Supplementary Material for: Diagnostics and ecological validity of the Italian version of the Parkinson’s Disease Cognitive Rating Scale (PD-CRS)

Introduction. This study aimed to assess the diagnostics and ecological validity of the Parkinson’s Disease Cognitive Rating Scale (PD-CRS) within an Italian cohort of non-demented Parkinson’s disease (PD) patients. Methods. N=128 non-demented PD patients were administered the PD-CRS, Montreal Cognitive Assessment (MoCA) and Parkinson’s Disease Cognitive Functioning Rating Scale (PD-CFRS). Receiver-operating characteristic analyses were performed to explore the diagnostics of both raw and adjusted PD-CRS scores, by operationalizing the positive state as a below-cutoff MoCA score. Correlational analyses were run to test the ecological validity of the PD-CRS against the PD-CFRS. Results. Both raw and adjusted PD-CRS scores accurately identified patients with a defective MoCA scores (AUC=.84-.85), yielding optimal diagnostics. A cutoff of <73.93, as identified on demographically adjusted PD-CRS scores, yielded the best diagnostics (sensitivity=.70; specificity=.89; positive and negative predictive values= .83 and .79; positive and negative likelihood ratios: 6.23 and .37: number needed for screening utility: .78). The PD-CRS was related to the PD-CFRS (rs=.-24; p=.018). Conclusions. The Italian PD-CRS is a diagnostically sound and ecologically valid screener for cognitive impairment in non-demented PD Patients.