Prevalence of impaired lower airway function in Thai patients with allergic rhinitis

Abstract

Background: Allergy is a chronic inflammatory disease, which may affect the upper and lower airway in reversible airflow obstruction or asthma. Spirometry is a noninvasive way to assess lower airway function routinely and to detect reversible airflow obstruction. Objectives: To determine the prevalence of abnormal spirometry in Thai patients with allergic rhinitis (AR) who did not have lower airway symptoms. Methods: Spirometry and bronchodilation testing were performed in AR patients. Results: We included 153 patients aged from 20 to 60 years who had AR (diagnosed by clinical data and positive skin prick test) and who fulfilled the study criteria. Twenty-three patients with AR (15%) showed decreased forced expiratory volume in 1 s (FEV1) compared with normal values (FEV1<80% of predicted value). Four patients with AR (3%) showed reversible airflow obstruction. Thirty-seven patients with AR (24%) showed decreased forced expiratory flow during 25-75 s (FEF25-75) compared with the reference value (FEF25-75<80% of predicted value). The sensitization to both indoor and outdoor allergens was statistically and significantly associated with the decreased FEV1(odds ratio (OR) = 7.79, 95% confidence interval (CI) 1.08-55.91, P = 0.03). The duration of AR was more than 10 years significantly affected FEF25-75(adjusted OR = 2.6; 95%CI = 1.01-6.72, P = 0.04). Conclusions: Impaired lower airway function and reversible airflow obstruction in patients with AR are not uncommon. Spirometry should be performed to detect lower airway impairment early in patients with AR, especially those sensitized to indoor and outdoor allergens.