Children passive smoking jeopardises the efficacy of standard anti-allergic pharmacological therapy, while sublingual immunotherapy withstands.

BACKGROUND The association between genetic predisposition and environmental risk factors such as passive smoke in determining respiratory allergies is still uncertain; even less is known about the role played by passive smoking in influencing the success of therapy for rhinitis and allergic asthma. OBJECTIVE The purpose of this prospective, randomised study was to determine whether passive smoking influences the outcome of therapies in paediatric patients with allergic respiratory diseases. METHODS The study included 68 children (mean age 11.51 years; range: 5-17) suffering from perennial rhinitis and intermittent asthma monosensitised to Dermatophagoides. Thirty-four subjects were exposed to daily passive smoking in their families, 34 were not. The two groups have been then randomised to receive continuous treatment with cetirizine or SLIT for three years. RESULTS There were 3/34 (8.8%) dropouts in the SLIT arm and 4/34 (11.7%) in the cetirizine arm. After three years, the patients exposed to passive smoking showed higher nasal eosinophilia, a worse clinical-symptomatic and pharmacological score with a worsened bronchial reactivity and functional indices of persistent asthma, regardless of how they had been treated. Nevertheless, SLIT prevented the worsening of all the clinical parameters more than the antihistamine alone either among the children exposed to smoking or not. CONCLUSIONS Exposure to passive smoking in children suffering from respiratory allergies due to Dermatophagoides decreased the clinical response to both drug therapy and SLIT. Nonetheless, while the children submitted to drug therapy worsened or did not show any significant improvement, the ones treated with SLIT improved.