INTRODUCTION

It is estimated that tobacco use causes nearly six million deaths per year worldwide, and about 600,000 people die every year from exposure to secondhand smoke worldwide. The prevalence of tobacco use in the world is estimated at about 22%, being higher in men (37%) than in women (7%). Smoking increases the risk of cardiovascular diseases, cancer, respiratory diseases, diabetes mellitus and premature deaths¹.

A survey conducted with Brazilian adolescents in 26 capitals and the Federal District found prevalence rates of 22.7% for cigarette experimentation, 6.1% smoker regular and 7.1% tried other tobacco products, with half of these smokers regular². Another study shows a prevalence of 29.3% for tobacco experimentation, and states that 14.5% started smoking before the age of twelve³. Other studies^4,5 also showed early cigarette experimentation by children and adolescents, beginning around 11 years of age.

In view of the aforementioned, the tobacco industry has targeted its marketing to teens and young adults, as they are likely to experiment with tobacco when they have smoking parents and friends. Therefore, controlling the exposure of smoking characters in the cinematic media should be considered to prevent tobacco experimentation⁵. In Brazil, a high prevalence of tobacco experimentation has been detected in adolescents enrolled in public high schools^6,7,8. However, tobacco experimentation has also been found among students enrolled in private schools^{(9, 10)}. In the capitals of Brazilian states the prevalence of cigarette experimentation is higher among male students, except for the states of Paraná and Rio Grande do Sul¹¹.

Data from studies conducted in Brazil and worldwide revealed that adolescents are the group with the highest risk for smoking initiation¹¹. Thus, in the 1990s, Brazil has banned tobacco sales to minors under 18 years to reduce this prevalence. However, due to lack of enforcement, such legislation failed to prevent adolescents from buying cigarettes⁵, So, more effective control of the retail sale of cigarettes and other tobacco products is required.¹².

Adolescents are influenced by environments such as family, group of friends, community, advertising and school setting. These environments play a key role in the initiation of adolescents in tobacco use. Moreover, since adolescence is a stage of transition to adulthood, a period marked by doubts and needs for peer acceptance, tobacco experimentation is an education issue, rather than merely a public health one¹³.

Given that tobacco experimentation is a key factor for youngsters to initiate smoking¹, the present study aimed to identify the prevalence and factors associated with tobacco experimentation in adolescents living in the city.

METHOD

Cross-sectional, descriptive and analytical epidemiological study with adolescents aged 14-19 years enrolled in public high schools in the urban area of the city of Jequié, Bahia.

Eligibility criteria were participants aged of 14-19 years, enrolled in public high schools, in the morning, afternoon and evening shifts; present in the classroom at the time of data collection and submission of the free informed consent form signed by their parents/guardians in the case of participants under 18.

The sample was calculated using a prevalence of 10% for tobacco consumption, 95% confidence level and 2% accuracy, resulting in an initial sample of 714 students. To compensate for possible losses and refusals, 30% was added to the final sample, which was composed of 928 students. Simple random sampling without replacement was used. In order to identify the sample interval (n = 4), the school population was divided by the value obtained in the sample calculation. Then, the first sampling element was drawn and the sampling interval was added successively.

Data was collected through a self-administered instrument validated and used in the Vigescola study¹¹, and a questionnaire was proposed by the Brazilian Marketing Research Association (ABEP) to evaluate the economic classification¹⁴.The instrument contained socio-demographic variables (gender, age, economic status, ethnicity, paternal and maternal education, religious belief, paid work, persons living with the respondent and breadwinner) related to smoking (cigarette experimentation, smoking parents and friends) and alcohol drinking.

As a dependent variable, in this study tobacco experimenters were considered high school students who at some point in their life tried or experimented cigarettes, even if only one or two puffs. The variables age group, parental schooling, and economic status were classified, respectively, in 14 to 16 and 17 to 19 years old, low educational level (<8 years of schooling) and high educational level (> 8 years), higher economic status (A2, B1 and B2) and low economic status (C1, C2, D and E).

Data was collected in the period of July-September 2012 by a standardized team, in the classrooms or in the school auditorium. No teachers or school coordinators were present at the collection site during data collection. Any misunderstandings or doubts during the completion of the questionnaire were clarified by the research staff. To ensure data confidentiality, each respondent placed the completed questionnaire, without identification, inside a box.

