title: The prevalence of and variables associated with smoking in children and adolescents.
abstract: OBJECTIVE
  To identify the prevalence of smoking and the presence of variables associated with the habit in children and adolescents of both sexes, aged 7 to 17 years, resident in the city of Maceió.
  
  
  METHODS
  A cross-sectional epidemiological study of the student population of the both private and public education systems at elementary and high school level. Sample size was calculated based on the minimum predicted prevalence of a large number of variables, including smoking itself. Cluster sampling was employed. A questionnaire on smoking habits was completed during individual interviews with each student. Children who admitted having smoked on 1 or more day during the previous 30 were defined as current smokers. The variables analyzed were related to: the students (age, sex, previous experimentation with cigarettes and paid employment), their educational status (public/private school, daytime/evening lessons, grade and repeated years) and their families (economic status, smoking parents and separated parents).
  
  
  RESULTS
  A total of 1,253 students were analyzed (547 were male, mean age was 12.4+/-2.9 years). Observed smoking prevalence was 2.4%. Multivariate statistical analysis demonstrated significant associations between smoking and: increased age (odds ratio: 1.31); previous experimentation with cigarettes (odds ratio: 33.96); studying during the evening (odds ratio: 5.43). It was observed that 286 students (22.8%) admitted having experimented with cigarettes (9% from 7 to 9 years; 21% from 10 to 14 years; 36% from 15 to 17 years).
  
  
  CONCLUSIONS
  The prevalence of smoking among children and adolescents in the Maceió educational system is 2.4%, being most common among students aged 15 to 17 years, studying in the evening. Students who had experimented with cigarettes exhibited a 34 times greater chance of becoming smokers.
authors.affiliation: Faculdade de Medicina, Universidade Federal de Alagoas (UFAL), Maceió, AL. malayde1@uol.com.br
authors.forename: Maria Alayde M da
authors.initials: MA
authors.lastname: Silva
authors.forename: Ivan R
authors.initials: IR
authors.lastname: Rivera
authors.forename: Antonio Carlos C
authors.initials: AC
authors.lastname: Carvalho
authors.forename: Armando de H
authors.initials: Ade H
authors.lastname: Guerra
authors.forename: Tereza Cristina de A
authors.initials: TC
authors.lastname: Moreira
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002652:Child Behavior; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D015995:Prevalence; D012907:Smoking / Q000453:epidemiology*; D012923:Social Class; D013334:Students / Q000706:statistics & numerical data*; D011795:Surveys and Questionnaires