Mild respiratory symptoms in asthmatic patients might not be due to bronchoconstriction

BACKGROUND: Although respiratory symptoms in asthmatic patients are likely to be caused by bronchoconstriction, this should be confirmed by spirometry. In this study, our aim was to determine the percentage of asthmatic patients who present with mild respiratory symptoms but fail to show any evidence of bronchoconstriction in spirometry. MATERIALS AND METHODS: A total of 428 known asthmatic patients (57.5% females) participated in the study. Inclusion criteria were age ≥16 years, known asthmatics for at least 1 year, presenting with mild respiratory symptoms including cough, wheezes, shortness of breath, and chest tightness. Patients presenting with moderate or severe asthma exacerbations were excluded from the study. Spirometry measurements were performed according to the guidelines of the American Thoracic Society. SPSS was used for data analysis. The percentage of patients who did not show any evidence of airway obstruction was calculated. For spirometry variables, mean and standard deviation were calculated. For the categorical variables, Chi-square test was performed to determine statistical significance at alpha=0.05. RESULTS: Typical obstructive pattern was found in 38 (or 9%) of all participants. Evidence of obstruction within small or middle airways was found in all those who showed an obstructive pattern and more than 90% of those who showed restrictive or mixed patterns. About 11% of the participants showed a normal spirometric pattern with no evidence of small airway obstruction. Statistical analysis showed an insignificant relation between patterns of spirometry and gender or body mass index of the participants. CONCLUSION: About 11% of asthmatic patients with mild respiratory symptoms who attended the respiratory clinic have no evidence of bronchoconstriction. Spirometry is an essential step for evaluation of every asthmatic patient who presents with respiratory symptoms.