People with sleep apnea appear to be at higher risk of pneumonia than people without, according to a study published in the Canadian Medical Association Journal (CMAJ).

Per the report, sleep apnea is characterized by disrupted sleep, caused when the upper airway becomes obstructed by soft tissue, cutting off oxygen. It has been linked to several types of heart disease and cognitive impairment. What’s more, people with obstructive sleep apnea are at higher risk of aspiration while sleeping.

To determine whether sleep apnea is linked to the development of pneumonia, Taiwanese researchers followed 34,100 patients (6,816 who had sleep apnea and 27, 284 controls) for 11 years.

They found that pneumonia was more likely to develop in the people with sleep apnea than in the control group (638 [9.36%] versus 2,119 [7.77%]). Additionally, the study noted that the people with pneumonia were older and had more comorbidities, such as heart disease, diabetes, dementia, and other diseases.

“This study showed that sleep apnea is an independent risk factor for incident pneumonia,” writes Vincent Yi-Fong Su and Kun-Ta Chou, Department of Chest Medicine, Taipei Veterans General Hospital, Taipei, Taiwan. “Our results also demonstrated an exposure-response relation in that patients with more severe sleep apnea may have a higher risk of pneumonia than patients with sleep apnea of milder severity.”

Several studies have explored the link between sleep apnea and pneumonia, although they have been smaller than this large cohort study.

The authors suggest that the higher incidence of pneumonia in people with sleep apnea could be because of increased risk of aspirating contents or liquid from the throat.