Minimal clinically important difference for cognitive scales in people with Parkinson's disease with cognitive impairment.

Cognitive impairment (CI) is a significant non-motor symptom of Parkinson's disease (PD), necessitating effective assessment tools to evaluate treatment efficacy. Minimal Clinically Important Difference (MCID) thresholds provide critical benchmarks for interpreting cognitive intervention outcomes. This study establishes MCID values for PD Cognitive Rating Scale (PD-CRS), Scales for Outcomes in PD-Cognition (SCOPA-COG), and Montreal Cognitive Assessment (MoCA) in PD-CI. A total of 110 patients with PD-CI were recruited; 105 (mean age 71.96 ± 2.40 years) completed the 12-week Dual-Task Training (DTT) program and were included in the final analyses. Cognitive function was assessed using PD-CRS, SCOPA-COG, and MoCA at baseline and post-intervention, with the Global Rating of Change (GRoC) questionnaire serving as an anchor. The MCID value was determined using anchor-based and distribution-based approaches. Receiver Operating Characteristic (ROC) analysis was employed to evaluate these thresholds. Significant improvements were observed across all cognitive measures post-intervention. The anchor-based MCID values were 7.70 points for PD-CRS, 3.11 points for SCOPA-COG, and 2.05 points for MoCA, respectively. Additionally, ROC curve analysis further determined that MCID cut-off points were > 3 points for the PD-CRS, > 2 points for the SCOPA-COG, and > 1 point for the MoCA. The distribution-based MCID values ranged from 1.48 to 4.10 points for PD-CRS, 1.37 to 5.95 points for SCOPA-COG, and 0.54 to 3.71 points for MoCA. This study established MCID thresholds for PD-CRS, SCOPA-COG, and MoCA in PD-CI, providing essential tools for clinicians and researchers to assess clinically meaningful changes after cognitive intervention.