Active and passive tobacco and nicotine product exposure and asthma control in adolescents: a retrospective study from a pediatric allergy clinic

Background Active tobacco and nicotine product use may adversely affect asthma in adolescents, but evidence from pediatric allergy clinics simultaneously evaluating active use, passive smoke exposure, asthma control, respiratory symptoms, and lung function remains limited. We examined associations between tobacco/nicotine exposure and asthma-related outcomes in adolescents receiving specialist allergy care. Methods In this retrospective observational study, 238 adolescents aged 14–18 years with physician-diagnosed asthma were screened at a tertiary pediatric allergy clinic in İzmir, Türkiye, between January 2023 and July 2026; 208 met the eligibility criteria and were analyzed. Participants were classified at the most recent follow-up assessment as active tobacco/nicotine users (cigarettes, electronic cigarettes/e-puff, waterpipe, or multiple products; n = 50), passive-only exposed ( n = 77), or unexposed ( n = 81). Baseline spirometry was obtained at the initial visit, whereas Asthma Control Test (ACT) score, respiratory symptoms, asthma attacks during the preceding year, and treatment adherence were assessed at the most recent follow-up. Multivariable logistic regression evaluated uncontrolled asthma (ACT <20) and ≥1 asthma attack. Sensitivity analyses excluded active users with concurrent passive exposure and modeled ACT as a continuous outcome using multivariable linear regression with heteroskedasticity-robust standard errors. Results Active users had lower ACT scores than passive-only and unexposed adolescents (median, 19 vs. 22 and 21; p < 0.001), and uncontrolled asthma occurred in 62.0%, 29.9%, and 34.6%, respectively ( p < 0.001). After adjustment, active use was associated with uncontrolled asthma (adjusted odds ratio [aOR], 3.15; 95% confidence interval [CI], 1.45–6.81; p = 0.004), whereas passive-only exposure was not (aOR, 0.82; 95% CI, 0.42–1.62; p = 0.574). Active use was also associated with ≥1 asthma attack in the primary model (aOR, 2.20; 95% CI, 1.02–4.76; p = 0.044), but this estimate was not robust after excluding active users with concurrent passive exposure. In the continuous-ACT sensitivity analysis, active use was associated with a 2.43-point lower ACT score (adjusted β , −2.43; 95% CI, −3.87 to −0.99; p = 0.001). Conclusions Among adolescents with asthma receiving specialist allergy care, current active tobacco/nicotine product use was associated with poorer asthma control. The association with recent asthma attacks was less robust, and passive-only exposure was not independently associated with the studied outcomes. Because exposure was self-reported and the study was retrospective and single-center, the findings should be interpreted as associations rather than causal effects.