Descriptive analysis of the variables was performed, calculating the absolute and relative frequencies, as well as the mean and standard deviation for the continuous variables. Association between tobacco experimentation (dependent variable) and sociodemographic, economic data, alcoholic beverages and the influence of family environment and friends (independent variables) was tested using Poisson regression. Robust models were calculated to estimate the prevalence ratios (PR), with their respective 95% confidence intervals (95% CI). In all analyzes, the statistical significance was 20% (p <0.20). The data were tabulated and analyzed using SPSS for Windows, version 15.0

The study was approved by the Research Ethics Committee of Universidade Estadual do Sudoeste da Bahia (CEP/UESB), under protocol no. 212/2011.

RESULTS

The sample consisted of 765 school adolescents with an average age of 16.5 years (SD ± 1.33). The causes of losses and refusals were partially completed questionnaires, lack of parental authorization, and the fact that some students did not feel comforTable participating in the study

Table 1 contains data related to the characterization of the sample of high school students

Table 1. Socioeconomic-demographic characteristics, tobacco experimentation, smoking friends and family members, and alcohol drinking among high school students (N=765). Jequié-BA, Brazil, 2012. 

Source: Research data

As it can be seen inTable 1, most individuals were female subjects (59.9%), non-white (80.4%), 14-16 year old (51.8%), with religious beliefs (85, 1%), who had no paid job (71.1%), who live with father and mother (54.4%), of low income families (74.0%), whose parents are the breadwinners (82.5% ), whose parents have low educational level (54.7%), whose mothers have a high level of education (52.7%), whose parents (79.1%) and friends (63.3%) don’t smoke and don’t drink alcohol regularly (62.1%).

The prevalence of tobacco experimentation was 22.4%, and of these, 10.6% were aged 12 -15 years old.

Table 2 contains data from the bivariate analysis of tobacco experimentation and associated factors among adolescent high school students.

Table 2. Tobacco experimentation and associated factors among high school students 

Source: Research data

Based on Table 2, there is a statistically significant difference between tobacco experi tation and the variables: gender (p = 0.002, PR = 0.65, 95% CI = 0.50-0.85), paid work ( P = 0.001, PR = 1.57, 95% CI = 1.19-2.05), age group (p = 0.005, PR = 0.67, 95% CI = 0.51-0.88), smoking parents (p = 0.001, PR = 1.72, 95% CI = 1.29-2.30), smoking friends (p = 0.001, PR = 2.59, 95% CI = 1.97-3.39), and alcohol drinking (p = 0.001, PR = 3.08, 95% CI = 2.28-4.17), Students who have smoking friends (crude PR = 2.59) and who drink alcohol regularly (gross PR = 3.08) are at the highest risk of experiencing tobacco

The variables: gender, age group, paid work, religious belief, economic class, parents who use tobacco, friends who smoke and use alcohol regularly were inserted in the multiple analysis. As shown in Table 3, the predictive model generated allowed the identification of the set of variables that best predict the predisposition of a student to experience tobacco, as follows: parental smoking (p = 0.004, PR = 1.57, 95% CI = 1.15-2.12), smoking friends (p <0.001, PR = 2.15, 95% CI = 1.56-2, 95% CI = 1.46-2.88), 17-19 age group (p = 0.04, PR = 1.36, 95% CI = 1.01-1.84).

Table 3. Poisson regression model used to identify variables associated with tobacco experimentation by adolescents Jequié, Bahia, Brazil, 2012. 

Source: Research data

The variables gender (p gross analysis =0.002, p = adjusted analysis = 0.05), and paid work (p gross analysis = 0.001; p adjusted analysis = 0.14) lost statistical significance in multiple analysis (Table 3) compared to gross analyzes (Table 2).

DISCUSSION

The present study allowed the identification of the risk factors associated with tobacco experimentation in adolescents living in a city in the inland of Bahia.

The prevalence of tobacco experimentation in the studied population was 22.4%, corroborating with data from a study with 61,037 adolescents living in Brazilian capitals (22.7%)², and a study conducted in Uruguaiana, Rio Grande do Sul (29 .3%)³.

