Multicenter Validation of a Telephone-Based Caregiver Interview for Longitudinal Assessment of Outcome after Severe Brain Injury: A Traumatic Brain Injury Model Systems Study

There is limited information about long-term outcomes following severe acquired brain injury (ABI). This is due, in part, to the lack of validated longitudinal assessment measures that can be administered remotely. To address this gap, we developed a caregiver-administered telephone interview designed for the remote evaluation of the functional status of patients who are too impaired to provide reliable self-report. The interview comprises items drawn from three existing standardized instruments: the Coma Recovery Scale-Revised (CRS-R), Cognitive Impairment subscale of the Confusion Assessment Protocol (CAP-Cog), and Galveston Orientation and Amnesia Test (GOAT) (subsequently referred to as the CRS-RT, CAP-CogT, and GOAT-T to reflect telephone administration). The CRS-RT items evaluate the level of consciousness, while the CAP-CogT and GOAT-T items assess basic aspects of cognition. We administered the caregiver interview to 48 caregivers of persons with severe acquired disability (i.e., vegetative state to confusional state) and validated caregiver responses by conducting in-person patient examinations using the original versions of the assessment instruments. To establish the concurrent validity of the caregiver interview, we assessed the correlation between the findings from the caregiver interview and the patient examination, using Lin's concordance correlation coefficient (CCC). The mean (standard error) sensitivity, specificity, and accuracy across both sets of interview items were 0.82 (0.03), 0.68 (0.04), and 0.75 (0.03), respectively. Lin's CCC between caregiver responses to the nine interview items addressing the level of consciousness and the corresponding patient examination findings was 0.78 (95% confidence interval [CI]: 0.65, 0.90), with six items exceeding our <i>a priori</i> cut-off of ≥0.70. However, the correlation between caregiver responses to the eight basic cognition items and the patient examination findings was poor (Lin's CCC = 0.37, 95% CI: -0.09, 0.82), with only three items at or above the cut-off. These results indicate that the CRS-RT can be administered remotely to caregivers of persons with severe ABI-related disability to monitor neurobehavioral status longitudinally. The CAP-CogT and GOAT-T items require further study before they can be used for clinical outcome assessment.