Prevalence of Obstructive Sleep Apnea-Hypopnea in Severe Asthma

Background: Obstructive sleep apnea syndrome (OSA) and asthma are two common respiratory diseases. An overlap between the two diseases has been widely reported. It is established that OSA may affect control of asthma. This study aims to highlight OSA prevalence in patient with difficult to control asthma and to point out the feature of this overlap syndrome. Methods: We conducted a prospective study including sixty patients with difficult control asthma who had symptoms suggestive of OSA (Epworth scale>10). Based on the findings of the respiratory polygraphy, a comparative analysis of clinical, biologic, lung function testing and therapeutic features was performed. Results: OSA was confirmed in 63.3% of cases, and was severe, moderate and mild in 26%, 61% and 13% of them respectively. Comparison between the OSA and non-OSA arms showed no significant differences in the asthmatic disease features: date of onset, atopy, history of near fatal asthma and medication use. However, OSA patients were older than non OSA patients (54 vs. 45 years old; p=0.05). Furthermore there was a difference in the proportion of males between both arms (50% in OSA vs 23% in non OSA; p=0.05). Gastro-oesophageal reflux disease (GERD) was more common in the OSA group (57.9% vs. 21.7%; p=0.034). There was no significant difference between the two arms regarding obesity, allergic rhinitis and smoking. Conclusion: This study shows that OSA is more prevalent in difficult to control asthma patients. The presence of overlap syndrome was correlated with age, male gender and GERD.