Prevalence and Outcomes of COVID −19 Patients with Happy Hypoxia: A Systematic Review

Figures & data

Figure 1 Prisma Flow chart of study selection.

Table 1 Study Characteristics of COVID-19 Patients with Happy Hypoxia

First Author	Country	Study Design	Sample Size	Year	Happy Hypoxia Definition	Study Location	Study Center	Study Period
Bepouka^Citation16	DRC	Retrospective cohort	141	2021	SpO2 < 90%, without dyspnea	DRC	Single-center	2020
Alhusain^Citation13	Saudi Arabia	Retrospective cohort	195	2021	SpO2 < 90% without dyspnea	Saudi Arabia	Single-center
Brouqui^Citation11	France	Retrospective cohort	1712	2020	SpO2 < 95%,	France	Single-center	2020
					Pa O2 ≤ 80 mmHg and PCO2 ≤35 mmHg without dyspnea,
Sirohiya^Citation14	India	Retrospective cohort	811	2021	SpO2 < 94%	India	Single-center	2021
Busana^Citation12	Italy	Retrospective cohort	213	2021	PaO2/Fi02 < 300 mm Hg, without dyspnea	Italia	Single-center
Akiyama^Citation10	Japan	Retrospective cohort	21,544	2021	SpO2≤ 93%, without dyspnea	Japan	Nationwide Japanese registration	January 1, 2020, and March 31, 2021
Garcia-Grimshaw^Citation15	Mexique	Prospective cohort study	470	2021	SpO2≤ 80%, without dyspnea	Mexico	1 Single-center	2020

Abbreviations: spO2, oxygen saturation; PaO2/FiO2, the ratio of arterial oxygen partial pressure to fractional inspired oxygen.

Table 2 Prevalence of Happy Hypoxia in COVID-19

First Author	Study Location	Happy Hypoxia Definition	Subjects N	Subjects with Happy Hypoxia	Prevalence
Bepouka^Citation16	DRC	SpO2 < 90%, without dyspnea	141	9	6.4
Alhusain^Citation13	Saudi Arabia	SpO2 < 90% without dyspnea	195	25	13
Brouqui^Citation11	France	SpO2 < 95%,	1712	1107	65
		Pa O2 ≤ 80 mmHg and PCO2 ≤35 mmHg without dyspnea,
Sirohiya P^Citation14	India	SpO2 < 94%	811	174	21.5
Busana^Citation12	Italy	PaO2/Fi02 < 300 mm Hg, without dyspnea	213	68	31.9
Akiyama Y^Citation10	Japan	SpO2≤ 93%, without dyspnea	21,544	1035	4.8
Garcia-Grimshaw^Citation15	Mexico	SpO2≤ 80%, without dyspnea	470	23	4.8

Abbreviations: spO2, oxygen saturation; PaO2/FiO2, the ratio of arterial oxygen partial pressure to fractional inspired oxygen.

Figure 2 Pooled Prevalence of happy hypoxia in COVID-19 patients.

Table 3 Mortality of Patients with Happy Hypoxia

First Author	Subjects with Happy Hypoxia	Died	Mortality Rate
Bepouka^Citation16	9	4	44
Alhusain^Citation13	25	2	8
Brouqui^Citation11	1107	11	1
Sirohiya P^Citation14	174	79	45.4
Busana^Citation12	68	37	17.6
Akiyama Y^Citation10	1035	88	8.5
Garcia-Grimshaw^Citation15	23	7	30.4

Figure 3 Pooled mortality rate of patients with happy hypoxia.

Table 4 Other Outcomes of Patients with Happy Hypoxia

First Author	Outcome	Happy Hypoxia	Dyspnea	p-Value
Alhusain^Citation13		N=25	N=170
	ICU admission	9(36%)	107(64)	0.007
	Intubation	3(12)	63(37)	0.013
	ICU length of the day
	<4	2(22)	16(15)	0.783
	4–7	3(33)	25(23)
	8–13	2(22)	29(27)
	>14	2(22)	37(35)
Brouqui^Citation11		N=1107	N=605
	Transfert to ICU	16(1.4)	31(5.1)	<0.001
	Transfert to ICU and /or death	23(2.1)	44(7.3)	<0.001
Busana^Citation12	Transfert
	To the ICU	26.50%	38.60%	0.082
Akiyama^Citation10
	No oxygen therapy	284(27.4)	16,737(81.6)	NA
	Oxygen therapy 751(72.6)		3767(18.4)
	ECMO	57(5.1)	221(1)
Study	Outcome	Happy hypoxia	Dyspnea	P-value
Garcia-Grimshaw^Citation15		N=23	N=447
	Invasive mechanical ventilation n (%)	6(26.1)	166(37.1)	0.376
	Days of in-hospital stay, median (IQR)	7(4–13)	7(2–15)	0.86

Abbreviations: ECMO, extracorporeal membrane oxygenation; ICU, intensive care unit; IQR, interquartile range; NA, not applicable.

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