The heterogeneity hidden in allergic rhinitis and its impact on coexisting asthma in adults: a population-based survey

Background: It has been suggested that there is some overlap between allergic rhinitis (AR), sinusitis and polyposis but it has not been fully documented. This study aimed to evaluate the prevalence of these coexisting diseases and their impact on bronchial asthma in the general population in Italy. Methods: In the frame of the multicentre Gene Environment Interactions in Respiratory Diseases (GEIRD) study, a postal screening questionnaire including questions about self reported symptoms of asthma, AR, ARwith Sinusitis without Nasal Polyps (AR+SsNP) and ARwith Sinusitis with Nasal Polyps (AR+SwNP) was administered. A random sample of subjects (n=5162) aged 20-44 years was selected in 4 Italian centres (Pavia, Sassari, Torino, Verona). In allergic rhinitis subjects, the association among AR only, AR+SsNP, AR+SwNP, and bronchial asthma was estimated by the Relative Risk Ratio (RRR) using multinomial regression models adjusted for sex, age, smoking habits and design confounders. Results: The prevalence of AR in the sample was 25.4% (95%CI: 24.2-26.6). The self-reported diagnosis of AR+SsNP and AR+SwNPwas reported by 5.7% (95%CI: 5.0-6.3) and by 1.2% (95%CI: 0.9-1.5) of the subjects respectively. Current asthma was reported by 17.5% of the AR subjects. In the adjusted multivariate analysis, the risk of having current asthma (RRR=2.31; 95%CI:1.29-4.15), of having at least 1 asthma attack/year (RRR=2.30; 95%CI:1.19-4.46) and of having an emergency department admission for respiratory diseases (RRR=5.61; 95%CI:1.81-23.92) was higher for subjects with AR+SwNP , than subjects with AR only. Conclusions: The diagnosis of allergic rhinitis in the epidemiological setting includes heterogeneous upper airway diseases that affect the clinical features of AR and its interactions with asthma.