Almost all patients with both obstructive sleep apnea syndrome and severe asthma fell into the obesity phenotype, not the allergy phenotype, based on data from nearly 1,500 adults.
Both asthma and sleep-disordered breathing are common conditions worldwide, and previous research suggests that obstructive sleep apnea syndrome (OSAS) and severe asthma in particular could be associated, wrote Laurent Portel, MD, of Centre Hospitalier de Libourne, France, and colleagues.
“Even if the underlying mechanisms are not well established, it is clear that both OSAS and obesity act to aggravate existing asthma, making it more difficult to control,” they said. However, the pathology of this relationship is not well-understood, and data on severe asthma phenotypes and OSAS are limited, they said.
In a study published in Respiratory Medicine and Research, the investigators reviewed data from 1,465 patients older than 18 years with severe asthma who were part of a larger, prospective multicenter study of the management of asthma patients. The larger study, developed by the Collège des Pneumologues des Hôpitaux Généraux (CPHG) is known as the FASE-CPHG (France Asthme SEvère-CPHG) and includes 104 nonacademic hospitals in France.
Diagnosis of OSAS was reported by physicians; diagnosis of severe asthma was based on the Global Initiative for Asthma criteria. The average age of the patients was 54.4 years, 63% were women, and 60% were nonsmokers.
A total of 161 patients were diagnosed with OSAS. The researchers conducted a cluster analysis on 1,424 patients, including 156 of the OSAS patients. They identified five clusters: early-onset atopic asthma (690 patients), obese asthma (153 patients), late-onset asthma (299 patients), eosinophilic asthma (143 patients), and aspirin sensitivity asthma (139 patients).
All 153 patients in the obese asthma cluster had OSAS, by contrast, none of the patients in the early atopic asthma cluster had OSAS.
Overall, obesity, male sex, high blood pressure, depression, late-onset asthma, and early-onset atopic asthma were independently associated with OSAS, with odds ratios of 5.782, 3.047, 2.875, 2.552, 1.789, and 0.622, respectively.
Notably, OSAS patients were more frequently treated with long-term oral corticosteroids than those without OSAS (30% vs. 15%, P < .0001), the researchers said. “It is possible that this treatment may be responsible for obesity, and it represents a well-known risk factor for developing OSAS,” they wrote.
Uncontrolled asthma was significantly more common in OSAS patients than in those without OSAS (77.7% vs. 69%, P = .03), and significantly more OSAS patients reported no or occasional physical activity (79.8% vs. 68.2%, P ≤ .001).
The study findings were limited by several factors including the lack of patients from primary care or university hospitals, which may limit the generalizability of the results, the reliance on physician statements for diagnosis of OSAS, and the lack of data on OSAS severity or treatment, the researchers noted.
However, the results fill a needed gap in the literature because of the limited data on severe asthma patients in real life, and identifying severe asthma patients by phenotype may help identify those at greatest risk for OSAS, they said.
“Identified patients could more easily benefit from specific examinations such as poly(somno)graphy and, consequently, could benefit from a better management of both asthma and OSAS,” they emphasized.
The larger FASE-CPHG study was supported in part by ALK, AstraZeneca, Boehringer Ingelheim, GSK, and Le Nouveau Souffle. The researchers had no financial conflicts to disclose.