Statistical Analysis Plan for the SImPLE Trial: A Study to test if illustrations and plain language ImProve cLinical trial Education

Background Traditional participant information and consent forms (PICFs) have changed little over time and are often lengthy and complex. A novel consent process incorporating plain language, an infographic brochure and a short explanatory video was developed to improve communication of clinical trial information. The SImPLE study was designed to evaluate whether this novel consent process improves comprehension of clinical trial information, participant engagement and the consent experience compared with a traditional PICF. Design and Setting SImPLE is a randomised two-period crossover study involving adults receiving cancer treatment who are potentially eligible for clinical trial participation. Study materials were developed for the ANZadapt (ANZUP2101) prostate cancer clinical trial; however, participants are not being recruited to ANZadapt itself. Participants are randomised to receive either a standard 17-page NHMRC-style PICF followed by a novel consent process, or the reverse sequence, with a washout period of at least 7 days between study periods. The novel consent process comprises a simplified 4-page PICF, infographic brochure and short explanatory video. Twenty-four hours following each PICF review, participants complete a comprehension assessment and structured interview. Outcomes and Endpoints The primary endpoint is comprehension of clinical trial information, measured using a study-specific 22-item questionnaire comprising 10 true/false and 12 multiple-choice questions. Secondary endpoints include acceptability, assessed through participant preference for communication format, and engagement, assessed through confidence in explaining the trial and likelihood of agreeing to participate. Planned Analyses The primary analysis will compare comprehension scores between the novel and standard consent approaches using a paired t-test among participants completing both study periods. Secondary outcomes relating to acceptability and engagement will be summarised descriptively and compared between consent approaches as appropriate. Sensitivity analyses will be performed to assess the robustness of the primary findings and the potential impact of crossover design effects.