Impact of obstructive sleep apnea on severe asthma exacerbations.

BACKGROUND: Patients with asthma have a higher incidence of obstructive sleep apnea (OSA). However, the association between OSA and the exacerbation of severe asthma remains unclear. In this study, we aimed to investigate the prevalence of OSA in a cross-sectional study of asthma patients and to prospectively examine the significance of the effect of OSA on severe asthma exacerbations.

METHODS: One hundred and forty-six patients with asthma and 157 matched-controlled individuals were enrolled in this study. The patients with asthma were prospectively studied for one year, and exacerbation episodes were identified based on the patients' medical histories. Lung function and the percentages of eosinophils in induced sputum samples were determined, and the frequencies of severe asthma exacerbations during the previous year were evaluated in the group of patients with asthma.

RESULTS: The rates of OSA were 19.2% (28/146) among the patients with asthma and 9.6% (15/157) among the control individuals (p = 0.016). The frequency of severe asthma exacerbations was significantly higher among the asthma patients with OSA compared with those who did not have OSA (p < 0.001). The apnea-hypopnea index (AHI) correlated significantly with the number of severe asthma exacerbations (r = 0.507, 95% confidence interval [CI] 0.357-0.637, p < 0.001). Logistic regression analyses determined that the AHI was significantly associated with the occurrence of severe asthma exacerbations (odds ratio 1.322, 95% CI 1.148-1.523, p < 0.001).

CONCLUSIONS: Patients with asthma had a high prevalence of OSA, which was an important factor associated with severe asthma exacerbations.