This study demonstrates that active tobacco smoking in adolescent results in a significantly higher prevalence of respiratory symptoms related to asthma as compared with those who stopped smoking during the last year (ex-smokers) or never smoked tobacco. This finding reinforces the effect of environmental factors, and importantly tobacco smoke, on increasing asthma prevalence. For example, about 27% of asthma symptoms in our adolescents are attributable to active tobacco consumption (population attributable risk). That number is slightly higher than those reported recently by Sturm and colleagues (2004)
who estimated that more than 23% of active asthma cases in North Carolina middle school children were attributable to environmental tobacco smoke and active consumption with a considerable increase of cost in healthcare.
Recently in France, Annesi-Maesano and colleagues (2004)
used ISAAC written questionnaire in adolescents to show more risk for wheezing in the past year among active smokers not exposed to passive smoking and in active smokers exposed to passive smoking than nonsmokers (OR, 95% confidence interval [CI]: 1.7, 1.1–2.4 and 1.9, 1.6–2.2, respectively). In the present study, using ISAAC VQ, the persistent smoker adolescent had significantly more risk for wheezing in the past year than nonsmokers (OR, 95% CI: 1.5, 1.3–1.9, p < 0.001).
Another interesting result in the present study is that adolescents who quit smoking (ex-smokers) have a similar prevalence of asthma-related symptoms than the nonsmokers. Yarnell and colleagues (2003)
used the ISAAC written questionnaire in adolescents in Ireland to demonstrate that only self-report of active smoking but not ex-smoking was a risk factor for severe wheezing episodes. Moreover, Sturm and colleagues (2004)
, using the ISAAC video and written questionnaires in middle school children in North Carolina, found that even low levels of exposure (as low as consuming one cigarette per day) and environmental tobacco smoke at home are independently associated with asthma symptoms. These findings suggest that strong and extensive programs or campaigns against tobacco smoking should be implemented for young children and adolescents as that could decrease the prevalence of asthma and other respiratory problems related to tobacco exposure and potentially prevent tobacco smoking in adulthood.
Although the prevalence of active tobacco smoking among adolescent in our study (16.2%) is higher than reported by other authors using ISAAC questionnaires (13% in North Carolina [Sturm et al 2004
], 9.3% in France [Annesi-Maesano et al 2004
], and 8.5% in Ireland [Yarnell et al 2003
]), it is still in the middle range according to a recent study done in adolescents from different countries where tobacco use in the surveyed age group ranged from 10% to 33% (Warren et al 2000
A limitation of the present study, which is inherent to the ISAAC phase I protocol, is the fact that other risk factors (like family antecedent of asthma or atopy, pets, second-hand smoking, and other environmental factors) were not included in the core questionnaire. However, the main objective of this study is to report the influences of tobacco consumption in adolescents from a low income population.
Similarly to Agudo-Trigueros and colleagues (2000)
, we found significantly more females actively smoking tobacco than males, but this finding has not been consistently reported by another author (Annesi-Maesano et al 2004
). Our finding that more female adolescents are actively smoking tobacco is striking because of the future implications of tobacco smoking in women at fertile age, considering the well known relationship existing between tobacco consumption during pregnancy and asthma-related symptoms in childhood, independently of a family history of asthma, socioeconomic factors, and birth weight (Stein et al 1999
). In addition, we may be witnessing the success of tobacco industry advertising in making cigarettes fashionable, particularly for children living in unprivileged conditions.
In conclusion, our findings strongly suggest that active tobacco consumption increases the prevalence of asthma-related symptoms. More than 27% of asthma symptoms in our adolescents may be attributable to active tobacco consumption (population attributable risk). Therefore, questions on active tobacco smoking should be included in every epidemiological research on asthma related symptoms in children, especially in developing countries where the consumption of tobacco at those ages, as well as environmental tobacco smoke exposure, is markedly increasing. This study strongly suggests that massive and more effective campaigns against tobacco smoking should be implemented in developing countries, where active tobacco smoking is dramatically increasing in adolescents, particularly females.