The Minimal Clinically Important Difference for the Rasch Neuropsychiatric Inventory Irritability and Aggression Scale for Traumatic Brain Injury

Publication date: Available online 14 September 2017
Source:Archives of Physical Medicine and Rehabilitation
Author(s): James F. Malec, Flora M. Hammond
ObjectiveTo 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-TBI-IA).DesignDistribution-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.Main Outcome MeasureNPI-TBI-IA.SettingPostacute rehabilitation outpatient clinic.Participants274 cases with observer ratings; 232 cases with self-ratings by participants with moderate-severe TBI at least 6 months post-injury.ResultsFor observer ratings on the NPI-TBI-IA, anchored comparisons found an improvement of ½ SD was associated with at least minimal general improvement on GIC by a significant majority (69-80%); ½ 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 percent indicating significant global improvement did not increase markedly on most ratings at higher levels of improvement on the NPI-TBI-IA.ConclusionsA ½ SD improvement on the NPI-TBI-IA indicates the MCID for both observer and participant ratings on this measure.



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