Comparing multi-attribute utility instruments: CP-6D, a Cerebral palsy specific instrument, vs AQoL-4D

ABSTRACT

Background

Economic-evaluations of Cerebral palsy (CP) were based on utility estimates of health-related quality of life (HRQoL) from generic multi-attribute utility instruments (MAUIs). However, generic instruments had limited use as they could not capture some of the important aspects of living with CP. The Cerebral palsy 6 Dimension (CP-6D) is a disease specific MAUI. In this study, we compared the results of CP-6D with the Assessment of Quality of Life (AQoL-4D), a generic MAUI, and tested the criterion validity of the CP-6D in the general population.

Methods

An online survey of the Australian general population (n = 2002), who completed both the AQoL-4D and CP-6D MAUIs, was conducted. Validity was assessed from the correlations between the domains, items and instruments. ANOVA and t-tests were used to assess the instrument’s discrimination in different social demographic categories.

Result

There was a moderate correlation between the instruments (0.64). Differences in socio-demographic characteristics showed a medium effect size (p < 0.001) in both instruments and had a similar effect on utility weights in both instruments. Although the CP-6D was more sensitive to changes in income and education.

Conclusions

Our results suggest that CP-6D and AQoL-4D were measuring a similar underlying construct. Both instruments responded similarly to socio-demographic differences.

KEYWORDS:

• Utility
• validity
• CP-6D
• AQoL-4D
• health-related quality of life
• Cerebral palsy
• preference-based measure

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewers disclosure

Peer reviewers on this manuscript have no relevant financial relationships or otherwise to disclose.

Author contribution

MB, JB, PS and MD conceived the study and contributed to the design of the study; MB wrote the first draft of the manuscript. All authors read, contributed and approved all the versions of the manuscript.

Ethics approval and consent to participate

Ethics committee approval and consent were not required for this study. The data were gathered using the ethics approval given by Griffith University Human Research Ethics Committee (Reference number: 2018/930).

Additional information

Funding

This paper was not funded.