Screening for depression in Parkinson's disease: the performance of two screening questions

Background: the study objective was to evaluate the validity of the two questions recommended by the UK. National Institute for Health and Clinical Excellence for depression screening in Parkinson's disease (PD). Methods: one hundred and twenty patients attending a PD out-patient clinic were interviewed in a standardised manner using relevant sections of the Present State Examination-Schedules for Clinical Assessment in Neuropsychiatry to identify depression according to Diagnostic and Statistical Manual (4th edition) criteria. Participants then completed the two depression screening questions and the 15-item Geriatric Depression Scale (GDS-15). Results: sensitivity, specificity, positive and negative predictive values of the two questions and GDS-15 for major and minor depression combined were calculated for different cut-off scores and a receiver operating characteristics (ROC) analysis was conducted. A threshold of one or more positive responses to the two screening questions gave a sensitivity of 100% and specificity of 84% (positive predictive value 54%, negative predictive value 100%). The area under the ROC curve was 0.95. The optimal cut-off for the GDS-15 was 5/6, which gave a sensitivity of 84% and specificity of 89% (positive predictive value 59%, negative predictive value 97%), and the area under the curve was 0.92. Conclusion: this study shows that the two depression screening questions can be used as an initial screen for depression in patients with PD who have no significant cognitive impairment. A positive response to either of the questions would indicate that further diagnostic assessment may be warranted.