year of age were then derived on the basis of standard life tables for the whole Italian population (10) for the period 1977- 1979 using the equation + r;(l
r = K.r;p
-p),
[II
where Y is the overall death rate, K is the excess mortality ratio for smokers as reported above, and p is the proportion of smokers. Simplifying Eq. [ 11, the mortality rate for nonsmokers (m) becomes r, =
r K*p+
1 -p
RI
’
The prevalence of cigarette smoking at time t - 1 (ptel) in the absence of changes in the number of current smokers can then be estimated on the basis of the prevalence at time t (p,) as Pt-l
= Pt(l
(1 - 4 - K.r,)
’
Since 49% of the 5,738 ex-smokers had stopped smoking because of the presence of some smoking-related disease (9), we assumed that their mortality rates were equal to those of current smokers up to 10 years after cessation of smoking. Thereafter, mortality rates for ex-smokers were considered equal to those of nonsmokers. RESULTS
The prevalences of cigarette smoking for subsequent birth cohorts of Italian males and females for the calendar period 1910-1980, estimated from the 1983 National Health Survey, are reported in Tables 2 and 3, respectively. The experience of each birth cohort runs vertically and of each calendar period runs horizontally, and prevalences for comparable age groups in various cohorts run diagonally. For instance, in the top diagonal line, smoking prevalence is reported for populations in subsequent cohorts at ages lo- 19, in the second diagonal from the top, prevalence for populations at ages 20-29, and so on. Among males, smoking prevalence among the young and middle ages is seen to have increased steadily up to the generation born between 1920 and 1929, which, in its 30s showed the highest absolute smoking prevalence (68.3% in 1960). In the youngest age group (lo-19 years), the estimated prevalence peaked in the 1950-1959 cohort, but in successive age groups moderate tendencies toward a
CIGARETTE
SMOKING
PREVALENCE TABLE
609
IN ITALY
2
ESTIMATEDPREVALENCE(%)OFCIGARETTESMOKINGAMONGSUBSEQUENTBIRTHCOHORTSOF ITALIANMALES, DERIVEDFROMTHECENTRALINSTITUTEOFSTATISTICS' 1983 NATIONALHEALTH SURVEY Birth cohort Calendar yearY 1910 1920 1930 1940 1950
1960 1970
B January
1890-1899
1900-1909
1910-1919
6.3 48.9 55.6 53.7 43.6 38.4 34.0 18.4
10.4 57.3 58.9 55.2 53.3 44.6 30.1
15.6 59.9 63.2 60.6 54.5 41.1
1 of each
year
(i.e..
-
excluding
people
1920-1929
1930-1939
1940-1949
14.3 64.9 68.3 62.6 52.2 who started
-
-
15.1 59.8 61.2 55.9
13.8 59.8 57.3
or stopped
smoking
1950-1959
1960-1969
-
-
-
-
17.8 55.3
12.7
in that particular
year).
decline in prevalence became apparent (for instance, smoking prevalence at ages 30-39 declined from 68.3% in 1960 for the 1920- 1929 cohort to 57.3% in 1980 for the 1940- 1949 cohort). Smoking cessation increased between 1970 and 1980 among all age groups, including the youngest, thus superimposing a period effect on the obvious age effect in stopping smoking. As a consequence, the decline in prevalence was evident at a progressively earlier age in each successive cohort, and smoking rates among males born in 1940-1949 were already lower at ages 30-39 than at ages 20-29. The pattern for Italian females is quite different, since smoking was extremely uncommon among females at the beginning of the century, and smoking rates increased progressively among subsequent cohorts. Further, a period effect was superimposed on the age and cohort effects for starting smoking, so that smoking rates have tended to be higher at later and middle ages than at younger ages, contrary to the picture among males. For instance, the highest estimated prevalence for females born between 1900 and 1929 was registered between ages 50 and TABLE
3
ESTIMATEDPREVALENCE(%)OFCIGARE~ESMOKINGAMONGSUBSEQUENTBIRTHCOHORTSOF ITALIAN FEMALES,DERIVEDFROMTHECENTRALINSTITUTEOFSTATISTICS' 1983 NATIONALHEALTH SURVEY Birth cohort Calendar yeaP 1910 1920
1930 1940 1950 1960
1970 1980
1890-1899 0.2 1.6 2.4 2.6 2.4 2.0 1.5 1.1
1900-1909 0.3 2.5 3.8 4.5 4.5 4.1 3.0
1910-1919
1920-1929
-
-
0.9 5.1 7.2 7.8 8.3 6.8
1.0 8.0 11.3 12.1 12.5
1930-1939
1940-1949
-
a January 1 of each year (i.e.. excluding people who started or
1950-1959
1960-1969
1.7 11.4 15.7 17.4 stopped
-
2.3 20.3 25.2 smoking
5.9 32. I
in that particular
-
8.0 year).
