title: [Health-related behaviors in secondary-school students: sexual relations and tobacco, alcohol and cannabis consumption].
abstract: OBJECTIVE
  The main premature mortality causes among youngsters are related to risk behaviors, usually initiated in adolescence. The study objective is to describe substance use and sexual behaviours among 10th-grade Barcelona students in 1996 (last year of compulsory education), as well as the interrelations between these variables and several sociodemographic variables.
  
  
  METHODS
  Cross sectional study. Random sample including 35 10th grade classrooms (958 students whose mean age is 15.8 years old) stratified by academic or vocational studies, public or private school, school neighbourhood socioeconomical level and school size. Measurement instrument is a previously validated questionnaire. Tobacco, alcohol, and cannabis consumption, sexual intercourse as well as gender, age, weekly available money, parental instruction and type of studies are studied. Bivariate chi 2 analysis and multivariate gender specific log-linear model are performed.
  
  
  RESULTS
  27% of the students smoke daily and 31% drink alcohol weekly. 15% have had sexual intercourse, and among those 79% use always or almost always condoms. Among girls tobacco consumption is related to alcohol (OR = 4.2), to cannabis (OR = 5.9) and sexual intercourse (OR = 3.9), and, less strongly, with age, available money and vocational studies. Alcohol is associated with tobacco and cannabis use (OR = 4.2). Having had sexual intercourse is related to tobacco use, age (OR = 3.4), vocational studies (OR = 2.4) and cannabis experience (OR = 2.8). Among boys tobacco consumption is related to alcohol, (OR = 2.7), to cannabis (OR = 7.6) and sexual intercourse (OR = 4.4), and, less strongly, to available money and type of studies. Alcohol consumption is associated with tobacco and cannabis use (OR = 5.5). Sexual intercourse is related to tobacco use and age (OR = 2.5).
  
  
  CONCLUSIONS
  Risk behaviors among final year secondary school students are strongly and significantly interrelated, both among boys and among girls, and are more frequent among older students, those with more money available and those in vocational curricula.
authors.affiliation: Institut Municipal de Salut Pública, Barcelona.
authors.forename: E
authors.initials: E
authors.lastname: Díez
authors.forename: J
authors.initials: J
authors.lastname: Barniol
authors.forename: M
authors.initials: M
authors.lastname: Nebot
authors.forename: O
authors.initials: O
authors.lastname: Juárez
authors.forename: M
authors.initials: M
authors.lastname: Martín
authors.forename: J R
authors.initials: JR
authors.lastname: Villalbí
mesh_terms: D000293:Adolescent; D000428:Alcohol Drinking / Q000453:epidemiology*; D017280:Condoms / Q000706:statistics & numerical data; D003430:Cross-Sectional Studies; D005260:Female; D015438:Health Behavior; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000453:epidemiology*; D012725:Sexual Behavior / Q000706:statistics & numerical data; D012907:Smoking / Q000453:epidemiology*; D012959:Socioeconomic Factors; D013030:Spain / Q000453:epidemiology; D011795:Surveys and Questionnaires; D014505:Urban Population / Q000706:statistics & numerical data