Researchers have found that people who have been diagnosed with obstructive sleep apnoea could be at increased risk of adverse outcomes from Covid-19.

The conclusion was drawn from a systematic review of studies that reported outcomes for Covid-19 patients that were also diagnosed with obstructive sleep apnoea. Published in the journal Sleep Medicine Reviews, the review highlights the need to further investigate the impact of the virus on those with the sleep condition and to better identify those currently undiagnosed with it.

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Many of the risk factors and co-morbidities associated with sleep apnoea, such as diabetes, obesity and hypertension, are similar to those associated with poor Covid-19 outcomes. However, the researchers wanted to investigate whether being diagnosed with obstructive sleep apnoea conferred an additional risk on top of those factors.

“It is likely that Covid-19 increases oxidative stress and inflammation and has effects on the bradykinin pathways, all of which are also affected in obstructive sleep apnoea patients,” said study lead author Michelle Miller from the University of Warwick in the UK.

“When you have individuals in which these mechanisms are already affected, it wouldn’t be surprising that Covid-19 affects them more strongly.” Miller added. The systematic review looked at 18 studies up to June 2020 with regards to obstructive sleep apnoea and Covid-19, of these eight were mainly related to the risk of death from Covid-19 and 10 were related to diagnosis, treatment and management of sleep apnoea.

Although few studies of obstructive sleep apnoea in Covid-19 had been performed at the time, there is evidence to suggest that many patients who were presented to intensive care had obstructive sleep apnoea and in diabetic patients, it may confer an increased risk that is independent on other risk factors.

In one large study in patients that had diabetes and who were hospitalised for COVID-19, those being treated for obstructive sleep apnoea were at 2.8 times greater risk of dying on the seventh day after hospital admission. With obesity rates and other related risk factors on the increase, the researchers also believe that rates of obstructive sleep apnoea are also increasing.

The review highlights that the pandemic has also had worldwide effects on the ongoing diagnosis, management and treatment of patients with this and other sleep conditions.