Bull Pan Am Health Organ la(l). 1984.

AN EPIDEMIOLOGIC SURVEY OF SMOKING PATTERNS AND CHRONIC OBSTRUCTIVE BRONCHOPULMONARY DISEASE IN P6RTO ALEGRE, BRAZIL1

J. A. Chaieb,z D. Vitola,3 M. S. Silva,3 N. Clausell,3 F. S. Neff,3 and H. Levin3

To help assess the progress of a local anti-smoking campaign and also to learn more about patterns of tobacco use and obstructive respirato;ry disease in Brazil, a survey of smoking habits, obstructive lung disease, and lung function was conducted in the city of P&to Alegre in 1980. This article reports the results of that survey.

Introduction

Faced with a scarcity of national statistical data on smoking and chronic obstructive bronchopulmonary disease, we have felt a need to study the subject, using international- ly accepted research standards, for the pur- pose of better understanding the epidemiology of this type of disease in Brazil.

Smoking is known to be responsible for a wide variety of disorders, the incidences of which have tended to increase in direct pro- portion to the percentage of smokers. In this vein, cigarette consumption has risen sharply over the course of this century. In Great Brit- ain, for example, the consumption figures cited by Wald rose from 2,000 cigarettes a year for each male smoker in 1922 to 4,000 in 1975. During the same period, the average number of cigarettes consumed by female smokers in Great Britain rose from practically zero to 2,500 per year (I).

Worldwide, the increased consumption of cigarettes has been paralleled by an upturn in the recorded mortality from respiratory dis-

‘Also appearing in Portuguese in the Boletin de la Ofi- &a Sanitaria Panamericana 96(2), 1984.

2Professor of Pneumology, Pontifical Catholic Uni- versity, Medical School of PBrto Alegre, Pbrto Alegre, Brazil.

3Medical students, Pontifical Catholic University, Medical School of P&to Alegre, Brazil.

eases-particularly chronic bronchitis, em- physema, and lung cancer. The fact that such mortality has increased in direct proportion to the rate of cigarette consumption has been substantiated by a collection of studies re- cently published by the World Health Orga- nization (2). In addition, countless prospec- tive and retrospective studies bear witness to the link between smoking and impaired lung function, while other studies attest to the fact that this functional damage is at least partially reversible if the smoking habit is broken.

Evaluations have also been performed re- garding the role of chronic coughing and ex- pectoration as antecedents of pulmonary dis- ease in infancy and as factors predisposing subjects to a loss of pulmonary function. Some studies support while others oppose the theory that these factors play a role in the genesis of impaired pulmonary function.

In order to more specifically and precisely evaluate not only the degree of possible im- pairment but also abnormalities that might re- main undetected by less sensitive methods, a number of tests have been developed. These include tests of peak expiratory flow (PF), residual volume or residual capacity (RC), one-second forced expiratory volume (FEVl), the latter volume divided by the forced vital capacity, maximal voluntary ventilation (MVV), the mean forced expiratory flow be- tween 25 and 75 per cent of the forced vital

26

Chaieb et al. l SMOKING PAmERNS IN P6RTO ALEGRJX 27

capacity, the maximum expiratory flow (Vmax) at 25 and 50 per cent of vital capacity, and the diffusing capacity for CO (DCO). Re- search efforts utilizing these various tests have provided strong confirmation of the following

hypotheses:

1) Prolonged inhalation of tobacco smoke leads to impaired respiratory function.

2) The extent of impairment is related to the number of cigarettes smoked.

3) Exposure to smoke causes hypersecretion and coughing; these latter symptoms are not directly re- lated to impaired pulmonary function and are re- versible if the subject stops smoking. However, they also predispose the bronchial tree to damage by infectious agents.

4) Cessation of smoking leads to at least partial improvement of the functional damage.

The purpose of the study reported here was not only to make an original contribution to this subject but also to answer a number of basic epidemiologic questions relevant to the Brazilian context. There is a lack of epidemi- ologic data on obstructive respiratory diseases in Brazil, and until now we have tended to ig- nore how people have responded to anti-smok- ing campaigns. The need to acquire expertise in planning and executing surveys in this field, and to overcome the inherent difficulties involved, was the challenge that prompted us to seek answers to the following questions as they apply to P&to Alegre:

1) How many smokers and former smokers are there in the adult population?

2) How many people over 35 years of age experi- ence symptoms of coughing and expectoration?

3) What is the peak expiratory flow level of smokers and nonsmokers over 35 years of age?

4) How do these data correlate by sex and age group?

5) What estimates can be made regarding the ex- tent of the smoking habit and its relationship to the peak expiratory flow?

In 1980 the basis for an anti-smoking cam- paign was established by an agreement be- tween the Medical Association of Rio Grande do Sul, the state department of education, and the state health department. This agreement covered not only collection of funds for the campaign but also the publicity methods to be

employed, use of the mass media, production and distribution of posters, other forms of ad- vertising, and so forth. The groups involved also prompted the Government to implement laws that banned smoking on general trans- port vehicles, in shops, and in public places. This campaign was a relevant background factor in P&-to Alegre at the time of our study. However, it should be noted that our study was an entirely independent undertaking hav- ing no connection whatever with this anti- smoking effort.

Materials and Methods

The Study Art-a

Figure 1 shows the area of P&to Alegre se- lected for the survey-the quadrangle defined by the black lines with its narrow end at the center of the city and its wider end in the city’s outskirts. This area met the following criteria: (1) it was a relatively pollution-free and prin- cipally residential cross-section of P&-to Ale- gre; (2) it included a reasonable sample of smokers and former smokers from various so- cioeconomic strata; and (3) it did not include business districts.

