Development of Composite Scores for the TBI-QOL.

OBJECTIVE

To develop a set of composite scores that can be used for interpreting quality of life (QOL) after traumatic brain injury (TBI) using 9 of the patient-reported outcomes measures from the Traumatic Brain Injury Quality of Life (TBI-QOL) measurement system.

DESIGN

Participants completed 20 item banks from the TBI-QOL as part of a larger assessment. Composite index scores were created with normalized transformation with nonlinear area conversion using scores from 9 of the banks, and are expressed in index score units, with higher composite scores indicating better functioning. For descriptive purposes, associations among composites and individual banks were evaluated using regression, along with patterns of composite scores by injury severity groups using analysis of variance.

SETTING

Three medical centers in the United States.

PARTICIPANTS

Community-dwelling adults (n=504) with a history of TBI.

INTERVENTIONS: Not applicable.

MAIN OUTCOMES MEASURE: TBI-QOL.

RESULTS

Five composite indices were generated: global QOL, physical health, emotional health, cognitive health, and social health. Lookup tables are provided herein. Composite scores were highly intercorrelated (all r>.60, P<.0001), and individual TBI-QOL banks all correlate strongly with the global QOL composite in the expected direction (all r>.50, P<.0001).

CONCLUSION

Researchers and clinicians can use the TBI-QOL global QOL, physical health, emotional health, cognitive health, and social health composite scores to aggregate results from multiple TBI-QOL banks, which is anticipated to ease interpretation and reliability. This work additionally highlights the importance of considering nonphysical symptoms as outcomes variables for TBI research, as cognitive, social, and emotional domains were some of the most strongly correlated banks with the global QOL composite.