Derivation of a South African tariff for the EQ-5D-5L using a personal utility function approach

This study's primary objective was to test the feasibility of using the online personal utility function (OPUF) approach and develop a preliminary utility tariff for the EQ-5D-5L based on a South African community sample.

The need for an ethnically and socioeconomically diverse sample was seen as essential. This led to the need for interviewer assistance during completion of the survey instrument and translation of the instrument into multiple languages. English, Zulu, Tswana, and Afrikaans were chosen to allow the vast majority of a community sample people to participate. A sample size of sixty respondents was based on a previous OPUF pilot valuation study for the EQ-5D-5L, and a pilot study of twenty respondents was undertaken using the English language version of OPUF.

There were sixty-one respondents in the main study with most respondent characteristics being well matched with national figures, except for language. Personal utility functions could be calculated for sixty respondents, with the mean tariff showing monotonically declining utility decrements within each dimension. An examination of individual functions showed two contrasting sets of preferences that were driven by the respondents' rating of death. A separate subgroup analysis also showed preference heterogeneity based on the home language of the respondents.

Our study showed that the application of the OPUF approach is possible in a socioeconomically diverse population in South Africa. The examination of individual personal utility functions shows marked heterogeneity of preferences that needs to be explored further so that the source of this can be established.