AUTHOR=Sirbu Cristian , Saxby Brian K. , McNamara Cynthia W. , Deal Linda S. 

TITLE=Longitudinal investigation of the factor structure of the Parkinson's disease activities of daily living, interference and dependence instrument

JOURNAL=Frontiers in Neurology

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2022.941788

DOI=10.3389/fneur.2022.941788

ISSN=1664-2295

ABSTRACT=The Parkinson’s Disease Activities of Daily Living, Interference, and Dependence Instrument© (PD-AID) is a patient-reported outcome (PRO) instrument, recently developed to assess the clinical benefit of Parkinson’s Disease (PD) treatment from the patient perspective. The PD-AID consists of daily administered morning and evening assessments. To benefit from the full set of the repeated observations over time, analytic approaches that account for both within-, and between-individual variability are required. The current study aimed to employ the advantages of exploratory Multilevel-Factor Analysis (MFA) on data collected from 94 participants with moderate to advanced PD, currently using and responding to L-Dopa, who completed the PD-AID twice daily as part of a  prospective, non-intervention, observational study for approximately 28 days. Average daily completion rates were comparable for the Morning and the Evening PD-AID (78% and 74%, respectively).  The intraclass correlation coefficients for the Morning and Evening PD-AID items were in the range of 0.70 to 0.90, with an average of 0.81 for the Morning PD-AID items and 0.83 for the Evening PD-AID items, suggesting that most variability (81%-83%) in responses was due to between-individual variability.  For the Morning PD-AID, one factor (including 9 out of 10 Morning PD-AID items) emerged at the between-individual level and four factors (core physical actions, basic self-care activities, feeding and interference & dependence) at the within-individual level. For the Evening PD-AID, there were four between-individual (basic ADLs, life interference, impact on planning and emotional consequences) and five within-individual factors (basic ADLs, toileting, life interference, medication planning and emotional impact).