Another important aspect to be considered regarding tobacco experimentation is the age of initiation. In the present study, the mean age was 16.55 years, higher than that the one found in other studies on the subject, and 10.6% of the respondents aged 12 -15 years reported tobacco experimentation. A study with children with a mean age of 11.5 years found that 13.3% of them had previously experimented cigarettes⁵. Another study showed a similar mean for the age of first cigarette trial 11.1 years (5-14 years). In Uruguaiana, 14.5% of adolescents started smoking before 12 years of age³, and in Santarém-PA, the mean age of students during cigarette experimentation was 12.37 years (SD ± 1.84 years)⁶.

There is a growing concern with the identification of health risk behaviors in adolescents, such as smoking, since this time of life is characterized by exploration of unknown and “forbidden” territories. Habits acquired in adolescence can persist and lead to dependence, jeopardizing the health of the individuals throughout life. Tobacco experimentation may be an important indicator of predictive risk for illicit drug use⁷ and for the consolidation of smoking^{(13, 15)}.

The earlier the initiation and dependence on tobacco use, the greater the risks for sickening and premature death in mature age, and the difference of years in the beginning of cigarette smoking may increase almost twice the risk of health problems¹⁶. Therefore, it is important to implement and expand effective public policies to prevent tobacco consumption, especially for adolescents, aiming to reduce experimentation and transition from tobacco to continuous use of cigarettes, and to the development of non-chronic diseases. communicable diseases^1,6,9.

In the present study, the variables that best predict adolescents who may experience tobacco are age group, smoking parents, smoking friends, and adolescents who drink alcohol.

Regarding age, it was found that the individuals aged 17-19 years were more likely to experiment tobacco. A study with adolescents living in Brazilian capitals where the probability of experimentation and regular use of smoking increases with age corroborates our findings². Similar results were also found in brown-colored older boys from high-income families⁽¹⁰, with students from Cuiabá-MT⁽⁸and with students of Varzea Grande-MT regarding narghile use, which was associated with the final period of adolescence⁹.

The present study found that the risk of experiencing tobacco is higher in adolescents who have smoking parents and friends. The presence of a smoker at home and having smoking friends are significant risk factors for the onset of smoking. A study with adolescents aged 12-19 years in Uruguaiana, Rio Grande do Sul, reported an association between the habit of smoking and having a smoking friend (OR: 5.67, 95% CI 2,06-7,09)³. Another study based on data from the National Survey of School Health - 2012 found that adolescents who have smoking friends and parents and spend more time with smoking persons are more likely to experience tobacco, ( OR = 4.27, IC 95% 3.82-4.77)².

For students of public schools in the State of Pará, tobacco consumption by parents and friends was also associated with experimentation⁶.These results show the importance of social relationships for the formation and decision making of adolescents, given that in this stage, the individuals search for a sense of self and personal identity.

A study with adolescent students from Jequié, Bahia, found that students who regularly drink alcohol were at a higher risk of tobacco experimentation (OR = 2.05). Alcohol has become a factor associated with cigarette experimentation and the habit of smoking, either in children (p <0.001)⁵ or in adolescents who have experimented smoking⁶. Thus, more public investments are needed to reduce tobacco experimentation and alcohol drinking, since both are extremely harmful for individuals of all ages.

The present study had some limitations, as follows: 1) its cross-sectional design that makes it difficult to derive causal relationships; 2) the fact that data collection covers only adolescents enrolled in public high schools in the urban area of the municipality; and 3) information bias, since, despite the guarantee of anonymity, some students may have omitted the experimentation of tobacco or alcohol use due to self-censorship, shame or memory bias.

On the other hand, the possibility of information bias in the study is reduced because the sample is composed of high school students from public schools located in the study site. In addition; epidemiological investigations with a cross-sectional design are relevant for the development of public policies. We suggest new prospective studies to assess the causal relationship between the factors that influence the risk for tobacco experimentation in adolescents and, consequently, dependence and health damage in adulthood.

CONCLUSION

There was a high prevalence of tobacco experimentation among high school students aged 14-19 years of public schools in the urban area of the city of Jequié, Bahia.

The set of variables that best identifies the risk factors that may lead adolescent students to experience tobacco in the study population were smoking parents, smoking friends, regular alcohol drinking, and age group 17-19 years.

The results obtained indicate the need to implement more effective local public policies aimed to prevent tobacco experimentation and ensure proper treatment for smokers, since adolescents with smoking parents and friends are more likely to experiment cigarettes.