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Mov Disord. 2016 Sep;31(9):1408-13. doi: 10.1002/mds.26637. Epub 2016 May 9.

Optimizing odor identification testing as quick and accurate diagnostic tool for Parkinson's disease.

Author information

1
Department of Neurology, Medical University Innsbruck, Innsbruck, Austria.
2
Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom.
3
Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Centre, Amsterdam, The Netherlands.
4
Divisions of Human Nutrition, Wageningen University, Wageningen, The Netherlands.
5
Study Center Confraternitaet-PKJ Vienna, Vienna, Austria.
6
Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands.
7
Department of Applied Systems Research and Statistics, Johannes Kepler University Linz, Linz, Austria.
8
Department of Medical Statistics, Informatics and Health Economics, Medical University Innsbruck, Innsbruck, Austria.
9
Department of Neurology, Hospital of Bruneck, Bruneck, Italy.
10
Department of Neurology, Medical University Innsbruck, Innsbruck, Austria. klaus.seppi@uki.at.

Abstract

INTRODUCTION:

The aim of this study was to evaluate odor identification testing as a quick, cheap, and reliable tool to identify PD.

METHODS:

Odor identification with the 16-item Sniffin' Sticks test (SS-16) was assessed in a total of 646 PD patients and 606 controls from three European centers (A, B, and C), as well as 75 patients with atypical parkinsonism or essential tremor and in a prospective cohort of 24 patients with idiopathic rapid eye movement sleep behavior disorder (center A). Reduced odor sets most discriminative for PD were determined in a discovery cohort derived from a random split of PD patients and controls from center A using L1-regularized logistic regression. Diagnostic accuracy was assessed in the rest of the patients/controls as validation cohorts.

RESULTS:

Olfactory performance was lower in PD patients compared with controls and non-PD patients in all cohorts (each P < 0.001). Both the full SS-16 and a subscore of the top eight discriminating odors (SS-8) were associated with an excellent discrimination of PD from controls (areas under the curve ≥0.90; sensitivities ≥83.3%; specificities ≥82.0%) and from non-PD patients (areas under the curve ≥0.91; sensitivities ≥84.1%; specificities ≥84.0%) in all cohorts. This remained unchanged when patients with >3 years of disease duration were excluded from analysis. All 8 incident PD cases among patients with idiopathic rapid eye movement sleep behavior disorder were predicted with the SS-16 and the SS-8 (sensitivity, 100%; positive predictive value, 61.5%).

CONCLUSIONS:

Odor identification testing provides excellent diagnostic accuracy in the distinction of PD patients from controls and diagnostic mimics. A reduced set of eight odors could be used as a quick tool in the workup of patients presenting with parkinsonism and for PD risk indication. © 2016 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

KEYWORDS:

Parkinson's disease; diagnosis; olfactory dysfunction; parkinsonism; tremor

PMID:
27159493
PMCID:
PMC5026160
DOI:
10.1002/mds.26637
[Indexed for MEDLINE]
Free PMC Article

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