Utility of the Japanese version of the 9-item Wearing-off Questionnaire

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.