Prevalence of obstructive sleep apnea–hypopnea in severe versus moderate asthma

BackgroundPrevious studies have suggested a link between obstructive sleep apnea and poor asthma control, which may be mediated through airway inflammation, obesity, and other mechanisms.ObjectiveTo test the hypothesis that the prevalence and severity of sleep apnea is greater among patients with severe compared with moderate asthma and controls without asthma.MethodsComplete overnight home polysomnography was performed in 26 patients with severe asthma consecutively recruited to a difficult asthma program, 26 patients with moderate asthma, and 26 controls without asthma of similar age and body mass index. Flow rates and Juniper asthma control and quality of life questionnaires were also obtained.ResultsObstructive sleep apnea–hypopnea, defined by an Apnea–Hypopnea Index ≥15 events/h of sleep scored using Chicago criteria, was present in 23 of 26 (88%) patients with severe asthma, 15 of 26 (58%) patients with moderate asthma, and 8 of 26 (31%) controls without asthma (χ2: P < .001). Using the more restrictive scoring criteria applied in the Wisconsin cohort study, Apnea-Hypopnea Index ≥5/h was present in 50% (severe), 23% (moderate), and 12% (control) of subjects (P = .007). Mean nocturnal arterial oxygen saturation was significantly lower in patients with severe asthma versus controls, and apnea-hypopnea severity measures were significantly worse for both asthmatic groups compared with controls. Among subjects with asthma, no significant correlations were identified between the severity of sleep-disordered breathing and asthma severity or control measures (FEV1, Juniper scores).ConclusionsObstructive sleep apnea–hypopnea was significantly more prevalent among patients with severe compared with moderate asthma, and more prevalent for both asthma groups than controls without asthma. These observations suggest potential pathophysiologic interactions between obstructive sleep apnea–hypopnea and asthma severity and control.