In proportion: approaches for displaying patient-reported outcome research study results as percentages responding to treatment

Purpose: Patient-reported outcome (PRO) data from clinical trials can promote valuable patient–clinician communication and aid the decision-making process regarding treatment options. Despite these benefits, both patients and doctors face challenges in interpreting PRO scores. The purpose of this study was to identify best practices for presenting PRO results expressed as proportions of patients with changes from baseline (improved/stable/worsened) for use in patient educational materials and decision aids. Methods: We electronically surveyed adult cancer patients/survivors, oncology clinicians, and PRO researchers, and conducted one-on-one cognitive interviews with patients/survivors and clinicians. Participants saw clinical trial data comparing two treatments as proportions changed using three different formats: pie charts, bar graphs, icon arrays. Interpretation accuracy, clarity, and format preference were analyzed quantitatively and online survey comments and interviews, qualitatively. Results: The internet sample included 629 patients, 139 clinicians, and 249 researchers; 10 patients and 5 clinicians completed interviews. Bar graphs were less accurately interpreted than pie charts (OR 0.39; p <.0001) and icon arrays (OR 0.47; p <.0001). Bar graphs and icon arrays were less likely to be rated clear than pie charts (OR 0.37 and OR 0.18; both p <.0001). Qualitative data informed interpretation of these findings. Conclusions: For communicating PROs as proportions changed in patient educational materials and decision aids, these results support the use of pie charts.