Nonallergic rhinitis and its association with smoking and lower airway disease: A general population study

Background: The cause of nonallergic rhinitis (NAR) and its relation to lower airway disease remains unclear. The purpose of this study was to perform a descriptive analysis of the occurrence of rhinitis in a Danish general population with focus on NAR and its association with smoking and lower airway disease. Methods: A population-based, cross-sectional study conducted in Copenhagen, Denmark was performed. A random sample from the general population (n = 7931; age, 18-69 years) was invited to a general health examination including measurements of serum-specific immunoglobulin E (IgE) to common aeroallergens; 3471 (44%) persons were accepted. For further analysis, we divided the population into the following groups: (I) negative specific IgE and no rhinitis (controls); (II) negative specific IgE and rhinitis (NAR); (III) positive specific IgE and rhinitis (allergic rhinitis [ARA]; and (IV) positive specific IgE but no rhinitis (sensitized). Results: We found that NAR was associated with asthma (odds ratio [OR] = 2.51 [0.87-3.37]; chronic bronchitis (OR = 2.27 [11.35-2.79]; current smoking (>15 g/day; OR = 1.57 [1.18-2.08]; lower forced expiratory volume in 1 second/forced vital capacity (FEV(1)/FVC) ratios and reduced FEV(1) values. The association with chronic bronchitis was stronger in NAR than in AR, whereas the opposite was true for asthma. FEV(1)/FVC of <70% was not significantly associated to any group. Conclusion: This epidemiological study indicates that both asthma and chronic bronchitis are important comorbidities in NAR confirming the "united airway" hypothesis, and that smoking might be a significant modulator of disease. Although NAR was significantly associated with poor lung function, no significant association with chronic obstructive pulmonary disease was shown. (Am J Rhinol Allergy 25, 25-29, 2011; doi: 10.2500/ajra.2011.25.3556)