We recently reported that according to patients and healthcare professionals in breast cancer and nephrology trials, teams conducting the trials got their choice of primary outcome wrong (72% of the time) more often than they got it right (28% of the time). A Patient and Public Involvement (PPI) representative, co-author of this letter, asked (on Twitter) whether PPI contributors had been involved in the design of the original trials and by extension the outcome selection. The purpose of this study was to answer this question.