Olfactory impairment in COVID-19: Two methods for the assessment of olfactory function

Abstract

Background: Olfactory impairment is a major symptom of COVID-19. Is it necessary for COVID-19 patients to perform the detection of olfactory function, even how to select the olfactory psychophysical assessment tool.

Methods: Patients infected with SARS-CoV-2 Delta variant were firstly taken into three categories (mild, moderate, and severe) according to the clinical classification. The Odor Stick Identification Test for the Japanese (OSIT-J) and the Simple Olfactory Test were used to assess olfactory function. Moreover, these patients were divided into three groups based on the results of the olfactory degree (euosmia, hyposmia, and dysosmia), too. The statistical analysis of the correlations between olfaction and clinical characteristics of patients were performed.

Results: Our study demonstrated that the elderly men of Han were more susceptible to infected SARS-CoV-2, the clinical symptoms of the COVID-19 patients showed a clear correspondence with the disease type and the degree of olfactory disturbance. Whether or not to vaccinate and whether to complete the whole course of vaccination was closely related to the patient's condition. OSIT-J Test and Simple Test were consistent in our work, indicating that olfactory grading would worsen with the aggravation of symptoms. Furthermore, the OSIT-J method maybe better than Simple Olfactory Test.

Conclusion: The vaccination has an important protective effect on the general population, and vaccination should be vigorously promoted. Moreover, it is necessary for COVID-19 patients to perform the detection of olfactory function, and the easier, faster and less expensive method for determination of olfactory function should be utilized to COVID-19 patients as the vital physical examination.

Keywords: COVID-19; Coronavirus; Olfactory impairment; Physical examination; SARS-CoV-2.

Fig. 1

The relationship between olfactory test grades, vaccination, clinical types, ethnicity, sex and input ways.

Fig. 2

Error bars show olfactory test scores(A) and age(B) for mild, moderate, and severe patients and healthy controls. It represents standard error of the mean (SEM).

Fig. 3

Scatter plots show the correlation of olfactory test grades (A) and vaccination(B) for clinical type (mild, moderate, and severe patients or healthy controls).

Fig. 4

Bar plots show the fraction of sex(A), input ways(B), cough(C) and fever(D) for mild, moderate, and severe patients or healthy controls.

Fig. 5

Error bars show Leukocyte levels(A) for anosmia, hyposmia, and euosmia. Bar plots show the fraction of input ways (B), cough(C) and fever(D) for anosmia, hyposmia, and euosmia.

Fig. 6

Bar plots show the fraction of ethnicity(A), fever(B) and vaccination(C) for indigenous cases and myanmar input.

Fig. 7

Error bars show ORF1ab(A) and N(B) levels for no vaccination, one vaccination, two vaccinations.

Fig. 8

Bar plots show the fraction of sex(A), ethnicity (B), cough(C) and fever(D) for no vaccination, one vaccination, two vaccinations.

Fig. 9

The Box plot (A) shows the comparison of OSIT-J scores between patients with mild, moderate and severe groups. The point graph (B) of the correlation between olfactory identification ability (OSIT-J score) versus clinical type (mild, moderate and severe).

Fig. 10

Line charts shows trends in OSIT-J scores for mild (A), moderate (B), and severe (C) patients on day 1, 5, 10, 15, and 20 after admission.

Fig. 11

The relationship between olfactory test grades, vaccination, clinical types, ethnicity, sex and input ways.

Fig. 12

Error bars show olfactory test scores(A), age(B), weight(C), IL-6(D) and PCT(E) for mild, moderate, and severe patients or healthy controls.

Fig. 13

Scatter plots show the correlation of olfactory test grades (A) and vaccination(B) for clinical type (mild, moderate, and severe patients or healthy controls).

Fig. 14

Bar plots show the fraction of sex (A), input ways (B), ethnicity (C), cough (D) and fever (E) for mild, moderate, and severe patients or healthy controls.

Fig. 15

Error bars show CRP levels (A) for euosmia and dysosmia. Bar plots show the fraction of input ways(B), cough (C) and fever(D) for euosmia and dysosmia.

Fig. 16

Error bars show ORF1ab (A), N (B), weight(C), IgM(D), IgG(E), IL6(F) and PCT(G) levels for indigenous cases and myanmar input.

Fig. 17

Bar plots show the fraction of sex(A), cough(B), vaccination(C) and ethnicity(D) for indigenous cases and myanmar input.

Fig. 18

Error bars show olfactory test scores(A) and IgG levels(B) for no vaccination, one vaccination, two vaccinations.

Fig. 19

Bar plots show the fraction of cough(A)，fever(B) and sex(C) for no vaccination, one vaccination, two vaccinations.

Fig. 20

Box plots: (A) A comparison of Simple Olfactory Test scores between patients with mild, moderate and severe groups. (C) A comparison of Simple Olfactory Test scores between no vaccination, one vaccination and two vaccinations groups. (E) A comparison of Simple Olfactory Test scores between Han, Dai, Burman, De'ang and Jingpo groups. Point graphs: (B) A correlation of Simple Olfactory Test scores between patients with mild, moderate and severe groups. (D) A correlation of Simple Olfactory Test scores between no vaccination, one vaccination and two vaccinations groups. (F) A correlation of Simple Olfactory Test scores between Han, Dai, Burman, De'ang and Jingpo groups.

Fig. 21

Line charts shows trends in Simple Olfactory Test scores for mild (A), moderate (B), and severe (C) patients on day 1, 5, 10, 15, and 20 after admission.

Fig. 22

A receiver operating characteristic (ROC) analysis for OSIT-J Test (A) and Simple Olfactory Test (B) in mild, moderate, and severe patients and healthy controls. The area under the ROC curve of the OSIT-J Test was 0.700 for Control versus Mild group, 0.862 for Control versus Moderate group, 0.975 for Control versus Severe group, 0.628 for Mild versus Moderate group, 0.882 for Mild versus Severe group and 0.828 for Moderate versus Severe group (A), whereas that for the Simple Test was 0.831, 0.897, 0.940, 0.594, 0.750 and 0.665, respectively (B).

Fig. 23

A receiver operating characteristic (ROC) analysis for OSIT-J Test (A) and Simple Olfactory Test (B) in Myanmar input and Indigenous cases. The area under the ROC curve of the OSIT-J Test was 0.540 (A) for Myanmar input versus Indigenous cases, whereas that for the Simple Test was 0.585 (B).

Fig. 24

A receiver operating characteristic (ROC) analysis for OSIT-J Test (A) and Simple Olfactory Test (B) in no vaccination, one vaccination and two vaccinations. The area under the ROC curve of the OSIT-J Test was 0.597 for no vaccination versus one vaccination, 0.583 for no vaccination versus two vaccinations, 0.683 for one vaccination versus two vaccinations (A), whereas that for the Simple Test was 0.574, 0.704 and 0.666, respectively (B).