Invalid Self-Assessment of Olfactory Functioning in Parkinson’s Disease Patients May Mislead the Neurologist
Table 1
Sociodemographic, clinical, and olfactory characteristics of the study sample.
A: sociodemographic and clinical characteristics
PD (n = 64)
HC (n = 33)
Z
value
Age (years)
64.6 ± 7.5
62.8 ± 6.3
−1.40a
0.161
Sex (M/F)
39/25
14/19
3.01 (χ2)b
0.091
Education (years)
13.8 ± 2.7
15.3 ± 2.7
−2.46a
0.014
MMSE
28.6 ± 2.0
28.8 ± 1.2
−0.71a
0.476
Geriatric Depression Scale
3.3 ± 3.0
1.3 ± 1.1
−3.27a
0.001
Apathy Evaluation Scale
11.7 ± 9.4
9.2 ± 7.0
−1.16a
0.245
Disease duration (years)
6.3 ± 5.2
—
—
—
UPDRS III
19.0 ± 10.9
—
—
—
L-Dopa equivalent daily dose (mg)
716.9 ± 387.1
—
—
—
Hoehn and Yahr stages
I: 17; II: 24; III: 20; IV: 3
—
—
—
Smoker status (smoker/former smoker/never smoker)
7/22/35
5/9/18
0.64 (χ2)b
0.714
Pack-years
9.1 ± 12.6
6.4 ± 10.6
−0.62a
0.534
B: olfactory characteristics
PD (n = 64)
HC (n = 33)
Z
value
Odor threshold test
4.8 ± 3.2
7.4 ± 2.4
−4.16a
≤0.001
Odor discrimination test
8.2 ± 2.5
11.8 ± 1.6
−6.24a
≤0.001
Odor identification test
7.5 ± 3.3
13.6 ± 1.8
−7.05a
≤0.001
TDI
20.5 ± 7.0
32.8 ± 3.9
−6.83a
≤0.001
Classification according to Hummel et al. [16] (no. of subjects)
Normosmia: 31, hyposmia: 33
Normosmia: 33, hyposmia: 0
25.79 (χ2)b
≤0.001
Olfactory self-evaluation classification (no. of subjects)
Unimpaired: 21, reduced: 43
Unimpaired: 27, reduced: 6
20.92 (χ2)b
≤0.001
Visual analogue scale
44.2 ± 23.3
61.3 ± 19.0
−3.79a
≤0.001
Data are given as mean ± standard deviation. a: Mann–Whitney U test and b: Fisher’s exact test. PD: Parkinson’s disease; HC: healthy control group; MMSE: Mini-Mental Status Examination; UPDRS: Unified Parkinson’s Disease Rating Scale; TDI: Global score of olfaction consisting of threshold, discrimination, and identification subscores of the Sniffin’ Sticks test battery.