The Neuropsychiatric Inventory-Diary rating scale (NPI-Diary): a method for improving stability in assessing neuropsychiatric symptoms in dementia

Background: In health-care settings, the use of the Neuropsychiatric Inventory-Nursing Home (NPI-NH) may not always be consistent with the authors’ guidelines, which affects its reliability. To avoid this bias, a diary version of the NPI (NPI-Diary) was developed. Aims: This study aimed to evaluate the psychometric properties (internal consistency and reliability) of the NPI-Diary, and examined its convergence with the NPI-NH. Methods: Two raters administered the NPI-NH and NPI-Diary to 40 participants with Alzheimer’s disease, selected randomly from a hospital’s weekly turnover. Results: The NPI-Diary exhibited adequate internal consistency (total: α = 0.581) and test-retest reliability (total: ρ = 0.711; p< 0.01). The interrater reliability values (ICC) for the NPI-NH and NPI-Diary differed significantly (Total: NPI-NH ICC = 0.506, NPI-Diary ICC = 0.879; Frequency: NPI-NH ICC = 0.51, NPI-Diary ICC = 0.798; Severity: NPI-NH ICC = 0.491, NPI-Diary ICC = 0.809). The convergent validity between the two inventories was also significant (total: ρ = 0.48; p< 0.01). Conclusions: The NPI-Diary showed more appropriate validity and reliability compared to the NPI-NH, when administered in a highly variable sample, as is generally the case in the current health-care setting.