Informant- and Self-Appraisals on the Psychosis and Hallucinations Questionnaire (PsycH-Q) Enhances Detection of Visual Hallucinations in Parkinson's Disease.

BACKGROUND

Clinicians vary in their ability to elicit and interpret hallucinatory symptoms in patients with Parkinson's disease (PD). There is limited evidence for informant-report measures of PD hallucinations as adjuncts to clinician-rated scales.

OBJECTIVES

To determine the utility of an informant version of the validated Psychosis and Hallucinations Questionnaire (PsycH-Q) for assessing the presence and severity of hallucinations in PD; and, to evaluate accuracy of clinician judgements by comparison with informant report and self-report.

METHODS

One hundred sixty-three PD patient-informant dyads completed self- and informant-report versions of PsycH-Q and three common questionnaire measures: Neuropsychiatric Inventory Questionnaire; Parkinson's Psychosis Questionnaire; and Scales for Outcomes in Parkinson's disease-Psychiatric Complications. We compared self-ratings and informant ratings across analogous subscales for the presence of hallucinations with clinician interview ratings on MDS-UPDRS as a diagnostic standard.

RESULTS

There was a low level of agreement between dyads (average κ = 0.39; κ range = 0.32-0.47;  < 0.001), and patients indicated the highest prevalence of hallucinations compared to informant or clinician estimates. Clinician interview missed 32% of PsycH-Q hallucinators identified by dyads. Relative to the sample, 22 patients with exclusively clinician-appraised hallucinations had poorer overall quality of life measured by the Parkinson's Disease Questionnaire.

CONCLUSIONS

The sole use of clinician-rated scales may underestimate prevalence of PD hallucinations, and there is room for introducing self- and informant-report tools. Nonetheless, clinician appraisals are critical in cases when informant and patient insight might be affected by the impact of illness on quality of life.