Olfactory disorders in COVID-19 patients as a prognostic factor: a systematic review

The Egyptian Journal of Otolaryngology

Table 1 The characteristics of included studies

Authors	Type of study	Country	Study period	Sample size	Sex	Age	In or outpatients	Anosmia	Taste loss	Both disorders	Death—anosmia	Death—taste loss	ICU—taste loss	ICU—anosmia	Intubation—anosmia	Intubation—taste loss	NOS—scale	Quality
Amanat (2021) [20]	Retrospective cohort	Iran	112	873	Both	60.71	Hospitalized	232	561	561	65						********	High
Avcı (2020) [21]		Turkey	40	1534	Both	39.44	Both	529	300								********	High
Etessam (2021)		Spain		5868	Both	64.2	Both	377	404	505	1079			303			*******	High
Petrocelli (2020) [23]		Italy	18	300	Both	43.6	Both	141	20	164	0	0		27	0	0	********	High
Talavera (2020) [24]		Spain	35	576	Both	67.2	Hospitalized	146			5						********	High
Yan (a) (2020) [25]		USA	36	169	Both	53.3	Both	7				3			0		*********	High
Vaira (2020) [26, 30]		England	20	106	Both	49.6	Both	44			0	0					*******	High
Carignan (2020) [27]		Canada	14	268	Both	57.1	Both	69	68		0	0			0	0	*********	High
Yan (2020) [25]	Cross-sectional	USA	23	262	Both	45	Hospitalized	40			0	0	0	0	0		********	High
Corbellini (2020) [28]	Cross-sectional	Spain	10	79	Both	61.6	Both	14	50	31	0	0			5		********	High