The Study Population

The population selected for the study in- cluded people over 35 years of age residing in the study area. It was assumed that this group would be more likely than younger groups to show the possible effects of chronic smoking.

The number of study subjects to be inter- viewed was then narrowed down by selecting 60 streets within the study area at random. One thousand homes on those streets were then visited, and interview information was gathered on the 418 people-smokers and former smokers of both sexes-who were pres- ent at the time of the interviewer’s visit. Inter- view information was also gathered from a control group- 122 nonsmokers of both sexes who were living in the same area.

Figure I. A map of P&to Alegre, Brazil, showing the area surveyed and its three major subdivisions.

Chaieb et al. l SMOKING PATTERNS IN PeRTO ALEGRE 29

Field Activities

The period from February to April 1980 (a period of stable climate) was selected for the field work.

The home visits and interviews were con- ducted by a team of medical students trained expressly for this purpose and equipped with questionnaires, a measuring tape, and a Mini- Wright Peak Flow Meter.

The interview subjects’ homes were visited on weekday afternoons after 5 p.m. and on weekends in the morning. This was done in order to arrive when the greatest number of adults were apt to be at home. The question- naire was a simplified version of the one pro- posed by the British Medical Research Coun- cil in 1960, adapted to the special circum- stances and customs of our population.

The interviews and accompanying mea- surements were carried out by two-man teams. After the team members had formally introduced themselves and the subject had agreed to be interviewed, a questionnaire was completed. The procedure for taking the de- sired measurements was then demonstrated, the subject’s height was recorded, three peak expiratory flow readings (measured in liters per minute) were taken, and the best one of these readings was recorded (3).

Thereafter, an expected peak flow value was computed on the basis of each subject’s height, age, and sex, using the table devised by Gregg and Nunn (4). The percentage flow observed vis-a-vis the predicted value was then used as an indicator of pulmonary func- tion, employing the formula

Flow recorded x loo

Flow predicted

to obtain the appropriate percentage value for each subject.

The Questionnaire

After requesting generic information re- lating to family members (such as the number

of family members under and over 35 years of age and the number of smokers under and over 35), those over 35 years of age who were present at the time of the visit and who agreed to be interviewed were asked the following questions:

1) Have you ever had, or do you have, any lung disease?

2) Have you ever had, or do you have, bronchial asthma?

3) At what age did you start to smoke? 4) At what age did you stop smoking? 5) How many cigarettes do you smoke per day? 6) Have you had a frequent cough for more than

two years? 7) Have you had a catarrhaf discharge for more

than two years? 8) What is your personal income?

Questions 3, 4, and 5 were omitted in the case of nonsmokers. No queries relative to other forms of smoking were included, since pipes and cigars are rarely used in Brazil.

For the purposes of this survey the following definitions were employed: A nonsmoker was defined as someone who did not smoke even one cigarette per day; a smoker was defined as someone who regularly smoked at least one cigarette per day; and a former smoker was defined as someone who had given up the habit for at least a year at the time of the survey.

The team of interviewers was prepared to provide any information needed by the inter- view subjects regarding lung diseases or asthma. This information, given in plain (col- loquial) language, included the signs and symptoms of these ailments.

Questions 1 and 2 were included with the aim of studying flow variations due to ana- tomic and functional lung impairments caused by diseases such as tuberculosis, pneumonia, pleurisy, and mycoses. These would clearly constitute a new set of factors-to be consid- ered among other factors that reduce flow- and would be noteworthy primarily in areas where the prevalence of such diseases is rela- tively great.

30 PAHO BULLETIN l vol. 18, no. I, 1984

Data Analysis

The information obtained using these ques- tionnaires was subsequently codified, trans- ferred onto cards, and submitted to the SPSS4 program for entry into the Catholic Universi- ty computer. The resulting data were subse- quently reevaluated for purposes of analysis and presentation.

Student’s t test was used to compare the average heights and ages of smokers, former smokers, and nonsmokers of both sexes in order to determine whether there were signifi- cant differences in these average heights or ages (see Table 3). Also, as shown in Tables 4 and 5, the chi-square test was used to examine data on subjects with or without lung disease or asthma by age and sex.

Relationships between the degree to which expected peak flow values were attained and smoking habits in both sexes were scrutinized using Student’s t test, as shown in Tables 8 and 9; and the same test was used to examine the relationships shown in Figures 2 through 7.

The existence of a possible correlation be- tween the degree to which expected flow val- ues were attained and smoking status-among groups of subjects with and without symptoms of coughing and sputum-was analyzed by means of the chi-square test (Table 10).

Results

As previously noted, the survey began in February 1980 and was completed in April of that year. The survey area took in all or part of nine distinct neighborhoods belonging es- sentially to three socioeconomic strata. The outermost district (area 1) contained the pop- ulation with the lowest socioeconomic status, the average income of survey subjects in this area being 2.4 times the then current mini- mum pay (2,760 cruzeiros per month). The middle district (area 2) contained the popula- tion with the highest socioeconomic status, the average income being some eight times the

4Statistical Package for the Social Sciences.

minimum pay. And the innermost district (area 3), in the central part of the city, con- tained a population with an intermediate so- cioeconomic status, the average income being five times the minimum pay.

General discussion of the interview sub- jects’ smoking habits was used to learn when they began smoking. These discussions re- vealed that the largest percentage had begun to smoke between the ages of 10 and 15, and that 50 per cent of the smokers acquired the habit before age 15. Overall, only 17 per cent of the smokers had begun to smoke after reaching 20 years of age.

Only 6 per cent of the former smokers stop- ped smoking before they were 35. However, the cessation rates were quite uniform be- tween the ages of 35 and 55, with about 14.5 per cent of the former smokers giving up the habit in each five-year portion of this age range. Thereafter the cessation rate subsided again- to a level of some 8.8 per cent for sub- sequent five-year periods. Overall, those who managed to give up the habit had smoked for an average of 30 years.

