Comparison of the Neurobehavioral Symptom Inventory and the Rivermead Postconcussion Symptoms Questionnaire.

Objective: This study sought to determine the similarity of constructs measured by the Neurobehavioral Symptom Inventory (NSI) and Rivermead Postconcussive Symptoms Questionnaire (RPQ) and the potential for interchangeability of scores from the two scales. Setting: Three acute inpatient rehabilitation hospitals in the USA. Participants: 497 community dwelling persons with traumatic brain injury (TBI) who completed the NSI and the RPQ during the same assessment. Inclusion criteria were (a) medical documentation of TBI, (b) age 18 to 64 years, (c) capacity to give informed consent, (d) resides in the community, (e) ability to complete all study measures in English, (f) absence of interfering medical or psychiatric condition. Design: Prospective cohort observational study Main Measures: NSI; RPQ Results: Scores from the NSI and RPQ showed a strong association (Spearman's r = 0.89). Exploratory factor analysis showed that items from the two measures loaded on similar factors. A crosswalk between the two measures was created by equating scores from the scales based on percentile ranks. Conclusion: Results indicate substantial conceptual and empirical overlap between the NSI and RPQ. The percentile crosswalk developed from this dataset may allow combined analysis of post-concussive symptoms from datasets that include either the NSI or the RPQ.