Validity and Reliability of the European Portuguese Version of Neuropsychiatric Inventory in an Institutionalized Sample

BACKGROUND: Neuropsychiatric symptoms are very common in dementia and have been associated with patient and caregiver distress, increased risk of institutionalization and higher costs of care. In this context, the neuropsychiatric inventory (NPI) is the most widely used comprehensive tool designed to measure neuropsychiatric Symptoms in geriatric patients with dementia. The aim of this study was to present the validity and reliability of the European Portuguese version of NPI. METHODS: A cross-sectional study was carried out with a convenience sample of institutionalized patients (≥ 50 years old) in three nursing homes in Portugal. All patients were also assessed with mini-mental state examination (MMSE) (cognition), geriatric depression scale (GDS) (depression) and adults and older adults functional assessment inventory (IAFAI) (functionality). NPI was administered to a formal caregiver, usually from the clinical staff. Inter-rater and test-retest reliability were assessed in a subsample of 25 randomly selected subjects. RESULTS: The sample included 166 elderly, with a mean age of 80.9 (standard deviation: 10.2) years. Three out of the NPI behavioral items had negative correlations with MMSE: delusions (r(s) = -0.177, P = 0.024), disinhibition (r(s) = -0.174, P = 0.026) and aberrant motor activity (r(s) = -0.182, P = 0.020). The NPI subsection of depression/dysphoria correlated positively with GDS total score (r(s) = 0.166, P = 0.038). NPI showed good internal consistency (overall α = 0.766; frequency α = 0.737; severity α = 0.734). The inter-rater reliability was excellent (intraclass correlation coefficient (ICC): 1.00, 95% confidence interval (CI) 1.00 - 1.00), as well as test-retest reliability (ICC: 0.91, 95% CI 0.80 - 0.96). CONCLUSION: The results found for convergent validity, inter-rater and test-retest reliability, showed that this version appears to be a valid and reliable instrument for evaluation of neuropsychiatric symptoms in institutionalized elderly.