The average number of cigarettes smoked by the survey subjects was also recorded. Ac- cording to these data, 36 per cent of the smok- ers reported averaging 20 cigarettes a day and 53 per cent (including the aforementioned 36) reported averaging between 20 and 30 a day. The overall daily average was 2 1.

Table 1 shows the distribution by sex of the smokers and former smokers in the sample. This brings out the fact that considering smokers and former smokers together, a high- er percentage of the males had given up the habit. That is, male former smokers accounted for 27.6 per cent of the male smokers and former smokers, while female former smokers accounted for only 16.9 per cent. The ratio between these male and female percentages is 1.6 to 1.

Data relating to the number of smokers and former smokers in the different residential areas covered by the survey are shown in Ta- ble 2. Comparison of these various figures in- dicates that the ratio of former smokers to

Chaieb et al. l SMOKING PATTERNS IN PbRTO ALEGRE 31

Table 1. Distribution of smokers and former smokers in the survey population, by sex.

Met3

Women

Total

Smokers Former smokers Total

NO. % No. % NO. %

213 72.4 81 27.6 294 100

103 83.1 21 16.9 124 100

316 75.6 102 24.4 418 100

Table 2. Ratio of former smokers to smokers in the three major survey areas shown in Figure 1.

survey area Men

Smokers

WOIIKII Total

Former smoker: Former smokers smoker ratio

Men WOllle~ Total MelI WOIIXII

1 87 50 137 13 4 17 1:6.7 1:12.5

2 82 30 112 38 9 47 1:2.2 1: 3.3

3 44 23 67 30 8 38 1:1.5 1: 2.9

Total 213 103 316 81 21 102 1:2.6 1: 4.9

smokers was lowest in the poorest region (area l), suggesting that members of the lowest so- cioeconomic stratum had the least success in giving up the habit. These figures could also serve as an indication that people in the upper and middle socioeconomic strata may respond better to educational campaigns against smok- ing.

As previously noted, the survey also mea- sured the peak flow values of the 540 interview subjects. Since these peak flow values vary

with the age, sex, and height of the subject, and since we wished to express the values re- corded as a percentage of the expected value, it was important to consider the sex, age, and height of smokers, former smokers, and non- smokers in the survey population.

A comparison of the average ages and heights of men and women in the survey population, by smoking category, is shown in Table 3. The difference between the heights of men and women in each smoking category re-

Table 3. Average ages and heights of survey subjects, showing standard deviations, by smoking status and sex.a

Smokers

Former smokers

Nonsmokers (controls)

Total

Men Women

Average age Average heqht (years) f 1

No. of (cm) f 1

Average age Average height (cm) f 1

standard standard (years) i 1

No. of standard standard Total no. subjects deviation deviation subjects deviation deviation of subjects

213 49.2 f 10.9 (a) 169.8 f 6.53 103 46.7 f 12.1 (d) 159.3 f 5.9 316

81 55.7 f 11.3 (b) 169.9 f 7.08 21 55.5 f 12.6 (e) 159.5 f 5.5 102

56 51.2 f 13.3 (c) 171.2 k6.1 66 50.6* 11.5 (r) 161.0 f 5.2 122

350 190 540

?%atistical significance of differences between pairs of figures in columns: a-b, p<O.Oi; b-c, ~~0.05; a-c, NS (difference not sigmficant); d-e, p<O.Ol; e-f, NS; d-f, p<O.O5; differences between pairs of figures in other columns are not significant.

32 PAHO BULLETIN l vol. I8> no. 1, 1984

fleets the normal variation between the sexes. There was no statistically significant sex-re- lated difference in the average ages of males and females in any of the specified smoking and control categories; nor was there any significant difference in the height of males or females in different smoking categories.

The same cannot be said, however, about the average ages of subjects in the different smoking categories; that is, the average age of male former smokers was significantly higher than the average age of male smokers (p<O.OOl) and was also significantly higher than the average age of male nonsmokers (p < 0.05). In a similar vein, the average age of female smokers was significantly less than the average age of female former smokers (pCO.01) and the average age of female non- smokers (~~0.05). Such variations in age- one of the factors affecting peak expiratory flow values-helps to explain why it was felt desirable not to express those values directly, but rather to express them as a percentage of the value expected for each subject.

Usually such expected peak flow values are obtained by applying a linear regression equa- tion to a representative population considered normal in terms of pulmonary ventilation. However, we did not select a normal control population of this kind for our survey, and so we decided instead to compare the actual fig- ures with the aforementioned figures provided by Gregg and Nunn (4).

In addition to examining the effects of smoking, one of our objectives was to obtain data on the presence of diseases or conditions other than smoking that could affect the peak expiratory flow values of epidemiologic survey populations. The answers to our simple ques- tionnaire (see Figure 2) revealed that subjects who reported past or present pulmonary dis- ease (tuberculosis, pneumonia, or pleurisy) or asthma had significantly lower peak expirato- ry flows, on the average, than those who did not (p<O.Ol).

