### INTRODUCTION

### MATERIALS AND METHODS

### Study design and participants

### YOF test protocol

#### Odor thresholds test (T)

#### Odor discrimination test (D)

#### Odor identification test (I)

### Test protocol for KVSS-II

### Optimization of cutoff criteria for the YOF test

#### Cutoff for anosmia

#### Cutoff for hyposmia

### Statistical analyses

*t*-test. IBM SPSS ver. 25.0 (IBM Corp., Armonk, NY, USA) was for statistical analysis of independent samples

*t*-test, one-way ANOVA, Mann-Whitney

*U*-test, logistic regression test, and Pearson coefficient correlation. MedCalc software ver. 14.8.1 (MedCalc Software, Mariakerke, Belgium) was used to assess the cutoff points of TDI score of the YOF test and KVSS-II for anosmia and hyposmia and compare their AUC.

*P*<0.05 indicated statistical significance.

### RESULTS

### Demographic data and mean olfactory function test scores

*P*<0.001 with the Pearson chi-square test). The rate of anosmia was higher in females, but this difference was not significant (

*P*=0.069). Mean age was significantly higher in the anosmia group than in the other groups (normosmia group, 47.0±16.9 years; hyposmia group, 49.6±16.3 years; anosmia group, 52.9±14.1 years;

*P*<0.001, with one-way ANOVA). According to the post hoc Tukey analysis, significant differences were found between the mean age of the normosmia group and that of the hyposmia (

*P*=0.031) and anosmia groups (

*P*<0.001), but not between the mean age of the hyposmia group and the anosmia group (

*P*=0.131). The mean values of each T/D/I subtest and the total TDI scores among the normosmia, hyposmia, and anosmia groups were significantly different in both the YOF test and KVSS-II (

*P*<0.001).

### Comparison between the YOF test and KVSS-II in the normosmia group

^{2}=0.031,

*P*<0.001), discrimination (β=–0.046, R

^{2}=0.088,

*P*<0.001), identification (β=–0.046, R

^{2}=0.060,

*P*<0.001), and total TDI score (β=–0.115, R

^{2}=0.081,

*P*<0.001) consistently showed significant negative correlations with age in the logistic regression analysis. For greater clarity, the distribution of the YOF test and KVSS-II scores (total TDI score and T/D/I subtest scores) in the normosmia group were graphically expressed through the score ratio (0 to 1, test score/score scale) (Supplementary Fig. 1).

#### Threshold

*P*<0.001) (Supplementary Fig. 1). This statistical difference was caused by differences in the content of each olfactory function test (e.g., test odorant, concentration, score scales, etc.).

#### Discrimination

*t*=0.23,

*P*=0.820) (Supplementary Fig. 1).

#### Identification

*P*=0.214, Mann-Whitney

*U*-test). The mean I score on the YOF test for the normosmia group was 11.1±1.7 on a 12-point scale, whereas that for the KVSS-II was 12.1±2.3 on a 16-point scale (Table 4). For the identification test, the YOF test (mean, 0.92; SEM, 0.01) showed a significantly higher mean score ratio than the KVSS-II (mean, 0.76; SEM, 0.01;

*P*<0.001) (Supplementary Fig. 1).

#### Total TDI score

*P*<0.001) (Supplementary Fig. 1).

### Optimized diagnostic cutoff of the YOF test and comparison with the KVSS-II

#### Cutoff of total TDI score for anosmia

*P*=0.843).

#### Cutoff of total TDI score for hyposmia

*P*=0.902).

### Correlations between the YOF test and the KVSS-II

*r*) between the YOF test and the KVSS-II was

*r*=0.57 for the T test,

*r*=0.65 for the D test,

*r*=0.80 for the I test, and

*r*=0.86 for the total TDI score (

*P*<0.001, respectively). The total TDI scores showed a higher correlation between the YOF test and the KVSS-II than any of the T/D/I subtest scores.