BACKGROUND AND PURPOSE: The 9-item Wearing-off Questionnaire (WOQ-9) is a useful 
tool for screening of wearing-off. We performed a validation study of the 
Japanese version of the WOQ-9 (JWOQ-9) using a cross-sectional design in 
Japanese Parkinson's disease (PD) patients diagnosed with sporadic PD and 
treated with levodopa.
METHODS: Subjects with severe dementia, uncontrolled psychiatric comorbidities, 
and previous PD neurosurgery were excluded. The wearing-off phenomenon was 
detected according to the JWOQ-9, and the results were compared with independent 
evaluations of wearing-off conducted by PD specialists blinded to the JWOQ-9 
results. To validate the JWOQ-9, a sample size of at least 70 patients with 
wearing-off and 70 patients without wearing-off was required. Therefore, a total 
of 180 patients (101 patients with wearing-off and 79 patients without 
wearing-off) were enrolled.
RESULTS: The sensitivity, specificity, positive predictive value, and negative 
predictive value of the JWOQ-9 were 94.1%, 39.2%, 66.4%, and 83.8%, 
respectively. Motor symptom questions demonstrated both moderate sensitivity 
(58.1-87.3%) and specificity (60.4-87.5%). In contrast, non-motor symptom 
questions demonstrated fair to moderate sensitivity (51.5-64.6%), with high 
specificity (80.0-94.1%). Like the original WOQ-9, the JWOQ-9 exhibits 
significant value for detecting possible wearing-off.
CONCLUSIONS: The JWOQ-9 is a useful screening tool for detecting wearing-off of 
both motor and non-motor symptoms.