[Health-related behaviors in secondary-school students: sexual relations and tobacco, alcohol and cannabis consumption].

BACKGROUND AND OBJECTIVES: 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). DISCUSSION: 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.