TABLE III.
Baseline Characteristics for Aggregate Studies (Diagnosis and Assessment of Olfactory Dysfunction).
| Study | Type of OD | Olfactory Dysfunction Diagnosis | Objective Olfactory Assessment Scores | Duration of OD (days) | |
|---|---|---|---|---|---|
| Study Group | Control Group | ||||
| Güney (2021) | Hyposmia (n = 38); anosmia (n = 3) | Visual analog scale (VAS) | Mean VAS: 3.39 ± 1.46 | NR | NR |
| Lechien (2020) | Anosmia (n = 16) | Sinonasal outcome test 22 (SNOT‐22); Questionnaire of Olfactory Disorders‐Negative Statements (sQOD‐NS); Sniffin' Sticks score | Mean Sniffin' Sticks score: 4.6 ± 1.7 | NR | NR |
| Eliezer (2020) | Not specified | Visual olfactive score (VOS) |
VOS—mean: 1.6 ± 1.9; range: 0–6 Olfactory score—mean: 2.8 ± 2.7; range: 0–8 |
Olfactory score—mean: 9.4 ± 0.7; range: 8–10 | NR |
| Chetrit (2020) | Hyposmia (n = 19); anosmia (n = 4) | National Health and Nutrition Examination Survey (NHNES)—smell and taste component; Sniffin' Sticks tests | Mean Sniffin' Sticks score: 3.2 ± 4.4 | 9.6 ± 6.9 | |
| Shor (2021) | Anosmia (n = 10) | NR | NR | NR | NR |
| Chung (2021) | Anosmia (n = 2) | Sinonasal outcome test (SNOT‐22); butanol threshold test (BTT); smell identification test (SIT) | NR | NR | NR |
| Tsivgoulis (2021) | Microsmia (n = 6); anosmia (n = 2) | Self‐reporting; three‐odorant test Quick Smell Identification TestTM (Q‐SITTM); sinonasal outcome test 22 (SNOT 22) questionnaire | NR | NR | NR |
| Kandemirli (2021) | Anosmia (n = 23) | Sniffin' Sticks test battery | Median threshold score: 1 (IQR 1–2.25); median discrimination score: 2 (IQR 0–3); median identification score: 2 (IQR 0–4); median TDI score: 4 (IQR 1–8.5) | NR | NR |
| Altundag (2021) | Anosmia (n = 62) | Clinical history; Four‐item odor identification test in COVID‐19 anosmia patients; Sniffin' Sticks olfactory test for all participants |
Four‐item odor identification test Mean score: 0 Sniffin' Sticks tests Mean‐threshold (t) value: 1.2 ± 0.5; Discrimination (d): 0.9 ± 1; Identification (i): 1.4 ± 2; Total TDI score: 3.6 ± 3.3; Mean TDI score: 3.60 |
Sniffin' Sticks tests Anosmia due to viral infection other than COVID‐19—Mean t value: 1.7 ± 2; d value: 1.5 ± 1.7; i value: 2.3 ± 2.7; Total TDI score: 5.5 ± 5.1; Mean TDI score: 4.54 Healthy controls—Mean t value: 11 ± 1; d value: 12.5 ± 1.5; i value: 13.3 ± 0.7; Total TDI: 35 ± 2.3; Mean TDI score: 38.07 |
NR |
| Yıldız (2021) | Mild hyposmia (n = 13); moderate hyposmia (n = 13); severe hyposmia (n = 9); anosmia (n = 5) | Connecticut Chemosensory Clinical Research Center (CCCRC) olfactory test | Mild hyposmia (n = 13); moderate hyposmia (n = 13); severe hyposmia (n = 9); anosmia (n = 5) | NR | NR |
| Naeini (2020) | Anosmia | NR | NR | NR | NR |
| Niesen (2021) | Hyposmia (n = 5); Anosmia (n = 7) | Identification test included in Sniffin' Sticks battery; qualitative anamnesis and visual analog scale | Sniffin' Sticks identification test: Mean identification test score: 8/16 (± 1.4); Documented hyposmia (scores between 9 and 11): 5 individuals; Documented anosmia (score ≤8): 7 individuals | NR | NR |
NR = not reported; OD = olfactory dysfunction; TDI = threshold discrimination identification.