The sensitivity and specificity of the 9-item Wearing-off Questionnaire

ObjectiveThis multicenter, cross-sectional study was conducted to determine the sensitivity and specificity of a 9-item Wearing-off Questionnaire (WOQ-9) compared with assessment by a clinician.MethodsPatients with a diagnosis of Parkinson's disease (PD) for ⩽5 years, and receiving stable antiparkinsonian therapy for ⩾90 days, completed the WOQ-9 before independent evaluation by the physician.ResultsOne hundred fifty-seven patients reported WO using the WOQ-9; only 79 had been previously diagnosed with WO by a physician. The most frequent items used by physicians to diagnose WO included type of symptoms (69.6%), symptom response (63.3%), and timing of symptom response (58.2%) to medication. Physician assessment of WO and WOQ-9 results corresponded in 76 of 79 cases; physicians disagreed with WO identification in 81 of 157 cases. Sensitivity of the WOQ-9 was 96.2% and specificity was 40.9%.ConclusionThe WOQ-9 is a useful screening tool to aid diagnosis of WO in PD patients.