Cross-cultural evaluation of the modified Parkinson Psychosis Rating Scale across disease stages

This study assessed the psychometric attributes of the modified Parkinson Psychosis Rating Scale (mPPRS). In an attempt to improve scale's scaling assumptions and content validity, all types of hallucinations were rated and all items were scored based on intensity. The scale was cross‐culturally adapted to four Latin American countries (Argentina, Brazil, Ecuador, and Paraguay). Acceptability, internal consistency, factor structure, convergent and known‐groups validity, and precision (standard error of measurement, SEM) were explored. A total of 388 patients with PD were included in the study (age, 64.5 ± 10.7 years; 59.8% males; PD duration, 8.2 ± 4.9 years). The mPPRS was highly usable in terms of missing values generated and scores distribution (total computable scores, 99.7%, ceiling effect,