Hypoxic burden implementation

[boupetch]

The ‘hypoxic burden’, an easily derived signal from overnight sleep study, predicts CVD mortality across populations.
It could be very useful to implement this variable in sleepr.
This is the paper published in November 2018.

Azarbarzin A, Sands SA, Stone KL, Taranto-Montemurro L, Messineo L, Terrill PI, et al. The hypoxic burden of sleep apnoea predicts cardiovascular disease-related mortality: the Osteoporotic Fractures in Men Study and the Sleep Heart Health Study. Eur Heart J [Internet]. [cited 2018 Dec 7]; Available from: https://academic.oup.com/eurheartj/advance-article/doi/10.1093/eurheartj/ehy624/5146754