Greater Airway Collapsibility in Chinese Vs. Caucasian OSA Patients

By Anne Harding

September 25, 2019

NEW YORK (Reuters Health) - Chinese patients with obstructive sleep apnea (OSA) have more collapsible pharyngeal airways and less ventilatory-control instability than Caucasian patients with the sleep disorder, new research shows.

"Physicians should take into consideration that OSA in their Chinese patients is likely to be driven by a small, collapsible upper airway, and as such this may impact treatment pathways," Dr. Denise O'Driscoll of Eastern Health Clinical School at Monash University in Melbourne, Australia, told Reuters Health in an email.

"Our study suggests that the most effective treatments will likely be those that improve upper-airway anatomical predisposition (for example, oral appliances, weight loss, surgery, positional therapy)," she added.

Studies linking OSA and elevated BMI have been done mainly in Caucasians, Dr. O'Driscoll and her team note in Sleep, online August 16. While the prevalence of OSA is similar among Caucasian and Chinese individuals, they add, Chinese patients with the same disease severity have lower BMIs.

Given that anatomical differences that may promote OSA have been identified in Chinese individuals, Dr. O'Driscoll and her team compared upper airway anatomy and non-anatomic factors in 45 Caucasian and 45 Chinese patients with moderate to severe OSA matched by age and apnea hypopnea index (AHI).

Caucasian patients were heavier and had higher BMIs than the Chinese study participants.

The Chinese participants had greater upper-airway collapsibility compared to the Caucasians (Vpassive - the ventilatory equivalent of the critical pharyngeal collapsing pressure - was 68.9% vs. 74%; P=0.012). Forty Chinese individuals had high collapsibility, versus 31 Caucasians.

Chinese study participants also had significantly lower loop gain than Caucasians (0.60 vs. 0.63). Loop gain is the amount of increased ventilatory drive in response to previous reduction in ventilation, and is an indicator of ventilatory-control-system sensitivity.

Muscle compensation and arousal threshold were similar for the two groups.

Pharyngeal collapsibility was the only independent predictor of OSA severity in both Chinese and Caucasian participants.

"Our future research will focus on the clinical outcomes of treatment of OSA in Chinese patients," Dr. O'Driscoll said. "Adherence to different treatments, as well as any improvements in cardiovascular measures and daytime sleepiness will be key features."


Sleep 2019.