Background: Obstructive sleep apnoea syndrome (OSAS) and severe asthma are frequently associated. This article focuses on the relationship between severe asthma phenotypes and OSAS.

Methods: FASE-CPHG was an observational, cross-sectional, prospective, multicentric study conducted in 104 non-academic hospitals from May-16 to July-17. 1465 patients with severe asthma were analysed and 1424 patients phenotyped. Clusters were compared for OSAS presence; independent factors associated with OSAS were identified by logistic regression.

Results: 11% of patients with severe asthma reported OSAS. OSAS incidence differed according to asthma phenotypes. 98% of OSAS patients belonged to the “obese asthma” cluster, and none to the “early onset allergic asthma” cluster. Independent factors associated with OSAS were obesity (OR=5.782 [3.927-8.512]), male gender (OR=3.047 [2.059-4.510]), high blood pressure (OR=2.875 [1.978-4.181]), depression (OR=2.552 [1.607-4.050]), late-onset asthma (OR=1.789 [1.167-2.743]) and atopy (OR=0.622 [0.408-0.948]). Moreover, OSAS patients were more frequently treated with long-term oral corticosteroids (30% vs 15%, p<0.0001), that may contribute to the high prevalence of obesity in this group of patients. They were more frequently uncontrolled (78% vs 69%, p=0.03) and they engaged in low level physical activity (vs 80% vs 68% p≤0.001).

Conclusion: Our study gives an innovative insight into OSAS associated with severe asthma. Most of patients with OSAS belonged to the cluster “obese asthma” and none to the cluster “early onset allergic asthma”. In addition to male gender, arterial hypertension and depression, obese asthma, late onset asthma and non-atopic status were identified as specific risk factors. Oral corticosteroids seems to play a deleterious role. Phenotyping asthma can help physicians target severe asthmatic patients with OSAS and may avoid unnecessary examinations.