Rasch analysis, dimensionality, and scoring of the neuropsychiatric inventory irritability and aggression subscales in individuals with traumatic brain injury

Model System:

TBI

Reference Type:

Journal article

Accession No.:

J79000

Journal:

Archives of Physical Medicine and Rehabilitation

Year, Volume, Issue, Page(s):

2018 , 99, 2, 281-288

Publication Website:

Abstract:

Study aimed to develop a more precise measure of irritability and aggression after traumatic brain injury (TBI) from the perspectives of both the individual with TBI and an observer using all behavioral item ratings for the Neuropsychiatric Inventory (NPI) Irritability and Aggression subscales. Baseline NPI data were obtained from 3 treatment studies, including 287 observer ratings and 238 self-ratings by participants with complicated mild, moderate, or severe TBI at least 6 months postinjury. Rasch and confirmatory factor analyses of the frequency and severity ratings from NPI Irritability/Lability and Agitation/Aggression subscales were conducted. Confirmatory factor analyses of both observer and participant ratings showed good fit for either a 1-factor or a 2-factor solution. Consistent with this, the Rasch model also fit the data well with aggression items indicating the more severe end of the construct and irritability items populating the milder end. The results indicate that irritability and aggression represent different levels of severity of a single construct; that is, aggression items represent greater symptom severity than do irritability items. The derived Rasch metric offers a measure of this construct based on responses to all specific items that is appropriate for parametric statistical analysis and may be useful in research and clinical assessments of individuals with TBI.

Author(s):