Objective: To develop and assess the psychometrics of a disease-specific psychosis severity rating scale (Psy-PD) for a one-stop assessment of change in psychotic symptoms in patients with Parkinson’s disease (PD).

Background: Psychosis, a common and complex neuropsychiatric non-motor symptom (NMS) of PD, is a major determinant of quality of life [1], caregiver burden [2], and nursing-home placement [2][3]. Although various scoring methods have been proposed, there is no single instrument (questionnaire or scale) that allows a comprehensive assessment of the full spectrum of the range and nature of PD psychosis.

Method: Cross-sectional Phase I data from an ongoing multi-centre prospective 2-phase study to validate the Psy-PD (Psy-PD; IRAS ID 229095) were analyzed in a sample of 34 patients with PD psychosis (comprising of minor hallucinations, major hallucinations, and delusions). Configured as a rater-based instrument, item selection and formulation were based on existing scales assessing psychosis in other conditions, pertinent literature review, and expert consensus (including patient group representatives). 10 neurologists and 25 healthy controls were also included in the cognitive pre-testing and administration of the initial version of the Psy-PD. Primary data on its feasibility, acceptability and reliability were obtained.

Results: The pilot study, carried out in English in the United Kingdom, demonstrated that the preliminary version of the Psy-PD was comprehensive, comprehensible, and applicable. Data quality was good; moderate-to-high floor effect was present in patients for most Psy-PD domains, particularly among the delusion subtypes, with several domains showing weak internal consistency. Time of administration was approximately 15 minutes.

Conclusion: Qualitative and quantitative research findings have led to a definitive version of the Psy-PD scale, which is currently being validated in both UK and Singapore (Phase II).

References: [1] Holroyd S, Currie L, Wooten GF. Prospective study of hallucinations and delusions in Parkinson’s disease. J Neurol Neurosurg Psychiatry. 2001;70(6):734-738. [2] Goetz CG, Stebbins GT. Risk factors for nursing home placement in advanced Parkinson’s disease. Neurology. 1993; 43:2227–2229. [3] Aarsland D, Larsen JP, Tandberg E, Laake K. Predictors of nursing home placement in Parkinson’s disease: a population-based, prospective study. J Am Geriatr Soc. 2000;48:938–942.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/developing-a-novel-disease-specific-psychosis-severity-scale-in-parkinsons-disease-psy-pd-a-pilot-study/