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	−1.40^a	0.161
Sex (M/F)	39/25	14/19	3.01 (χ^2)^b	0.091
Education (years)	13.8 ± 2.7	15.3 ± 2.7	−2.46^a	0.014
MMSE	28.6 ± 2.0	28.8 ± 1.2	−0.71^a	0.476
Geriatric Depression Scale	3.3 ± 3.0	1.3 ± 1.1	−3.27^a	0.001
Apathy Evaluation Scale	11.7 ± 9.4	9.2 ± 7.0	−1.16^a	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 (χ^2)^b	0.714
Pack-years	9.1 ± 12.6	6.4 ± 10.6	−0.62^a	0.534
B: olfactory characteristics
	PD (n = 64)	HC (n = 33)	Z	value
Odor threshold test	4.8 ± 3.2	7.4 ± 2.4	−4.16^a	≤0.001
Odor discrimination test	8.2 ± 2.5	11.8 ± 1.6	−6.24^a	≤0.001
Odor identification test	7.5 ± 3.3	13.6 ± 1.8	−7.05^a	≤0.001
TDI	20.5 ± 7.0	32.8 ± 3.9	−6.83^a	≤0.001
Classification according to Hummel et al. [16] (no. of subjects)	Normosmia: 31, hyposmia: 33	Normosmia: 33, hyposmia: 0	25.79 (χ^2)^b	≤0.001
Olfactory self-evaluation classification (no. of subjects)	Unimpaired: 21, reduced: 43	Unimpaired: 27, reduced: 6	20.92 (χ^2)^b	≤0.001
Visual analogue scale	44.2 ± 23.3	61.3 ± 19.0	−3.79^a	≤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.