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Updated: Aug 25, 2026
Detecting Behavioral Deficits in Rats After Traumatic Brain Injury
Published on: January 30, 2018
Minimal Clinically Important Difference for the Rasch Neuropsychiatric Inventory Irritability and Aggression Scale
James F Malec1, Flora M Hammond2
1Department of Physical Medicine and Rehabilitation, Indiana University School of Medicine, Indianapolis, IN; Rehabilitation Hospital of Indiana, Indianapolis, IN; Mayo Clinic, Rochester, MN.
Objective:
To determine the minimal clinically important difference (MCID) for a Rasch measure derived from the Irritability/Lability and Agitation/Aggression subscales of the Neuropsychiatric Inventory (NPI)-the Rasch NPI Irritability and Aggression Scale for Traumatic Brain Injury (NPI-TBI-IA).
Design:
Distribution-based statistical methods were applied to retrospective data to determine candidates for the MCID. These candidates were evaluated by anchoring the NPI-TBI-IA to Global Impression of Change (GIC) ratings by participants, significant others, and a supervising physician.
Setting:
Postacute rehabilitation outpatient clinic.
Participants:
274 cases with observer ratings; 232 cases with self-ratings by participants with moderate-severe TBI at least 6 months postinjury.
Interventions:
Not applicable.
Main Outcome Measure:
NPI-TBI-IA.
Results:
For observer ratings on the NPI-TBI-IA, anchored comparisons found an improvement of 0.5 SD was associated with at least minimal general improvement on GIC by a significant majority (69%-80%); 0.5 SD improvement on participant NPI-TBI-IA self-ratings was also associated with at least minimal improvement on the GIC by a substantial majority (77%-83%). The percentage indicating significant global improvement did not increase markedly on most ratings at higher levels of improvement on the NPI-TBI-IA.
Conclusions:
A 0.5 SD improvement on the NPI-TBI-IA indicates the MCID for both observer and participant ratings on this measure.