When the distribution of those reporting such disorders, grouped by smoking habits, was evaluated bv the chi-sauare test (Tables 4

Figure 2. Percentages of expected peak expira- tory flow values attained by survey subjects reporting current or prior asthma, lung disease, or neither of these problems. The lung diseases considered were tuberculosis, pleurisy, and

pneumonia. The line at the top of each bar represents one standard deviation

from the mean.

loo-

2 s so-

e

I

01 D A N

D= SUBJECTS REPORTING LUNG DISEASE

A= SUBJECTS REPORTING ASTHMA

N= NORMAL SUBJECTS

D-N,P < 0.01 A-N,P < 0.01 D-A,NS

and 5), no statistically significant differences emerged between the prevalences of lung dis- ease among smokers, former smokers, and nonsmokers, or between the prevalences of asthma within these same groups. These find- ings demonstrate a happenstance distribution of individuals with asthma or lung diseases, present or past, among the survey smokers, former smokers, and nonsmokers-indicating that these conditions did not significantly in- fluence the differences in peak expiratory flows found among these three grottos. Also. when

Table 4. Distribution of survey subjects with and without a history of lung disease (tuberculosis, pleurisy, or pneumonia) by smoking status and s~x.~

Smokers Former smokers Nonsmokers Total

Men Women (d) Total (a) MelI Women Total (b) Men Women (e) Total (c) Men Women Total

No. % No. % No. % No. % No. % No. % No. % No. % No. % No. % No. % No. %

With lung diseaseb 24 11.3 4 3.9 28 8.9 8 9.9 2 9.5 10 9.8 I 12.5 9 13.6 16 13.1 39 11.1 15 7.9 54 10.0

Without lung disease 189 88.7 99 96.1 288 91.1 73 90.1 19 90.5 92 90.2 49 87.5 57 86.4 106 86.9 311 88.9 175 92.1 486 90.0

Total 213 100 103 100 316 100 81 100 21 100 102 100 56 100 66 100 122 100 350 100 190 100 540 100

aDifferences between figures a and b, b and c, and a and c, were not statistically significant. For the difference between d and e, p~O.01. bsubjects who repotted having a current OF prior case of tuberculosis, pleurisy, or pneumonia.

Table 5. Distribution of survey subjects with and without a history of asthma, by smoking status and se~,~

Smokers Former smokers Nonsmokers Total

MelI Women Total (a) Men Women Total (b) MetI WOtP3l Total (c) Men (d) Women (e) Total ---~-- ~-~--

No. % No. % No. % No. % No. % No. % No. % No. % No. % No. % No. % No. %

With asthmab 5 2.3 10 9.7 15 4.7 3 3.7 2 9.5 5 4.9 1 1.8 2 3.0 3 2.5 9 2.6 14 7.4 23 4.3

Without asthma 208 97.7 93 90.3 301 95.3 78 96.3 19 90.5 97 95.1 55 98.2 64 97.0 119 97.5 341 97.5 176 92.6 517 95.7

Total 213 100 103 100 316 100 81 100 21 100 102 100 56 100 66 100 122 100 350 100 190 100 540 100

aDifferences between figures a and b, b and c, and a and c were not statistically sigmficant. For the difference between d and e, pCO.01. bsubjects who reported having current or prior asthma.

34 PAHO BULLETIN l vol. 18, no. 1, 1984

sex was considered the only correlations found were a relatively higher prevalence of lung disease among nonsmoking females (p < 0.01) and a lower prevalence of asthma among men than among women (p<O.Ol).

Tables 6 and 7 show the average peak ex- piratory flow values obtained for the survey men and women in the smoking, former smoking, and nonsmoking groups, along with the corresponding standard deviations. Figure 3 expresses these same survey values as per-

Table 6. Average peak expiratory flow values for men in the survey population, showing one standard

deviation, by smoking status.

GrOUtI No. of

Average peak expiratoty flow, with standard devia-

men tion. in liters per minute - Smokers

Former smokers

Nonsmokers (controls)

Total

213 505.56 * 105.17

81 525.74 f 113.34

56 548.30 f 110.76

350 517.07 f 108.86

Table 7. Average peak expiratory flow values for women in the study population, showing one standard

deviation, by smoking status.

Group

Smokers

Former smokers

Nonsmokers (controls)

Total

Average peak expiratory No of ilow, with standard devia- women tmn, in liters per minute

103 378.59 * 80.87

21 411.43 k95.62

66 413.48 * 60.75

190 394.34 f 77.86

centages of the average values expected for each group. Analysis of these data shows a sig- nificant difference between the smokers and nonsmokers of both sexes (p<O.OOl), the values for smokers being lower in both cases. Also, the average value obtained by male former smokers was significantly greater than that obtained by male smokers (p<O.O5); however, the difference in the values obtained by female smokers and former smokers was not statistically significant, probably because

Figure 3. Percentages of expected peak expiratory flow values attained by smokers (S), former smokers (EX), and nonsmokers (N)

in the survey population, by sex.

0 s EX N s EX N

MEN

S-N, P < 0.001 S-EX, P < 0.05

WOMEN

S-N, P < 0.001

Chaieb et al. l SMOKING PA?TERNS IN P6RTO ALEGRE 35

of the small number of former smokers in- volved. The lack of any major difference be- tween the average rates obtained by non- smokers and former smokers suggests that those who stop smoking recover the pulmo- nary capacity lost when they smoked, at least to some degree.

We also sought to determine what Deeley and Cohen (5) call the “tobacco factor” or tobacco index, this being the average number of cigarettes smoked daily times the number of years the smoker has had the habit, and to compare this index with the percentage of ex- pected peak expiratory flow values attained by the survey subjects. Tables 8 and 9 make this comparison for men and women, respectively. The comparison shows a marked difference between the percentage of expected values at-

Table 8. Relationships between the smoking index (No. of cigarettes smoked daily x No. of years smoking)

and the % of the expected peak expiratory flow value attained by male subjects.

% of expected No. of peak expiratory One standard

Smoking index= men value attained deviation (%)

0 (4 56 93.52 * 11.51 l-500 (b) 93 87.39 * 15.31

501-1,000 (c) 141 86.31 f 16.81 > 1,000 (d) 60 83.57 f 20.31

Total 350 87.28 * 16.54

‘Statistical significance of a-b: p<O.Ol; b-c and c-d not sta- tistically significant.

