MedWire News: Obstructive sleep apnea–hypopnea (OSAH) is significantly more common among patients with asthma than those without the condition, and among asthma patients significantly more common with severe than with moderate disease, Canadian researchers have found.

“The results suggest a potentially important link between asthma control and OSAH,” comment R John Kimoff (McGill University Health Centre, Montreal, Quebec) and colleagues.

The team assessed the prevalence of OSAH among 26 patients with severe asthma, 26 patients with moderate asthma, and 26 controls without asthma using complete overnight polysomnography. The participants were of similar age and body mass index.

Using Chicago criteria, which defines OSAH as an Apnea–Hypopnea Index of at least 15 events per hour of sleep, 88% of patients with severe asthma had OSAH, compared with just 58% of those with moderate asthma and 31% of controls.

Using more restrictive criteria from the Wisconsin cohort study, OSAH was present in 50% of patients with severe asthma, 23% with moderate asthma, and 12% of controls.

Average nocturnal arterial oxygen saturation levels were significantly lower in patients with severe asthma than controls, and the average severity of OSAH was significant worse for patients in both asthma groups than controls.

Kimoff and team conclude in the Journal of Allergy and Clinical Immunology: “The very high prevalence of obstructive sleep apnea–hypopnea among patients with severe asthma suggests that recognition and treatment of sleep apnea may be an important element in improving asthma control.”

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