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

Authors

  • Javier Virués-Ortega PhD,

    Corresponding author
    1. Consortium for Biomedical Research in Neurodegenerative Diseases (Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas—CIBERNED), Madrid, Spain
    • Centro Nacional de Epidemiología Instituto de Salud Carlos III, C/Sinesio Delgado, 6, 28029 Madrid Spain

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  • Carmen Rodríguez-Blázquez PhD,

    1. Consortium for Biomedical Research in Neurodegenerative Diseases (Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas—CIBERNED), Madrid, Spain
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  • Federico Micheli MD,

    1. Department of Neurology, José de San Martín Clinical Hospital, Buenos Aires, Argentina
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  • Francisco Javier Carod-Artal MD, PhD,

    1. Department of Neurology, Sarah-Brasilia Hospital, Brasilia DF, Brazil
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  • Marcos Serrano-Dueñas MD,

    1. School of Medicine, Pontifical Catholic University of Ecuador, Quito, Ecuador
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  • Pablo Martínez-Martín MD

    1. Consortium for Biomedical Research in Neurodegenerative Diseases (Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas—CIBERNED), Madrid, Spain
    2. National Center for Epidemiology, Carlos III Institute of Health, Madrid, Spain
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  • Potential conflict of interest: Nothing to report.

Abstract

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, <15%). Scaling assumptions were acceptable as noted by the range of item-total correlations (0.14–0.55, only one coefficient below 0.2). Internal consistency was adequate for research use (Cronbach alpha, 0.7). Factor analysis identified two factors that accounted for 58.5% of the variance. Low correlation coefficients were found with cognitive function (SCOPA-Cog) and disease severity (CISI-PD) (rS ≤ 0.30), whereas correlation with psychosis were high (rS = 0.56). Known-groups validity analyses indicated a significant increase in mPPRS scores by Hoehn and Yahr stage (P < 0.001). The SEM value was 1.06. Overall, the results suggest that the mPPRS is a useful tool for evaluation of psychosis in PD. The results show that some psychometric properties of the mPPRS are satisfactory albeit there is room for the improvement of scale's content validity and internal consistency. © 2010 Movement Disorder Society

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