Table 9. Relationships between the smoking index (No. of cigarettes smoked daily x No. of years smoking)

and the % of the expected peak expiratory value attained by female subjects.

% of expected No. of peak expiratory One standard

Smoking indexa women value attained deviation (%)

0 (4 66 91.09 * 12.13 l-500 (b) 80 83.84 * 16.01

501-1,000 (c) 36 84.75 * 15.10

> 1,000 (d) 8 65.12 * 25.18

Total 190 85.74 * 15.91

‘Statistical significance of differences between figures: a-b, p<O.Ol; b-c not sqnificant; c-d, p<O.O5.

tamed by nonsmokers and those attained by smokers in all the “tobacco index” categories, as was to have been expected. In addition, it shows that women with a tobacco index over 1,000 had a significantly lower peak expirato- ry flow score than women with lower smoking indexes (p<O.O5), suggesting a direct correla- tion between the index and reduced peak ex- piratory flow among women. However, the limited survey data did not demonstrate a parallel correlation among men.

l%gures 4 and 5 show the peak expiratory flow values, as percentages of the expected values, for smokers, former smokers, and nonsmokers of both sexes broken down by age groups (35-44, 45-54, 55-64, and over 65). Among the men, smokers attained significant- ly poorer average values than nonsmokers in all age groups. The average values attained by male former smokers in the 35 to 44 age group were also considerably below those of the non- smokers, but there was little difference be- tween the average values for former smokers and nonsmokers in the 45-54 and 55-64 age groups. Female smokers also made a poorer showing than nonsmokers, although the ob- served difference was statistically significant only in the 45-54 and 55-64 age groups. Also, the female former smokers’ average values were close to those of the nonsmokers; a sta- tistically significant difference between female smokers and former smokers was found only in the 35-44 age group.

A different projection of these data is pro- vided in Figures 6 and 7, which show the ab- solute peak expiratory values obtained to- gether with the absolute values expected for each age group in order to provide projections comparable to those provided by Gregg and Nunn (a).

The “expected’ ’ values were derived by taking the average heights of our male and female subjects (1.70 and 1.60 meters, respec- tively) and looking up the values expected for each age group of the appropriate height and sex. This made it possible to compare the values obtained by our nonsmoking control population with the expected values.

36 PAHO BULLETIN . vol, 18, no. I, 1984

Figure 4. Data for men; percentages of expected peak expiratory flow values attained by male smokers (S), former smokers (EX), and nonsmokers (N)

in the survey population, by age group.

100

2 5 50

P UI P

0 S EX N S EX N S EX N S EXN

33-44 YEARS 45-54 YEARS 55-64 YEARS z 65 YEARS

S-N,P < 0.05 S-N,P < 0.05 S-N,P < 0.05 S-N,P < 0.05

EX-N,P < 0.05 S-EX,P < 0.01 S-EX,P 4 0.05

These charts show a clear difference be- of all age groups were below the expected tween the values expected on the basis of the average values for each sex. Gregg and Nunn figures and those obtained In addition, there was a statistically signif- by the nonsmoking control group. That is, icant decline in the average values for male even though the general trends observed were smokers (p<O.Ol) and male former smokers fairly similar to those expected, the average (p < 0.05) in the over 65 age group vis-a-vis the values found for nonsmoking men and women average values for those in the 55-64 age

Figure 5. Data for women; percentages of expected peak expiratory flow values attained by female smokers (S), former smokers (EX), and nonsmokers (N)

in the survey population, by age group.

S EX N S EX N S EX N S EX N

33-44 YEARS 45-54 YEARS 55-64 YEARS 2 65 YEARS

S-EX, P<O.OS S-N,P<O.OS S-N, PdO.01

Chaieb et al. l SMOKING PATTERNS IN PORT0 ALEGRE 37

Figure 6. Data for men; a comparison of expected peak expiratory flow values for men and the actual values attained by surveyed male smokers,

former smokers, and nonsmokers in different age groups.

630

610

590

570

550

530

510

490

470

450

430

410

390

370

‘t ‘t -\ -\ ,,A- EXPECTED ,,A- EXPECTED

‘+ ‘+ \ \

- CONTROLS - CONTROLS ‘+ ‘+

\ \ \ \

-1-11 FORMER SMOKERS -1-11 FORMER SMOKERS \ \

.--m-m SMOKERS .--m-m SMOKERS ‘\ ‘\ \ \

‘I ‘I \ \

‘+ ‘+

I I I I

35-44 45-54 55-64 265

MALE AGE GROUPS ( IN YEARS )

group. (This apparent increased drop in the average expiratory flow values for male former smokers could reflect a situation where older smokers abandoned the habit after suffering marked loss of pulmonary function.) The sig- nificance of this decline could not be evaluated with the same degree of assurance for the fe- male study population, because of the small numbers of subjects involved; however, marked declines in the average values for fe- male smokers and former smokers were ob- served in the 45-54 and 55-64 age groups (p<O.O5).

We also looked for correlations between certain symptoms (persistence of cough and sputum for more than two years) and the per- centages of peak expiratory values attained. The data involved are shown in Table 10. As the table indicates, we were unable to detect

any significant relationship between the pres- ence of cough and sputum for that length of time and loss of pulmonary function.

