Results
Between March 2020 and March 2021, 20 healthy volunteers were included
in the study. Characteristics of the volunteers are described in Table
1.
Intra-group comparison
In group 1 and 2, all the subjects were normosmic without a mask, except
for two subjects who were hyposmic (Table 2). The two hyposmic subjects
(respectively 49 and 52 years old) had a TDI of 28.5 for subject 1 and
27.5 for subject 2.
All the subjects, except one, experienced a significant decreased
olfactory performance when wearing a mask (p=0.02) (Figure 1).
The average difference observed with and without a mask were inferior to
5 for both group 1 and 2 (respectively 3.77 and 4.87), being
non-clinically relevant. Nevertheless, 8 participants (40%, 35±13 years
old) had a TDI difference with and without a mask superior to 5. Among
them, four participants (one in group 1 and 3 in group 2, 38±19 years
old) were normosmic without a mask (TDI superior to 30.5, average TDI of
34.9±1.1), while being recategorized as hyposmic with a mask (TDI
inferior to 30, average TDI of 27.8±0.6). For the 4 other participants
with a TDI difference with and without mask superior to 5 (average TDI
difference of 6.25±1.2, 33±6 years old), they were normosmic with and
without a mask: average TDI of 35.3±1.6 and 41.6±1.1 respectively.
The identification test appeared to be the less impacted sub-test when
wearing a mask (Table 2). The difference in threshold tests with and
without a mask was greater in group 2 than in group 1 (2,08 and 1,48
respectively), but without clinically impact (difference in
T-score<2.5). The difference in discrimination test with and
without a mask was greater in group 2 than in group 1 (3,3 and 1,9
respectively), with only clinical significance in group 2 (difference in
D-score>3).
Inter-group comparison
The differences in average total scores between group 1 and 2 were
compared using a Mann Whitney Test and were not statistically
significant (p=0.57).