# Aphasia-specific or generic outcomes? a comparison of two health-related quality of life instruments for economic evaluations of aphasia treatments

## TL;DR

This study compares two quality of life questionnaires for people with aphasia, finding that the generic EQ-5D-3L may not be sensitive enough for economic evaluations of aphasia treatments.

## Contribution

The study evaluates the suitability of two HRQOL instruments for economic evaluations in aphasia, highlighting limitations of the EQ-5D-3L and suggesting the need for better alternatives.

## Key findings

- The EQ-5D-3L showed high ceiling effects and weak convergent validity with the aphasia-specific SAQOL-39g.
- Factor analysis revealed that the two instruments measure distinct aspects of health-related quality of life.
- EQ-5D-3L utility scores had reasonable discriminative ability for poor HRQOL but may lack sensitivity for mild to moderate aphasia.

## Abstract

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.

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).

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.

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.

The online version contains supplementary material available at 10.1007/s11136-025-04040-8.

Up to 40% of patients with stroke experience aphasia, a communication disorder significantly impacting health-related quality of life. Economic evaluations are critical to guide resource allocation to treatments that show the greatest health benefits to patients and value to society. We compared two questionnaires measuring health-related quality of life. One questionnaire, the EQ-5D-3L has a scoring system adapted for use in economic evaluations. The second questionnaire, the SAQOL-39g, does not have an adapted scoring system, but was designed to measure elements of quality of life relevant to people with aphasia.

Results were from a randomised control trial of 201 people with long-term aphasia. Participants were mostly men with a median age of 63.9 years. Many participants reported no problems with their health on the EQ-5D-3L before treatments, but few did so on the SAQOL-39g. We propose that the EQ-5D-3L may lack sensitivity to measure improvements following treatments in people with mild to moderate aphasia. Our analysis showed the EQ-5D-3L and SAQOL-39g measure different parts of health-related quality of life: the SAQOL-39g alone measures communication, the EQ-5D alone measures pain/discomfort, and both measure physical functioning and psychosocial well-being. These results are important for economic evaluations using the EQ-5D-3L in populations with aphasia. To ensure economic evaluations are meaningful and aphasia treatments can be reliably evaluated, there is a need evaluate alternative questionnaires that 1-have scoring systems adapted for use in economic evaluations and 2- measure communication-related elements of quality of life that are relevant to people with aphasia.

The online version contains supplementary material available at 10.1007/s11136-025-04040-8.