610
LA
VECCHIA,
DECARLI,
AND
PAGAN0
59, and only after age 60 did subjects stopping smoking outnumber those starting. Consequently, age at starting smoking tends, on average, to be considerably later among female smokers. The continuous and progressive increase in smoking prevalence among women led to a substantial reduction of the male-to-female difference in smoking habits, from over 20-fold for the 1890-1899 cohort to about 37% for that born in 1960- 1969. We repeated similar analyses separately for the 14 Italian provinces including large urban concentrations (over 250,000 inhabitants in 1981) and for the remaining 81 provinces. Among males, estimated prevalences tended to be higher in those provinces that included urban concentrations for the younger age groups (ages 10 to 19), mostly in earlier cohorts (i.e., 12.8 vs 9.3% for the 1900-1909 cohort, 16.8 vs 15.0% for the 1910-1919 cohort), but little difference was observed in the subsequent age groups. Among females, striking differences were observed between urban concentrations and chiefly rural areas, since smoking diffusion was seen earlier in urban areas. Overall urban-rural differences were over 100% for the cohorts born before 1909, were over 50% for those born between 1910 and 1939, and tended to level off only in more recent generations. For instance, the highest estimated prevalences in provinces including urban concentrations were 7.6, 10.2, 17.1, and 21.5% for the 1900-1909, 1910-1919, 1920- 1929, and 1930- 1939 cohorts, respectively. Comparable figures for chiefly rural areas were 3.2, 6.7, 10.4, and 15.1%, respectively. DISCUSSION
According to the present analysis of data from the 1983 National Health Survey, the highest smoking prevalences among males were observed among the 1920-1929 generation, followed by moderate declines, chiefly on a calendar-period basis (i.e., between 1970 and 1980 in each birth cohort). Among females, cigarette smoking was extremely rare for generations born at the turn of the century (only about 3% of females born between 1890 and 1889 ever smoked), but increased in each birth cohort and calendar period to reach a rate only about one-third lower than that of males in the 1960- 1969 cohort. The prevalence rates presented are based on information collected in 1983 on a sample of live persons, and are therefore subject to several potential sources of bias. The problems are minor for more recent cohorts, since estimates are derived from large numbers and the effect of differential mortality of smokers and nonsmokers is negligible. The problems become progressively larger with earlier cohorts. Random variation, however, is still limited up to the 1900- 1909 cohort, at least among males (95% confidence intervals, based on the Poisson approximation, being around +3% of the rates presented for the 1900-1909 cohort). The major uncertainties relate to the 1890- 1899 cohort, since random variation is considerable (95% confidence intervals being around &20% of the rates in males), and the effect of correction for excess mortality among smokers is substantial (for instance, the crude prevalence of 40% in 1920 increased to 49% after correction). It is possible that these estimates are overcorrected, since we applied excess mor-
CIGARETTE
SMOKING
PREVALENCE
611
IN ITALY
tality ratios derived from British and American studies to an Italian population which smoked smaller numbers of cigarettes, at least at younger ages (12). Data on cohorts born after 1910 are more reliable, and estimates for younger males obtained by the present analysis appear to be in satisfactory agreement with a survey conducted in 1965 (5) by a private marketing research institute on a randomly selected sample of 6,095 subjects (Table 4). However, the 1965 smoking rate for males ages 45-54 derived from the 1983 NHS is lower than that obtained from contemporary interview data. This can be attributed to differences in sampling methods or to random variation (the 1965 Doxa survey was relatively small), but might also be due to a systematic tendency toward underreporting smoking over more recent periods (13), which may have led to anticipating the date of smoking cessation in some cases. With reference to a comparison with other Western countries (4, 7, 17), the Italian data show a delayed increase in smoking prevalence among males born at the turn of the century [mostly with respect to British data (4, 17)]. Also, the recent decline in smoking has been somewhat limited and has occurred later in Italy, where it was first observed among middle-aged males only during the 1970s. For females, the Italian pattern was largely different from that of most other Western countries (4, 7, 17), since smoking prevalence was markedly lower among Italian females born before the second world war. However, the increase among more recent cohorts has been extremely rapid, and smoking prevalence among younger Italian females in 1980 was not substantially different from that in other Western countries. Application of the present study to any interpretation of trends in mortality from tobacco-related diseases is not immediate, since an accurate measure of cigarette smoke exposure would reflect not only prevalence but also dosage of cigarette smoking. A few useful indications can nevertheless be derived from the present analysis. For instance, the observation that smoking prevalence was extremely low in the younger age groups among females born before the second world war compares well with the limited upward trends registered in mortality rates from lung and other tobacco-related neoplasms for the same cohorts of females (1, 14), since it is known that smoking habits in early life are a strong
TABLE 4 COMPARISON OF ESTIMATED PREVALENCES OF CIGARETTE SMOKING IN 1965 DERIVED FROM THE 1983 NATIONAL HEALTH SURVEY (NHS) WITH THOSE FROM A CONTEMPORARY MARKET SURVEY [DOXA, 1965; (5)] Estimated
prevalence
(7%) of cigarette
smoking
Males Age group
1983 NHS
25-34 35-44 45-54
60.5 66.4 58.6
a Excluding
“occasional”
smokers.
