Examining Agreement in Psychotic Symptom Assessment: Insights from Parkinson's Disease Dementia Dyads.

Background: Psychosis and cognitive decline often co-occur in Parkinson's Disease (PD), which complicates assessment.

Objective: We measured agreement between patients with PD and dementia (PDD) and care partners (CPs) in their independent evaluation of PD-related psychotic symptoms.

Methods: We compared responses to a PD psychosis rating scale (SAPS-PD) in 21 dyads of patients with PDD and cognitively normal CPs. We assessed the concordance of responses using the intraclass correlation coefficient (ICC). Following the psychosis assessment, the clinician used all available information and adjudicated who provided the most reliable responses.

Results: Dyads demonstrated poor concordance in summary scores (ICC = 0.464). Six of the nine individual items had poor agreement. The clinician adjudicated the patient's response as the more reliable in 71.4% of cases.

Conclusions: Although many psychotic symptoms are internal and not observable, in the context of PDD, both patient and CP inputs are valuable, but final adjudication favors patient responses.