Coronavirus disease 2019 and obstructive sleep apnea syndrome.

Dear Editor

The publications regarding the continuing of pandemic coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are increasing. Increased age, hypertension, cardiovascular diseases, lung diseases, and diabetes mellitus seem to be the main risk factors for mortality in COVID-19 [1]. However, the possible association between obstructive sleep apnea syndrome (OSAS), repetitive airway collapse with apnea/hypopnea and hypoxia during sleep, and COVID-19 has not been reported yet.

Angiotensin converting enzyme 2 (ACE2) is the entry receptor of SARS-CoV-2 [2]. Of note, the increased expression of ACE and dysregulation of renin angiotensin system in untreated OSAS patients due to chronic intermittent hypoxia has been shown [3]. Furthermore, cardiovascular complications or comorbidities such as hypertension, heart failure, coronary artery disease, cerebrovascular diseases, diabetes mellitus, and obesity—those are also risk factors for mortality in COVID-19—are commonly seen in OSAS patients [1, 4]. Fibrotic changes can also be seen after COVID-19 [5] and fibrosis was peviously shown to be a risk factor for OSAS.

To the best of our knowledge, this is one of the first reports highlighting the possible association between OSAS and COVID-19. Herewith, presenting this clinical perspective is two-fold. First, OSAS may be a risk factor for mortality or deteriorate the clinical scenario in COVID-19. Therefore, keeping in mind the modulating effects of sleep on the immune system, proper treatment of OSAS patients may be protective/beneficial in COVID-19. Second, patients who suffered from COVID-19, particularly severe cases, may be under risk for OSAS due to pulmonary fibrosis. Clinicians should be cautious against the OSAS presence during the later periods in relevant patients.