in 1965 Females
Doxa, 59.6 67.1 65.2
1965
1983 NHS 13.5 11.7 8.0
Doxa, 9.1 10.6 7.5
196.50
612
LA VECCHIA,
DECARLI,
AND PAGAN0
determinant of subsequent cancer risk (4). Among Italian males, lung cancer mortality increased markedly in each successive birth cohort from 1890 to 1930 and leveled off thereafter, up to a small decline for the 1950 cohort (1, 12, 14). This pattern, too, is in agreement with the evolving prevalence of cigarette smoking among subsequent birth cohorts. In conclusion, the present analysis of data from the 1983 National Health Survey shows considerable delays both in the spread of smoking among females and in the decline of smoking among males in Italy, compared with several other Western countries. These phenomena seem to be largely affected by cultural and economic factors, rather than by knowledge of the health consequences of smoking which has accumulated over the past three decades. Quantitative information on the health risks associated with smoking is therefore urgently needed to contrast, as much as possible, the delayed spread of the smoking-related disease epidemics in Italy, the consequences of which are already evident in national mortality data: For instance, Italian lung cancer death certification rates among young and middle-aged males are currently among the highest in any developed country (16). ACKNOWLEDGMENTS The contributions of the Italian Association for Cancer Research and of the Italian League against Tumors, Milan, Italy, are gratefully acknowledged. We thank Ms. Judy Baggott and Ms. Antonella Palmiero for editorial assistance.
REFERENCES 1. Decarli, A., La Vecchia, C., Cislaghi, C., Fasoli, M., Mezzanotte, G., and Negri, E. Cancer mortality in Italy, 1955- 1979: Effects of age, birth cohort and period of death. La mortalita per tumori in Italia: Effetti dell’eta, della generazione di nascita e del period0 di morte. Lega Italiana per la Lotta Contro i Tumori, Milano, (1986). 2. Doll, R., Gray, R., Hafner, B., and Peto, R. Mortality in relation to smoking: 22 years’ observations on female British doctors. Brit. Med. J. 280, 967-971 (1980). 3. Doll, R., and Peto, R. Mortality in relation to smoking: 20 years’ observations on male British doctors. Brit. Med. J. 2, 1525-1536 (1976). 4. Doll, R., and Peto, R. The causes of cancer: Quantitative estimates of avoidable risks of cancer in the United States today. J. Natl. Cancer Inst. 66, 1191- 1308 (1981). 5. Doxa. I fumatori in Italia. Una nuova indagine sui fumatori. Boll. Doxa 20, Nos. 20-21 (1966). 6. Hammond, E. C. Smoking in relation to the death rates of one million men and women. Natl. Cancer Inst. Monogr. 19, 127-204 (1966). 7. Harris, J. E. Cigarette smoking among successive birth cohorts of men and women in the United States during 1900-80. J. Natl. Cancer Inst. 71, 473-479 (1983). 8. Istituto Centrale di Statistica (ISTAT). Andamento demografico e sanitario. Notiziario ISTAT 5, Nos. 9-11 (1984). 9. Istituto Centrale di Statistica. Indagine statistica sulle condizioni di salute della popolazione e sul ricorso ai servizi sanitari-1983. Primi risultati. Notiziario ISTAT 4, No. 8 (1984). IO. Istituto Centrale di Statistica. Tavole di mortalita della popolazione Italiana per regione. 1977-79. Boll. Mensile Statist. 16 (Suppl.) (1983). 11. Kahn, H. A. The Dorn study of smoking and mortality among U.S. veterans: Report on eight and one-half years of observations. Nat/. Cancer Inst. Monogr. 19, 1-125 (1966). 12. La Vecchia, C. Patterns of cigarette smoking and trends in lung cancer mortality in Italy. J. Epidemiol. Community Health 39, 157-164 (1985). 13. La Vecchia, C. Smoking in Italy, 1949-1983. Prev. Med. 15, 274-281 (1986).
CIGARETTE
SMOKING
PREVALENCE
IN ITALY
613
14. La Vecchia, C., and Decarli, A. Trends in cancer mortality in Italy, 1955- 1978. Tumori 71, 201-218 (1985). 15. La Vecchia, C., and Decarli, A. Trends in ischemic heart disease mortality in Italy 1968-1978. Amer.
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76, 454-456
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(1984). 17.
Office of Population, Censuses and Surveys. Cigarette smoking: 1972 to 1982. OPCS Moniror, 5 July (1983).