PURPOSE

Economic evaluations based on health-related quality of life (HRQOL) inform healthcare decisions. The generic EuroQol 5-Dimensions Health Questionnaire, 3-Level (EQ-5D-3L) permits conversion to utility values required for economic evaluations but is not validated for people with aphasia. The aphasia-specific Stroke and Aphasia Quality of Life Scale-39 g (SAQOL-39g) measures HRQOL, however, cannot be used to generate utility values. This study aimed to compare the performance of these two instruments.

METHODS

HRQOL was rated at baseline and 12 weeks in participants of the Constraint Induced or Multi-Modal Personalised Aphasia Rehabilitation (COMPARE) randomised controlled trial. We assessed: (1) distribution of self-rated HRQOL scores, (2) convergent validity between EQ-5D-3L (domains; utility values; visual analogue scale) and SAQOL-39g (domain scores; total mean scores) using Spearman's correlations, (3) Construct validity through exploratory factor analysis, and (4) discriminative ability of converted EQ-5D-3L utilities in measuring compromised HRQOL (SAQOL-39g scores ≤ 4).

RESULTS

Participants (n = 201 baseline, n = 190 12 weeks) completed both instruments (69% male, median age 63.6 years, median time since stroke 2.5 years). Ceiling effects were high for the EQ-5D-3L at baseline (45-79%) versus the SAQOL-39g (0-6%). Convergent validity between the SAQOL-39g communication domain and the EQ-5D-3L (r = 0.04-0.28) was weak at both time points. Factor analysis revealed distinct underlying constructs between instruments. EQ-5D-3L utility scores demonstrated reasonable performance (0.80 baseline; 0.78 12-weeks) in measuring poor HRQOL.

CONCLUSION

Our findings suggest that EQ-5D-3L use in economic evaluations including people with aphasia requires caution. Alternative HRQOL instruments require evaluation to ensure fair prioritisation of aphasia treatments.