Study within a trial protocol: Same-day consent vs. delayed consent in a randomized trial

Background: Randomized trials are designed to evaluate the effects of health care interventions. The recruitment process in a randomized trial can be challenging. Poor recruitment can have a negative impact on the allocated budget and estimated completion date of the study and may result in an underpowered research that will not adequately answer the original research question. Aim: We aim to perform a Study Within A Trial (SWAT) to evaluate the impact of same-day consent or delayed consent on recruitment and retention in the host trial. Methods: This SWAT is designed as an observational study. However, the host trial is a randomized controlled trial evaluating the effectiveness of an intensive lifestyle modification program in patients with peripheral arterial disease. For this trial and SWAT, same-day consent is defined as the patient giving consent on the same day, after the investigator has fully explained the predesigned information leaflet for the host trial. Delayed consent is defined as the patient feeling they still need further time to consider their decision to participate or not. Swat registration: The SWAT was registered on the Northern Ireland Network for Trials Methodology Research.