Assessing Psychometric Equivalence of Paper-and-Pencil and Interactive Voice Response (IVR) Modes of Administration for the EQ-5D and the QLQ-C30

Abstract

Electronic data capture technologies, such as interactive voice response (IVR) systems, are emerging as important alternatives for collecting self-reported data. The purpose of this research was to assess the measurement equivalence between the original paper-based versions and the adapted interactive voice response (IVR) versions of the EQ-5D and the QLQ-C30. Furthermore, we examined the test-retest reliability of two consecutive administrations of the IVR versions of the EQ-5D and the QLQ-C30. The comparison of the paper and IVR versions of the EQ-5D was conducted utilizing a crossover design with subjects randomly assigned to one of two assessment orders: 1) paper then IVR or 2) IVR then paper. A convenience sample of in-treatment outpatient cancer clinic patients (n=139) were asked to complete each assessment two days apart. For the test-retest component, outpatient cancer clinic patients (n=127) were asked to complete the IVR-based EQ-5D twice, two days apart. The analyses tested for mean differences (paired t-test) and test-retest reliability (ICC).In the crossover analysis, ten of the fifteen mean differences analyzed for the scales and items of the QLQ-C30 were within the equivalence interval set a priori. The ICCs for the scales and items of the QLQ-C30 ranged from 0.698 to 0.899. Two of the items, insomnia and appetite loss, did not meet our threshold of being statistically different from an ICC of 0.70. The EQ-5D index score means were equivalent between paper and IVR, however the EQ VAS score differences were not wholly contained in the equivalence interval. The ICCs were above 0.890 for the index and the EQ VAS. In the test-retest analysis, the ICCs for the nine multi-item scales for the QLQ-C30 were all above 0.69, ranging from 0.698 to 0.891. Ten of the fifteen mean differences analyzed were within the equivalence interval set a priori. For the EQ-5D, the mean differences were wholly contained within the equivalence intervals for both the index and the EQ VAS and the ICCs were significantly different from 0.70. Overall, the IVR version of the questionnaires provided psychometrically equivalent results to those obtained on the original paper version and showed good stability over time.