High prevalence of rhinitis symptoms without allergic sensitization in Estonia and Finland

Objectives: Allergic rhinitis and atopy are more common in urban than rural environments. Non-allergic rhinitis has not been studied to a great extent. We aimed to assess the relationship of rhinitis symptoms with different profiles of allergic sensitization, comparing this in rural and urban environments. Methods: The study population consisted of population-based cohorts of adults aged 26 - 60 from Helsinki, Finland, and rural Saaremaa and urban Tallinn, Estonia. We compared the results of a structured interview and skin prick tests and assessed the risk factors for rhinitis. Results: The prevalence of rhinitis symptoms with atopy was 32.7% in Helsinki, 20.8% in Tallinn, and 12.5% in Saaremaa (p <0.001). Rhinitis symptoms without atopy were found in 26.4%, 29.8%, and 29.3% (p = n.s.), respectively. In Helsinki, 87.3% of participants with atopy identified symptoms as allergic, compared to 57.0% in Tallinn and 47.5% in Saaremaa. Childhood in the countryside (OR 0.63), family history of allergic rhinitis (OR 1.89), and polysensitization (OR 15.99) were significantly associated with rhinitis symptoms with atopy in a multivariate logistic regression model. The most common sensitizers were pollens and animals in Helsinki and mites in Estonia. Exposure to environmental tobacco smoke (OR 1.50) and family history of allergic rhinitis (OR 1.70) were associated with rhinitis symptoms without atopy. Conclusion: Rhinitis symptoms without allergic sensitization were common in both Finland and Estonia and were associated with environmental tobacco smoke. Family history of allergic rhinitis predisposed to rhinitis symptoms irrespective of atopy status.