Mounting evidence suggests there is a strong relationship between asthma and obstructive sleep apnea (OSA), whereby each disorder deleteriously influences the other. However, little is known regarding which condition leads to the other. Understanding the initiating processes of the potentially self-reinforcing asthma–OSA cycle could help reduce the burden of both conditions.

Asthma & OSA: Chicken or the Egg?

For a study published in JAMA, Mihaela Teodorescu, MD, MS, and colleagues examined the asthma–OSA relationship among a cohort of patients without OSA at baseline. Self-reported asthma and asthma duration were recorded beginning in 1988, and laboratory-based sleep studies were conducted every 4 years through 2013. “We followed the incidence of OSA in asthmatics versus non-asthmatics,” says Dr. Teodorescu.

The study team found that asthma increased the risk of OSA development at 4 years by about 40%. At the first 4-year follow-up, 27% of patients with asthma experienced incident OSA, compared with a 16% rate among those without asthma. Similar rates of OSA were observed when looking across the full study period. The researchers found the association between OSA and asthma was not significantly affected by:

♦  Baseline and 4-year changes in BMI, neck or waist girth, or waist-to-hip ratio.

♦  Menopausal status.

♦  Asthma controller use.

♦  The availability of follow-up polysomnography.

“Our findings suggest that asthma most likely leads to the development of OSA, regardless of the presence of predisposing factors for sleep apnea,” adds Dr. Teodorescu. The researchers added that the longer patients had suffered from asthma, the higher their likelihood was of developing OSA. “This has important implications for younger populations because asthma starts to develop during the first year of life in many cases, particularly among boys,” explains Dr. Teodorescu. “In addition, sleep apnea is more common in males.”

Next Steps With Asthma Patients

Clinicians should regularly ask patients with asthma about sleep apnea symptoms, says Dr. Teodorescu. “Sleepiness and lack of energy can be symptoms of both asthma and sleep apnea, but snoring and a history of pauses in breathing during sleep are signs of sleep apnea,” she says. “If they are suspicious of OSA, patients should be referred for a sleep study. It’s also important to make patients aware that having trouble breathing at night may not only be caused by asthma; it could also be due to OSA.”

Dr. Teodorescu stresses the importance of future investigations into how the OSA–asthma relationship evolves across the age spectrum. “To make progress on how to effectively mitigate the risk of asthmatics developing OSA,” she says, “we also need research to better understand the mechanisms underlying this relationship.”