Discussion

This study was founded on the premise that since the State of Rio Grande do Sul, and es- pecially its capital, P&-to Alegre, are involved in an intense anti-smoking campaign, it would be useful to explore the P&to Alegre popula- tion’s smoking patterns following initiation of that campaign. The survey conducted could then be repeated later, using the same tech- nique, covering the same 60 streets, and seek- ing to include the same homes and families surveyed. The reason this survey seemed ap- propriate is that even though research in other countries had amply revealed smoking’s dele-

38 PAHO BULLETIN l vol. 18, no. I, 1984

Figure 7. Data for women; a comparison of expected peak expiratory flow values for women and the actual values attained by surveyed female smokers,

former smokers, and nonsmokers in different age groups.

500

480

460

440

420

4oa

38C

36C

34(

32(

30(

28C

-1///11 EXPECTED ‘,

.a----. FORMER SMOKERS

n ----= SMOKERS

I I I I 35-44 45-54 55-64 z65

FEMALE AGE GROUPS (IN YEARS)

Table 10. Relationships between obstructive symptoms (coughing and sputum) and the % of the expected peak expiratory flow values attained, by smoking status.a

Group

Symptoms (cough- ing and sputum)

Present

Absent

Smokers (a)

% of expected No. of Pefor;$iteory

subjects attained

125 82.1

191 84.2

Former smokers (b)

% of expected No. of peak expiratory

subjects flow value attained

14 84.4

88 90.9

Nonsmokers (c)

% of expected No. of

subjects P”$o;tp”r’y

attained

1 91.0

121 92.2

aDifferences between ‘70 of expected peak expiratmy flow values attained (a-b, b-c, a-c) not statistically significant.

terious effects, it was felt important to use available techniques (including the same tech- niques already employed elsewhere) to deter- mine what was happening within our own population.

Since the present survey included different socioeconomic strata, it was also felt impor- tant to determine how these different strata

had responded to the anti-smoking effort. Table 2 examines the proportions of both males and females who reported that they had given up the habit. This proportiofl of former smokers to current and former smokers (27.6 per cent among men, 16.9 per cent among women) was much higher among men than among women, yielding a male:female ratio

Chieb et al. l SMOKING PATTERNS IN P6RTO ALEGRE 39

similar to that reported by Fry (S). There appear to be two possible explanations for this phenomenon, these being (1) that the male smoking population was more responsive to the anti-smoking campaign or more inclined to give up smoking than was the female popu- lation (Russell, et al. (7) assert that women find it harder than men to give up smoking); or (2) that the women were less subject to the harmful effects of smoking.

Regarding socioeconomic status, Table 2 also shows the proportions of smokers and for- mer smokers who said they had given up smoking in each of the three geographic areas surveyed. For both sexes, the proportion of those giving up smoking rose as one approach- ed the city center. This finding suggests that living in a city center that is the seat of an in- tense anti-smoking campaign could have more impact upon people’s tendency to stop smok- ing than does their socioeconomic status. It was also observed that the lowest rates of giv- ing up smoking among both men and women were found in the outermost area, where the residents were farthest from the city center and also had the lowest average socioeconomic status.

Tables 4 and 5 compare male and female subjects’ histories of asthma and lung disease (tuberculosis, pleurisy, or pneumonia) with their smoking habits. In all, 10 per cent of the survey population (54 people) reported ex- periencing one of these lung diseases and 4.3 per cent (23 people) reported experiencing asthma.

This 10 per cent lung disease figure appears acceptable, because it represents a cumulative prevalence in a group of subjects ranging from 35 to over 80 years of age. It is true that the number of abnormal X-rays is generally less than 2 per cent (8). However, it is also possi- ble for many respiratory tract infections to escape radiologic detection but nevertheless leave functional sequelae. Such a situation is suggested in our survey population by the fact that those reporting current or prior lung dis- ease had significantly lower peak expiratory flow values than those who said they had not had such disorders (~~0.01, see Figure 1).

As noted earlier (see Table 4), no statistical- ly significant difference was found between subjects reporting lung disease and the rest of the survey population with regard to smoking patterns, so long as the sexes were combined. However, there did appear to be a significant- ly higher prevalence (p<O.Ol) of pulmonary disorders among women nonsmokers. The reason for this phenomenon is unclear, so it is appropriate merely to observe that women in our sample who reported past or current lung disease appeared less apt to smoke than other women.

The prevalence of asthma (past or present) in our sample was 4.3 per cent. This figure is compatible with the range of prevalences reported in the literature-prevalences which vary from 1 to 10 per cent (9). There was little difference between those who reported asthma and those who did not, insofar as smoking habits were concerned. However, the break- down by sex showed a clearly higher preva- lence (p< 0.01) of asthma among women. This finding agrees with a number of epidemiologic studies that have demonstrated a relatively high prevalence of asthma within the adult female population (9).

Overall, we feel that the information re- vealed by answers to the questions asked about asthma and lung disease was both co- herent and useful, an opinion that has been expressed by other authors (IO).

Like other studies (11-X.5), ours surveyed the effects of smoking on the rate of expiratory flow in terms of peak values; and like others we found that smokers had lower average peak values than nonsmokers (see Figure 3). We were also able to show that former smokers’ average values did not differ significantly from those of nonsmokers-an important point reinforcing previous findings (2, II, 15) that indicate the functional damage caused by smoking is at least partially reversible.

