Background <p>During the past five years, there has been growing interest among pharmaceutical companies in incorporating patient needs and preferences early in the protocol design process. Through individual and larger group studies, the Tufts Center for the Study of Drug Development (Tufts CSDD) has collaborated with 14 pharmaceutical companies in applying a validated approach early in the protocol design process to assess patient participation burden. Data from these assessments has been aggregated to analyze trends in participation burden between 2011 and 2022.</p> Methods <p>156 phase II and III protocols were analyzed.</p> Results <p>Overall burden for patients to participate in phase II and III clinical trials has been rising steadily since 2011. Procedures contributing most to participation burden include patient questionnaires, lab and blood work and routine procedures conducted at each planned visit. A notable increase in the average duration of each visit per protocol was observed in large part due to the volume of procedures performed per visit. A growing proportion of procedures contributing to participation burden are those supporting supplementary, tertiary and exploration endpoints. The results of this aggregate analysis demonstrate the value of assessing patient participation burden to inform protocol design optimization.</p>