The reliability and validity of the Xhosa version of the EQ-5D

This study aimed to examine the reliability and validity of the Xhosa version of the EQ-5D, a Health Related Quality of Life measure which is often used as an outcome measure in clinical trials, within an urban Xhosa speaking population.

The test-retest reliability was examined on a community and institutional sample of 88 subjects, who were interviewed twice, one week apart. Forty-nine out- and in-patients participated in the second part of the study, in which the concurrent validity of the EQ-5D against existing Xhosa measures of similar domains as the EQ-5D was examined.

The Intraclass correlation (ICC) co-efficients between the first and second interviews ranged from 0.39 to 0.75 in different domains. The ICC for the Visual Analogue Scale of health state was 0.63. In the validity study, those who reported no problems with mobility demonstrated a significantly higher gait velocity. There was a significant difference between the rank ordering of scores on the four domains of self-care, usual activities pain/discomfort and anxiety/depression and the scores obtained on the 'gold standard' tests.

It is concluded that, although some domains might need to be examined further, the Xhosa EQ-5D is a valid and reliable instrument with which to determine HRQoL in an urban Xhosa speaking population. In order to ensure validity of results in multicultural research and drug trials, it is essential that more outcome measures are subjected to rigorous translation and testing of validity and reliability.