The peak expiratory flow values for the various age groups (see Figures 6 and 7) show that the average peak values decline with age. This is shown by the downward-sloping lines obtained for the control group in our study, and more generally by the negative slope of

40 PAHO BULLETIN l vol. 18, no. 1, 1984

“expected” values derived from the Gregg and Nunn figures (4). In this regard, some authors say it is normal for peak expiratory flow values and expiration volume to decline with age, and some go so far as to estimate the expected reduction in terms of age (16,17). Others, who have measured declines by age for smokers and nonsmokers (17-19), hold smoking responsible for an excess decline in the one-second forced expiratory volume (FEVI) that shows up when the values for smokers and nonsmokers in various age groups are compared (ll,l7). And still other researchers, using more sensitive techniques, have been able to demonstrate an “excess” decline in expiratory flow values among smokers over a relatively short period of time

w9 Although our study was not longitudinal in

nature, a glance at the expiratory flow curves obtained for smokers and nonsmoking control subjects in Figures 6 and 7 makes it clear that the smokers experienced considerably more loss of peak expiratory flow values over a pe- riod of years than did the nonsmokers. How- ever, the female population in our study ex- perienced considerably greater average losses (~~0.05) between 45 and 64 years of age, whereas within the male population this de- cline was more pronounced after age 55 (pCO.01).

A longitudinal study by Bosse, et al. showed a particularly sharp decline among smokers 45-54 years of age, and another (nonlongitu- dinal) study showed the same thing for those above age 50 (11,21). These studies, as well as our own, lead to the conclusion that the de- cline in peak expiratory flow values observed after age 50 among smokers-and even among former smokers-appears much more pronounced than in other age groups and could signify an increase in respiratory dis- tress and premature disability.

Our survey found no clear correlation be- tween the number of cigarettes smoked, ex- pressed as a smoking index, and reduced peak expiratory values for the two sexes combined; but it did find such a correlation among female subjects (see Tables 8 and 9). Such a progres-

sive correlation has been found by some re- search studies (I.?, 14,16, Zl), but not by others (15,22).

As Table 10 shows, there is an obvious association between the presence of certain physical symptoms (coughing and sputum) and smoking; however, no statistically signifi- cant correlation could be found between the presence of these symptoms and reduced peak expiratory flow values. The literature on this subject cites some cases where an association between these symptoms and loss of pulmo- nary function was found (12,22,23) and other cases where it was not (24-26).

The best explanation for this dichotomy may be that chronic cough and sputum appear very early in the natural history of obstructive disease, and so these symptoms must persist for many years before functional changes oc- cur that can be detected by such gross evalua- tion methods as the peak expiratory flow or even one-second forced expiratory volume measurements.

Some researchers (17,18) have found that the annual decline in one-second forced vital capacity in the smoking population is approx- imately 56 ml per year. At this rate, they es- timate that 20 to 30 years of smoking must elapse before sufficient obstruction occurs to produce clinically significant dyspnea. Our study found that most of the survey subjects who smoked started doing so before they were 16, and that only 17 per cent waited until they reached the age of 20. Moreover, those who gave up the habit had smoked an average of 30 years, and the average age of former smok- ers in the survey population was 56 f 11 years. These data have led us to tentatively conclude that cessation of smoking in our population was primarily due to the emer- gence of dyspnea, coinciding with the age at which the greatest drop in peak expiratory flow values took place, i.e., from 45 to 65 years of age (see Figures 6 and 7).

Only future studies can determine whether current and future campaigns against smok- ing in P&-to Alegre have had any significant effect on smoking patterns. However, it ap- pears that the age of 56 f 11 years (the aver-

Chieb et al. l SMOKING PATTERNS IN P6RTO ALEGRE 41

age age of former smokers in our survey popu- if these campaigns are successful, such studies

lation) could prove a useful indicator for could be expected to show a decline in that age

studies evaluating future campaigns against level.

smoking in our population. The reason is that

ACKNOWLEDGMENTS

The authors are grateful to the staff of the handling, preparing, and programming the

Institute of Social, Political, and Economic data for SPSS computer processing. We are

Studies of the Catholic University of P&-to also grateful to Professor Edgar M. Wagner of

Alegre and to Professor Jolo Becker of the the Federal University’s Statistics Department

Administrative Sciences Department of the for his suggestions and review of the statistical

Federal University of Rio Grande do Sul for analysis.

SUMMARY

During 1980 a survey of smoking habits, obstruc- tive lung diseases, and lung function was conducted in P&to Alegre, Brazil. The aim was to provide basic data needed for assessing the progress of an intensive anti-smoking campaign in that city, and also to learn more about patterns of tobacco use and obstructive respiratory disease in this part of Brazil.

The study area selected was a principally resi- dential section of P&to Alegre extending as a nar- row wedge from the city’s outskirts to its center. Sixty streets within this study area were then se- lected at random, and homes on those streets were visited by two-person teams of medical students. These teams interviewed appropriate subjects over 35 years of age, obtained the answers to queries on a simple questionnaire, determined the subjects’ height, and measured each subject’s peak expira- tory flow rate in order to obtain an indication of pulmonary function. In all, 316 smokers, 102 former smokers, and 122 nonsmokers were includ- ed in the survey.

Of the 418 subjects with a smoking history, 27.6 per cent of the men but only 16.9 per cent of the women had given up the habit-suggesting either that the male population was more responsive to the anti-smoking campaign, more inclined to give up smoking, or more subject to smoking’s harmful ef- fects than women. The data also indicated that the rate at which subjects gave up smoking did not vary so much with socioeconomic status as it did with proximity to the city center. This suggests that liv- ing in a city center that is the hub of an intense anti- smoking campaign could have an important impact upon the propensity to give up smoking.

The only significant correlation found between smoking and lung disease (tuberculosis, pleurisy, or pneumonia) involved women. That is, female sub-

jects who reported a past or present history of such disease appeared less apt to smoke than other women. No differences in the prevalence of asthma among smokers, former smokers, and nonsmokers were detected; but the condition was clearly more prevalent among women than among men in the survey population.

Regarding peak expiratory flows, the study found lower average values for smokers than for nonsmokers. It also found that former smokers’ values did not differ significantly from those of non- smokers, thereby supporting previous findings that the functional damage caused by smoking is at least partially reversible.

