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Open Access Research article

The odor stick identification test for Japanese differentiates Parkinson's disease from multiple system atrophy and progressive supra nuclear palsy

Masahiko Suzuki1*, Masaya Hashimoto1, Masayuki Yoshioka1, Maiko Murakami1, Keiichi Kawasaki1 and Mitsuyoshi Urashima2

Author Affiliations

1 Department of Neurology, Aoto Hospital, Jikei University School of Medicine, 6-41-2 Aoto Katsushika-ku, Tokyo 125-8506, Japan

2 Division of Molecular Epidemiology, Jikei University School of Medicine, 3-25-8 Nishi-shimbashi, Minato-ku, Tokyo 105-8461, Japan

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BMC Neurology 2011, 11:157  doi:10.1186/1471-2377-11-157

Published: 22 December 2011

Abstract

Background

Progressive supranuclear palsy (PSP) and parkinsonian variant of multiple system atrophy (MSA-P) are clinically difficult to differentiate from idiopathic Parkinson's disease (PD), particularly in the early stages of the disease. Previous reports indicated that the olfactory function is relatively intact or slightly reduced in patients with PSP and MSA-P, suggesting that the odor stick identification test for Japanese (OSIT-J), which is a short and simple noninvasive test that is potentially useful clinically for detecting early-stage PD in Japan, may be useful in the differential diagnosis of early-stage PD from MSA-P and PSP. There is no information on the sensitivity and specificity of OSIT-J in the diagnosis of parkinsonian syndromes such as PSP and MSA-P.

Methods

We assessed the olfactory function using the OSIT-J test in 94 Japanese patients with idiopathic PD, 15 with MSA-P, 7 with PSP, and 29 age-matched control subjects.

Results

The mean ± SD score of OSIT-J in patients with PD (4.4 ± 2.9) was significantly lower than in patients with MSA-P (8.7 ± 2.2, P < 0.0001), PSP (7.6 ± 2.2, P < 0.0057), and control subjects (10.5 ± 1.3, P < 0.0001). The area under the curve (AUC) of receiver operating characteristic (ROC) to discriminate PD from normal control using OSIT-J scores was 0.97 (95% confidence interval, 0.95-1.00), from MSA-P 0.87 (0.80-0.95), and from PSP 0.81 (0.66-0.96).

Conclusion

The OSIT-J is a potentially useful clinical test not only for detection of olfactory deficit in PD but also for differentiating PD from MSA-P and PSP.