Table 5.

Item Response Theory Scoring of the Glasgow Outcome Scale-Extended Reveals Meaningful Variance at Each Glasgow Outcome Scale-Extended Score (Where Standard Scoring Provides No Useful Variance at Each Integer)

Ordinal GOSE Score	RPQ	BSI-18 GSI	QOLIBRI-OS	SWLS
3	-.35	-.42*	.63**	.49*
4	-.38**	-.45**	.40**	.19
5	-.35***	-.29***	.43***	.29***
6	-.29***	-.26***	.30***	.16*
7	-.13*	-.22***	.24***	.13*
8	-.07	-.01	.09	-.02
Combined	-.60***	-.50***	.59***	.44***

GOSE, Glasgow Outcome Scale-Extended; RPQ, Rivermead Post Concussion Symptoms Questionnaire; BSI-18 GSI, 18-item Brief Symptom Inventory Global Severity Index; QOLIBRI-OS, Quality of Life after Brain Injury Scale-Overall Scale; SWLS, Satisfaction With Life Scale; IRT, item response theory.

Correlations reflect Pearson correlations between GOSE-IRT (scaled where higher scores reflect less disability) and each self-report scale denoted by the column headings, within subgroups stratified by GOSE overall score (i.e., GOSE-Ordinal). Ordinal GOSE score of 2 is not shown because there was no variability in IRT GOSE scores.

^* p < 0.05; ^**p < 0.01; ^***p < 0.001.