Measurement Equivalence of Standard and Zoom-Enabled Electronic Clinical Outcome Assessments: Implications for Patient Accessibility in Clinical Trials

Objectives Diversity and inclusion in clinical trials remains an important topic, particularly for participants with disabilities such as vision impairment. With advances in smartphone and tablet technologies and their increasing use in clinical trials, accessibility features, such as pinch to zoom, are now at our fingertips. However, implementing such accessibility features when collecting electronic clinical outcomes assessments (eCOA) does not come without risks and must be designed with careful consideration and scientifically tested to ensure no impact to data integrity. Therefore, the objectives of this study were to determine the measurement equivalence of an eCOA questionnaire with and without a zoom accessibility feature and test its usability. Methods An eCOA app with a zoom accessibility feature was designed following industry standards for eCOA best design. Participants (n = 53) with chronic or recent pain completed a questionnaire with standard response scales (verbal rating scale, numerical rating scale, and visual analog scale), with and without the zoom accessibility feature enabled, in a randomized crossover design. Intraclass correlation coefficients were determined. A subset of participants (n = 10) with vision impairment participated in a usability testing interview. Results The intraclass correlation coefficients analysis showed high agreement (0.894-0.982) between zoomed and non-zoomed completions of the verbal rating scale, numerical rating scale, and visual analog scale. Participant usability testing showed good ease of use, ability to read the screen, and usefulness of the zoom feature, especially when not wearing corrective measures for vision impairment. Conclusions These findings support the use of a specially designed eCOA zoom accessibility feature for use in clinical trials.