All of the following factors have contributed to a reduction in the prevalence of smoking except

Contextual factors associated with smoking among Brazilian adolescents

1. Sandhi Maria Barreto1,
2. Luana Giatti1,
3. Leticia Casado2,
4. Lenildo de Moura3,
5. Claudio Crespo4,
6. Deborah Malta3,5

1. 1Faculty of Medicine, Universidade Federal de Minas Gerais, Belo Horizonte-MG, Brazil
2. 2National Institute of Cancer, Rio de Janeiro, RJ, Brazil
3. 3Brazilian Ministry of Health, Health Surveillance Secretary, Non Communicable Diseases Coordination, Brasília-DF, Brazil
4. 4National Institute of Geography and Statistics, Rio de Janeiro, RJ, Brazil
5. 5Nursing School, University Federal de Minas Gerais, Belo Horizonte-MG, Brazil

1. Correspondence to Professor Sandhi Maria Barreto, Faculty of Medicine, Universidade Federal de Minas Gerais, Av Alfredo Balena 190, sl 814, Belo Horizonte, CEP 30130100, Minas Gerais, Brazil; barreto{at}medicina.ufmg.br

Abstract

Background Very few studies have examined the role of school, household and family contexts in youth smoking in middle-income countries.

Methods This work describes smoking exposure among 59 992 high school students who took part in the Brazilian Survey of School Health and investigates contextual factors associated with regular smoking, defined as smoking cigarettes at least once in the past 30 days. The explaining variables were grouped into: socio-demographic characteristics, school context, household context and family rapport. Variables independently associated with smoking in each context were identified by multiple logistic regression analysis.

Results 53% of the total sample were girls, 89% were aged 13–15 years. 24% had already experimented with cigarettes, 50% before the age of 12 years. The prevalence of regular smoking was 6.3% [95% CI 5.87 to 6.74], with no sex variation. Smoking was not associated with either the mother's education or the index of household assets. In the multivariable analysis, studying at a private school, the possibility of purchasing cigarettes at school and skipping of classes without parents' consent increased the chances of smoking. In the household context, living with both parents was negatively associated with smoking, while having smoking parents and exposure to other people's smoking was positively related to smoking. In the family context, parental unawareness of what the adolescent was doing increased smoking, but having meals with the mother one or more days per week and parents' negative reactions to adolescent smoking reduced the chances of smoking.

Conclusion The results reinforce the role of school, household and family contexts in youth smoking behaviours and will help improve public health policies aimed at preventing smoking and health promotion in adolescents.

• Smoking
• school health
• adolescence
• health risk behaviour
• adolescents CG
• health behaviour
• smoking RB

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• Smoking
• school health
• adolescence
• health risk behaviour
• adolescents CG
• health behaviour
• smoking RB

Introduction

The exposure to smoking during adolescence has various important implications on the well-being and health of the adolescent, both cross-sectional and longitudinal.1 A cohort study in the USA has shown that half of the students who have experimented with tobacco smoke on a daily basis 1 year later.2 The nicotine addiction can also start in adolescence and is not dependent on the daily use of tobacco. Longitudinal data collected annually from 1246 schools [2002–2006] found that the irregular use of cigarettes [not daily] can trigger nicotine addiction. Symptoms of premature addiction accelerate the frequency of tobacco use, and those who smoke more often tend to show more symptoms of addiction.3 In general, the survey results in this field have shown that out of five adolescents who use cigarettes, one to three are addicted to nicotine.4

Besides causing problems during adolescence, the use of tobacco in adolescence is also associated with use during adulthood.5 Peto et al have shown that the risk of lung cancer among individuals who started smoking before the age of 15 years is twice that of those who started at the age of 20 years or above.6 Life-course analysis shows that adverse circumstances during childhood, including smoking, are associated with a worse self-assessment in terms of health in adulthood.7 Furthermore, a Finnish survey has shown that health-related risk behaviours during adolescence predict lower educational level in adulthood, contributing to an increase in health inequalities.8

The use of tobacco during adolescence is, for the most part, culturally determined. There are various theoretical models to explain how social relations affect the initiation of risk behaviours such as smoking.9 A simpler ecological model of development during young age theorises that there is a complex interaction between individual and contextual factors, including the influence of the community, peers, school, family, society and media in general.10 Several empirical evidences sustain this contextual approach. The legal reinforcement which prohibits selling cigarettes to minors seems to have contributed to the reduction of 47% of the prevalence of daily smokers among youngsters in the USA between 1997 and 2003.11 Students who have schoolmates and/or parents who smoke are more likely to smoke themselves.12 The analyses of trends in school surveys have shown that the exposure to pro-tobacco commercials and smoking at home are positively associated with both the initiation and the maintenance of a smoking habit.13

The present work seeks to describe the exposure to smoking and to identify contextual factors in the school, household and family environments associated with regular smoking among Brazilian high school students who took part in a large, countrywide, school-based health survey.

