The EQ-5D-3L administered by text message compared to the paper version for hard-to-reach populations in a rural South African trauma setting: a measurement equivalence study

Introduction
Administering patient-reported outcome measures (PROMs) by text message may improve response rate in hard-to-reach populations. This study explored cultural acceptability of PROMs and compared measurement equivalence of the EQ-5D-3L administered on paper and by text message in a rural South African setting.

Materials and methods
Participants with upper or lower limb orthopaedic pathology were recruited. The EQ-5D was administered first on paper and then by text message after 24 h and 7 days. Differences in mean scores for paper and text message versions of the EQ-5D were evaluated. Test–retest reliability between text message versions was evaluated using Intraclass Correlation Coefficients (ICCs).

Results
147 participants completed a paper EQ-5D. Response rates were 67% at 24 h and 58% at 7 days. There were no differences in means between paper and text message responses for the EQ-5D Index (p = 0.95) or EQ-5D VAS (p = 0.26). There was acceptable agreement between the paper and 24-h text message EQ-5D Index (0.84; 95% Confidence Interval (CI) 0.78–0.89) and EQ-5D VAS (0.73; 95% CI 0.64–0.82) and acceptable agreement between the 24-h and 7-day text message EQ-Index (0.72; CI 0.62–0.82) and EQ-VAS (0.72; CI 0.62–0.82). Non-responder traits were increasing age, Xhosa as first language and lower educational levels.

Conclusions
Text messaging is equivalent to paper-based measurement of EQ-5D in this setting and is thus a viable tool for responders. Non-responders had similar socioeconomic characteristics and attrition rates to traditional modes of administration. The EQ-5D by text message offers potential clinical and research uses in hard-to-reach populations.