Preference-based health-related quality of life in the context of aphasia: a research synthesis

Background: Economic considerations are increasingly important in all areas of health care because of the need to determine the value of new and existing treatments. A key component of the current economic evaluation framework is the measurement of health outcomes in a manner that permits comparability across clinical areas—often referred to as “generic” outcome measurement—and incorporates societal preferences. Preference-based health-related quality of life (HRQoL) instruments are widely used to collect such data.

Aims: To provide a research synthesis regarding the consideration and/or use of preference-based HRQoL instruments in the context of aphasia. A systematic search was conducted to identify aphasia-related publications that contained any of the leading preference-based instruments; in particular, the 15D, Assessment of Quality of Life (multiple variants), EQ-5D (three-level and five-level), Health Utilities Index (Mark 2 and Mark 3), Quality of Well-Being Scale Self-Administered, and/or SF-6D (SF-36 and SF-12 versions). In addition to providing an overview of how different measures have been used in aphasia research, a focus of the evaluation was to collate evidence for measurement properties and identify knowledge gaps, providing directions for further research. A secondary objective was to explore how preference-based measures have been discussed, broadly, in the aphasia literature. The latter objective originates from a desire to reflect the extent to which aphasia researchers have considered standard approaches to outcome measurement for the purposes of economic evaluation.

Main Contribution: Eight publications (from six studies) were identified; the three-level EQ-5D was used on four occasions, and the 15D and an “accessible” version of the three-level EQ-5D were used once. The key finding is that there have been no psychometric evaluations of preference-based HRQoL instruments in the context of aphasia. One paper explicitly discussed the challenge of using standardised, generic preference-based instruments with individuals with aphasia; researchers devised an accessible version of the EQ-5D, based on pictures rather than text (this remains unvalidated and is not an official EQ-5D instrument). The absence of any supportive evidence regarding the performance of preference-based instruments in the context of aphasia hampers the ability to assess the cost-effectiveness of treatments and interventions within the current economic evaluation framework.

Conclusions: There is a distinct lack of conceptual or empirical research regarding the appropriateness of current preference-based HRQoL instruments in the context of aphasia. Development and extensive validation of an accessible, generic preference-based HRQoL instrument appears to be an appropriate research direction.