Cluster analysis of neuropsychological test results among patients with traumatic brain injury (TBI): Implications for a model of TBI-related disability

Neuropsychological test data and educational attainment for 47 patients with traumatic brain injury (TBI) were submitted to cluster analysis. Relationships of cluster membership to injury severity (coma days) and disabilities (Portland Adaptability Inventory; PAI) were examined. Cluster 1 was composed of highly educated individuals with relatively mild initial injuries, neuropsychological impairment, and disabilities. Impairments for Cluster 1 appeared more significant in contrast to probably high preinjury functioning. Cluster 2, whose members had lowest test performances on measures of remote memory and reading, may have been marginally functioning prior to injury. Those in Cluster 2 had only mild initial injuries, but showed moderately extensive disabilities on the PAI. Patients in Cluster 3 had mild initial injuries, very mild neuropsychological impairments, and mild disabilities, characterized by difficulties with planning and irritability. Individuals in Clusters 4 and 5 had more severe initial injuries, neuropsychological impairments, and disabilities. Patients in Cluster 5 showed greater perseverative tendencies and socially inappropriate behavior than those in the other clusters. Results of this cluster analysis suggest a model of TBI-related disability which predicts level of chronic disability from preinjury functioning, injury severity, and impairments in remote memory and adaptive abilities.