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[Predictors of the onset of tobacco consumption among secondary school students of Barcelona and Lleida].

BACKGROUND
Knowing the factors predisposing the smoking onset of smoking at school age may help to improve the preventive strategies and make the starting age later. This study is set out to describe the natural history of smoking throughout the teen-age years and the main factors which may predict teenagers developing the smoking habit.


METHODS
This is a longitudinal study of a survey type, using the school room as the sampling unit at six schools in Barcelona and Lleida. A total of 1,460 students within the 12-19 age range took part. Two surveys were conducted, an initial survey in the spring of 1992 and a follow-up survey one year later. A total of 1,236 questionnaires (84.3%) were paired by means of a personal code used for the longitudinal study.


RESULTS
A total of 25% of the students were regular smokers at the start of the study, 17.1% smoking occasionally or having experimented with smoking, there being no differences between sexes for both of these categories. Among those who were non-smokers at the starting survey, 12.7% stated that they smoked occasionally and 6.2% regularly one year later. The females started smoking at an earlier age, the differences as compared to males being statistically significant at 14 years of age. The predictors of the smoking onset include favorable attitudes toward cigarettes (OR = 3.1; CI5% (1.6-5.6), drinking alcoholic beverages (OR = 2.2; CI95% (1.4-3.3), being younger than age 15 (OR = 2.0; CI95% (1.2-3.4), having friends who smoke (OR = 1.9, CI95% (1.2-3.0) and the stated intention of smoking in the future (OR = 1.6; CI95% (1.0-2.5).


CONCLUSIONS
The students showing a higher degree of tolerance toward cigarette smoking, entailing favorable attitudes or friends who smoke or who intend to smoke in the future at the start of the study are at a much higher risk of Smoking onset than their classmates who are not of these characteristics. The cigarette smoking prevention programs must focus special attention on the teenagers most highly vulnerable to these factors.