Reliability, validity and clinical usefulness of the BNI fatigue scale in mild traumatic brain injury.
ABSTRACT The purpose of this study was to examine the reliability, validity and clinical usefulness of the Barrow Neurological Institute Fatigue Scale (BNI-FS) in patients with mild traumatic brain injuries (MTBI).
Participants were 125 patients enrolled from the Emergency Department (ED) of Tampere University Hospital, Finland who had sustained an MTBI. The average number of days from injury to the interview and questionnaires was 24.1 (SD = 5.4, Range = 8-38). The patients were compared to a healthy control sample. Patients completed the Barrow Neurological Institute Fatigue Scale, Fatigue Impact Scale (FIS), Beck Depression Inventory-Second Edition (BDI-II), Rivermead Post-concussion Symptom Questionnaire (RPSQ) and the health assessment measure EuroQol five Dimension (EQ-5D) Visual Analogue Scale (VAS).
The MTBI group had significantly greater total scores on the BNI-FS than the control group (p < 0.005, Cohen's d = 0.40). The internal consistency reliability for the BNI-FS, as measured by Cronbach's alpha, was 0.96 for the MTBI group and 0.87 for the control group. The 10 items were submitted to an exploratory principal components factor analysis with varimax rotation in the MTBI group. A one-factor solution, accounting for 73.3% of the total variance, appropriately summarized the data. The correlation between the BNI-FS and other measures was rs = 0.68 (p < 0.001) for the BDI-II, rs = 0.68 (p < 0.001) for the RPSQ, rs = -0.39 (p < 0.001) for the EQ-5D VAS and rs = 0.84 (p < 0.001) for the FIS. Fatigue ratings correlated positively with number of days post-injury before returning to work (rs = 0.27, p < 0.006).
The BNI-FS is a relatively new, brief and highly reliable measure of fatigue.