Material and methods

The National Adolescent School-based Health Survey [PeNSE], a cross-sectional study, was carried out by the Brazilian Ministry of Health among high school students in the 9th grade of public and private high schools in 26 capitals of the Brazilian states and in the Federal District during the months of May and June 2009. Among the 60 973 high school students who participated in the survey, 981 were excluded from the present study because they did not respond to the question about cigarette use in the past 30 days. Of the 59 992 high school students studied, 52.6% were girls, 0.7% were up to 12 years old, 23.7% were 13 years old, 47.1% were 14 years, 18.2% were 15 years old and 10.2% were 16 years or older.

In each city, private and public schools were defined as two strata and the final sample was proportional to the size of the stratum in each municipality. Within each stratum, a cluster sampling was used where the primary sampling unit was the school. Within the school one or two classes from the 9th grade were randomly selected depending on the school size. All pupils in the randomly selected class were invited to participate.

The survey used questionnaires structured for self-application given in the classrooms and filled out by the students on a palmtop computer, the Personal Digital Assistant [PDA]. The questionnaire had modules about several aspects of the life of the high school students: socio-demographic characteristics, diet patterns, body image, physical activities, smoking, consumption of alcohol and other drugs, oral health, sexual behaviour, exposure to violence and accidents, students' perception about family and general appreciation of the questionnaire.

The student's participation was voluntary, with the possibility of no responses to either a few questions or the whole questionnaire. The information obtained and the identity of the school were confidential and unidentifiable. The methodology of the survey has been described by Malta et al.14

Variables

In the present survey, the following items have been used to describe the exposure to smoking: experimentation with cigarettes at some point in life [‘Have you ever smoked a cigarette, even if you just inhaled once or twice?’]; the age of experimentation [‘How old were you when you tried a cigarette for the first time?’]; the regular smoking habit [‘During the past 30 days, how many days have you smoked cigarettes?’]. Considering this last question, students who reported having smoked cigarettes one or more days in the past 30 days were classified as regular smokers.

The magnitude of the associations between individual and contextual factors and regular smoking was determined by the OR and its 95% CIs was obtained by multiple logistic regression. The explaining variables were grouped into four domains according to the thematic affinity of the co-variables, described as follows:

1. Socio-demographic characteristics of the high school adolescent: sex [male and female], age in years, ethnic group/colour [white, black, brown, yellow, indigenous], educational level of the mother [graduate, incomplete undergraduate/complete middle school, incomplete middle school/complete primary education, incomplete primary education, no schooling, not informed] and parental socio-economic status. The last factor was measured by an index of household assets, which varied from 0 to 1 and was grouped in tertiles. To calculate the index, all goods with a prevalence of less than 70% in the sample [home telephone, washing machine, computer with internet connection, car and motorcycle] were taken into consideration, and the weight of each one was defined as 100% minus the relative frequency [%] of the asset in the studied sample. Therefore, assets which were less common received a higher weight.15

2. Contextual characteristics of school: administrative domain [public or private], perception of access to cigarette sale inside the school [yes, no, not aware], reports of having skipped classes without parental permission in the past 30 days [never, 1 or 2 days, 3 or more days] and reports of bullying in school [‘How often has any of your schoolmates made fun of you, joked around, bashed, intimidated or mocked you in such degree that you felt hurt, annoyed, angry, offended, humiliated?’: never, rarely/occasionally, most of the time/always].

3. Household context: family composition [resides with father and mother, only with mother, only with father, doesn't reside with either father or mother], smoking habits of parents or responsible adults [none of them smoke, at least one smokes, both smoke] and number of days in which another person smoked at home in the past 7 days [none, 1–2 days, 3–6 days, every day].

4. Family rapport: has meals with mother or equivalent [every day, at least once a week, rarely, never], parents knew what the child was doing in the past 30 days [always/most of the time, sometimes/rarely, never] and perception of the parents' reaction if they knew that their child was smoking cigarettes [would care a lot, would care little, wouldn't care, don't know].

The research project was registered and approved by the Brazilian Committee of Research Ethics.

Analysis

When cluster sampling is employed, students' responses cannot be assumed to be independent, because school children within the same class are more likely to be similar to each other. A factor was used in the analysis to correct the design effect caused by the complex sampling procedure adopted, given that cluster sampling produces standard errors that tend to be higher than equivalent sample sizes obtained from random sampling. The design factor was defined as the ratio between the SE derived from a complex survey and that obtained by assuming a simple random sample. The analysis was carried out with Stata software [version 11.0] using the ‘svy’ procedure [with weighting factors] appropriate for the analysis of data obtained from complex sampling design. This procedure allows using different weights in the proportional estimation to correct for the different selection probabilities of each school.

The description of the variables experimentation with cigarettes at least once in life and regular smoking are presented by sex and age, and the age of experimentation by sex.

The associations between the independent explanatory variables and regular smoking were measured by Pearson's χ2 test with a significance level of 0.05. The magnitude of the associations was measured by the ORs and its 95% CIs obtained by multiple logistic regression. A multivariate analysis was carried out to identify the variables independently associated with regular smoking in each context analysed, after considering the effect of age and all the co-variables in the same context. The multivariate analysis included all variables related to smoking at a level of p