Preliminary Validation and Responsiveness of the NMSS-OFF/ON Scale for Rapid Assessment of Non-Motor Fluctuations in Parkinson’s Disease
This study provides preliminary psychometric evidence that the 10-item clinician-rated NMSS-OFF/ON scale is a valid, internally consistent, and highly responsive instrument for assessing non-motor fluctuations in Parkinson's disease, though larger independent studies are needed to fully establish its structural validity and clinical thresholds.