Comparison of the peak flow values for smokers and nonsmokers in different age groups showed that the smokers experienced considerably greater average declines over time than did nonsmokers. Overall, this study and others lead to the conclusion that the declines in peak flow values observed after age 50 in smokers-and even among former smok- ers-appear much more pronounced than in other age groups and could signify an increase in respi- ratory distress and premature disability.

Research to date has suggested that a subject must smoke for 20 to 30 years before sufficient obstruction occurs to produce clinically significant dyspnea. In the study reported here, most of the survey subjects began smoking before age 20; most of those who broke the habit had been smoking for 30 years; and the average age of former smokers in the survey population was 56 years. It is therefore tentatively concluded that cessation of smoking in this population was primarily due to the emergence of dyspnea-such cessation coinciding with the age- range, beginning around 45, in which the greatest drop in peak expiratory flow values occurred.

42 PAHO BULLETIN b vol. 18, no. I, 1984

REFERENCES

(1) Wald, N. J. Mortality from lung cancer and coronary heart disease in relation to changes in smoking habits. Lancet 1(7951):136-138, 1976.

(2) World Health Organization. Smoking and Its E’& on Health. WHO Technical Report Series, No. 568. Geneva, 1975, pp. 40-45.

(3) Report to the Medical Research Council by their Committee on the Aetiology of Chronic Bron- chitis. Definition and classification of chronic bron- chitis for clinical and epidemiological purposes. Lancet 1(7389):775-779, 1965.

(4) Gregg, I., and A. J. Nunn. Peak expiratory flow in normal subjects. Br Med J 3:282-284, 1973.

(5) Deeley, T. J., and S. L. Cohen. The Rela- tionship between Cancer of the Bladder and Smok- ing. In: W. B. Diechman and K. F. Lampe (eds.). Bladder Cancer: A Symposium. Aesculopius, Birming- ham, 1967.

(6) Fry, J. Chronic bronchitis in Great Britain: A national survey carried out by the respiratory diseases study group of the College of General Practitioners. Br Med J 2(5258):973-979, 1961.

(7) Russell, M. A. H., C. Wilson, C. Taylor, and C. D. Baker. Smoking habits of men and wom- en. Br Med J 281(6232): 17-20, 1980.

(8) Faro, M. M. Recenciamento toracico pelas unidades moveis de abregugrafia. Rev&a do ServiGo Naciod de Tuberculose (Brazil) 10:37, 69-75, 1966.

(9) Gregg, I. Epidemiology. In: T.J.H. Clark and S. Godfrey (eds.). Asthma. W. B. Saunders,

1977, p. 223. (20) Comstock, G. W., R. W. Stone, J. A. To-

nascia, and D. H. Johnson. Respiratory survey findings as predictors of disability from respiratory diseases. Am Rev Respir Dis 124~367-371, 1981.

(11) Boss& R., P. Costa, M. Cohen, and S. Padolsky. Age, smoking inhalation, and pulmo- nary function. Arch Environ Health 30:495-498, 1975.

(I.?) Burrows, B., R. J. Knudson, M. G. Cline, and M. D. Lebowitz. Quantitative relationships between cigarette smoking and ventilatory func- tion. Am Rev Respir Dis 115:195-205, 1977.

(13) Fletcher, C. M., R. Peto, C. Tinker, and F. Speizer. The Natural History of Chronic Bronchitis and Emphysema. Oxford University Press, 1976.

(14) Flick, A. L., and R. R. Paton. Obstructive

emphysema in cigarette smokers. Arch Intern Med 104:518-526, 1959.

(15) Gibson, J., H. Gallagher, A. Johansen, and I. Webster. Lung function in an Australian population: 2. Spirometric performance and ciga- rette smoking habits. Med J Aust 1:354-358, 1979.

(16) Ashley, F., W. B. Kannel, P. D. Sorlie, and R. Masson. Pulmonary function: Relation to aging, cigarette habit, and mortality; the Framing- ham study. Ann Intern Med 82:739-745, 1975.

(17) Barter, C. E., and A. H. Campbell. Re- lationship of constitutional factors and cigarette smoking to decrease in one-second forced expira- tory volume. Am Rev Respir Dis 113:305-314, 1976.

(18) Burrows, B., and R. H. Earle. Course and prognosis of chronic obstructive lung disease: A prospective study of 200 patients. N Erg1 J Med 280:397-404, 1969.

(19) Howard, P. Evolution of ventilatory capac- ity in chronic bronchitis. Br Med J 3:392-395, 1967.

(20) Corbin, R. P., M. Loveland, R. R. Mar- tin, and P. T. Ma&em. A four-year follow-up study of lung mechanics in smokers. Am Rev Respir Dis 120:293-304, 1979.

(21) Holland, W. W., and D. D. Reid. The ur- ban factor in chronic bronchitis. Lancet 1~445-448, 1965.

(22) Woolf, C. R., and J. T. Suero. The respi- ratory effects of reaular cigarette smoking in wom- #err. Am Rev Respir Dis 103:26-27, 1971.

(23) Buist, A. S., G. J. Sexton, J. M. Nagy, and B. B. Ross. The effect of smoking cessation and modification on lung function. Am Rev Respir Dis 114:115-122, 1976.

(24) Higgins, I. T. T. Tobacco smoking, respi- ratory symptoms, and ventilatory capacity. Br Med

J 5118:325-329, 1959. (25) McCarthy, D. S., D. B. Craig, and R. M.

Cherniack. Effect of modification of the smoking habit on lung function. Am Rev Respir Dis 114: 103- 113, 1976.

(26) Woolf, C. R., and N. Zamel. The respira- tory effects of regular cigarette smoking in women: A five-year prospective study. Chest 78~707-713, 1980.