Reliability of the Brazilian Portuguese version of the Neuropsychiatric Inventory (NPI) for patients with Alzheimer's disease and their caregivers

Background: Behavioral symptoms and caregivers' responses may differ among various ethnic and cultural groups. Therefore it is important to have a reliable instrument to assess behavioral disturbances of dementia in various cultures. The Neuropsychiatric Inventory (NPI) has been widely used in many countries. To date there has been no reliability study of this instrument in Brazil. Methods: The psychometric properties of the Brazilian Portuguese version of the NPI were studied in a sample of 36 Alzheimer's disease (AD) outpatients from southern Brazil. Test-retest, inter-rater reliability and internal consistency were estimated. The profile of neuropsychiatric symptoms and caregiver distress were also evaluated. The NPI was translated into Portuguese and then back translated to English. Results: The Brazilian Portuguese version of the NPI showed good inter-rater and test-retest reliability with the coefficients of all scales > 0.85. Internal consistency was also good (Cronbach's alpha 0.70 for total severity and distress). Apathy provided higher NPI scores of total severity and distress. Conclusions: This NPI version was found to be a reliable instrument for the evaluation of neuropsychiatric symptoms and caregiver distress due to dementia in AD. The profile of behavioral disturbances was similar to that observed in other countries. Severity of dementia may have biased some caregivers' answers.