Implementation of an online pragmatic randomized controlled trial: a methodological case study.

Rigorous evaluation of eHealth interventions is acutely needed but can be challenging to execute in a cost- and time-efficient way. The purpose of this study is to describe a randomized controlled trial carried out as part of an approach that evaluates and informs product development throughout an intervention's life cycle. We present the methodological case of a pragmatic randomized controlled trial evaluating the effectiveness of the web-based intervention "Daily Challenge." We conducted the trial entirely online and leveraged existing resources to implement it quickly and within budget. One thousand five hundred three participants were recruited in 49 days (17.1 % of candidates assessed for eligibility). Then, 68.7 % of participants were reached for follow-up at 30 days and 62.5 % at 90 days. Data collection (baseline to 90-day follow-up) was completed within 5 months. Rigorous trials can be conducted efficiently and in a timely manner, enabling evaluation on a continuous basis. Development should include ongoing empirical input to inform product iterations.