people who have been clinically diagnosed with Parkinson's disease (PD) and have received anti PD therapy would be recruited into the study. The anti -PD treatment would not be changed in the population of the participants.

We would use the tool of 'Wearing-off 9 questionnaire' to determine the prevalence of Wearing-off phenomenon in Parkinson's patients in Shanghai

The participants would receive appropriate anti-PD medical treatments according to the patients' need during the investigation.The anti -PD treatment would not be changed in the population of the participants.

every participant receives a clinical assessment of the wearing-off symptoms by a physician and completes a self rating scale of the wearing-off 9 questionnaire (WOQ-9) to obtain a prevalence of wearing-off positive individuals( wearing-off would be diagnosed by physicians during the clinical assessments)

The physician assessment served as the standard for comparison with the WOQ-9 questionnaire. Sensitivity was defined as the probability that a PD patient, classified as having wearing-off (WO) according to physician assessment, would be classified as having the WO using the WOQ-9 questionnaire. The specificity was defined as the probability that a PD patient without the WO by physician assessments would be classified as being without the WO using the WOQ-9 questionnaire