The Heterogeneity Hidden in Allergic Rhinitis and Its Impact on Co-Existing 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 this has not been fully documented. The present study aimed to evaluate the prevalence of these co-existing diseases and their impact on bronchial asthma in the general population of Italy. METHODS: Within 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, AR with sinusitis without nasal polyps (AR + SsNP) and AR with sinusitis with nasal polyps (AR + SwNP) was administered. Random samples of subjects aged between 20 and 44 years (n = 5,162) answered the postal questionnaire in 4 Italian centres (Pavia, Sassari, Turin, Verona). In AR 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. RESULTS: The prevalence of AR in the sample was 25.4% (95% CI 24.2-26.6). A self-reported diagnosis of AR + SsNP and AR + SwNP was 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 per year (RRR = 2.30, 95% CI 1.19-4.46) and of having had 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 AR in the epidemiological setting includes heterogeneous upper airway diseases that affect the clinical features of AR and its interactions with asthma.