Background <p>Bristol Myers Squibb (BMS), in collaboration with ZS and Tufts CSDD, recently conducted a detailed evaluation of participation burden associated with clinical outcome assessments, including patient reported outcomes.</p> Methods <p>A mixed-methods approach was used including an online global survey followed by in-depth interviews with patients and investigative sites to understand underlying causes of participation burden.</p> Results <p>258 patients completed the online survey, 12 interviews were conducted among patients, and 12 interviews were conducted among investigative site personnel. The results show significant differences in patient perceptions of participation burden depending on the modalities and types of clinical outcome assessments administered in clinical trials. Specific modalities associated with elevated burden included those longer than 30&#xa0;min and those completed several times per month. Perceived burden of clinical outcome assessments varied significantly by patient age and ethnicity. Investigative sites also reported the burden associated with administering electronic clinical outcome assessments – most notably the technical challenges and additional patient assistance required during initial setup, first patient visit, and technology management across different sponsors.</p> Conclusion <p>The results of this study raise clinical team and protocol author awareness of the patient participation burden associated with distinct types and modalities of clinical outcome assessments and informs decisions to selectively reduce this burden. The results of this study build on the Tufts CSDD-ZS Patient Burden Algorithm.</p>