. 2021 Nov 9;16(11):e0259321. doi: 10.1371/journal.pone.0259321

Table 3. Study characteristics of studies that used objective and subjective olfactory measures.

First Author, Year	Country	Sample Size	Age (years) (mean/median* (SD)	COVID-19 Disease Severity	Olfactory Assessment Tool	Initial Smell Function
						Anosmia	Hyposmia	Normosmia
						%	%	%
Cohort Studies
Bertlich, 2021 [57]	Europe (Germany)	23	59.0 (16.6)	Mild-Moderate	BSIT	72.70%	27.3%	0%
					SNOT-22
					VAS
Lechien, 2021 [58]	Europe	233(Objective). 1363(Subjective).	44.5 (16.4)	Mild-Moderate	Sniffin’ Sticks	32.20%	18.40%	49.40%
Lechien, 2021 [58]	Europe	233(Objective). 1363(Subjective).	44.5 (16.4)	Mild-Moderate	SNOT-22	32.20%	18.40%	49.40%
Iannuzzi, 2020 [59]	EU (Italy)	34	47.47 (13)	Mild-Moderate	Sniffin’ Sticks, VAS	10%	53.30%	36.70%
Iannuzzi, 2020 [59]	EU (Italy)	34	47.47 (13)	Mild-Moderate	HRS	10%	53.30%	36.70%
Lechien, 2020 [60]	EU (Belgium)	88	42.6 (11.2)	Mild-Moderate	Sniffin’ Sticks SNOT-22,	40%	35%	25%
Lechien, 2020 [60]	EU (Belgium)	88	42.6 (11.2)	Mild-Moderate	sQOD-NS, NHANES (smell/taste components), tests	40%	35%	25%

SD = Standard Deviation; RT-PCR = Reverse Transcription–Polymerase Chain Reaction; BSIT = The Brief Smell Identification Test; VAS = Visual Analogue Score; SNOT-22 = Sino-nasal Outcome Test-22; HRS = Hyposmia Rating Scale; sQOD-NS = short version of the Questionnaire of Olfactory Disorders-Negative Statements; NHANES = National Health and Nutrition Examination Survey.