Epidemiology of rhinitis in Portugal: evaluation of the intermittent and the persistent types

Background: The prevalence of rhinitis is rapidly increasing in recent years and has become a major public health problem in developed countries. A new classification of allergic rhinitis has been proposed by the allergic rhinitis and its impact on asthma group. In this study we aimed to evaluate the prevalence of rhinitis, including different rhinitis subtypes and to describe the severity, rate of diagnosis and use of medication in this pathology. Methods: A cross-sectional, population-based study including 6859 questionnaire responses was performed. Results: The estimated prevalence of rhinitis was 26.1% (48% for intermittent vs 52% for persistent rhinitis). Only about one-third of the rhinitis cases (31.9%) had done skin prick tests (35.3% for persistent rhinitis vs 21.5% for intermittent rhinitis: P < 0.001) or had medication prescribed in the last year (34%), (35.6% for persistent rhinitis vs 20.1% for intermittent rhinitis : P < 0.001). The prevalence of rhinitis was higher in women (28.2 vs 22.2%; P < 0.001). Intermittent/persistent rhinitis showed the following percentages : <= 25 years (65.6 vs 34.5, P = 0.001); 25-65 years (50.2 vs 49.5) >= 65 years (52.1vs 47.9). The estimated prevalence of rhino conjunctivitis was 18.4%. In a severity scale from 0 to 10, the mean value was 6.1 points (6.4 for persistent rhinitis vs 4.8 for intermittent rhinitis: P < 0.001). Conclusion: A significant prevalence of rhinitis and rhino conjunctivitis was identified in all age groups. The severity, the frequency and duration of the symptoms which classify the persistent type should be considered to establish a more effective treatment and improve the quality of life of the patients with rhinitis.