Background
RECRUITMENT
Online studies offer an efficient method of recruiting participants and collecting data. They are increasingly being used in health research, including for randomised trials. A PubMed search for randomised controlled trials featuring ‘online’ or ‘internet’ in the title found a total of 2742 records, with steady growth in the annual rate of such publications from the first in 1989 to 269 on 20 December 2022. Online trials can be designed so that they can filter potential participants for eligibility, consent and randomise participants, deliver interventions, collect data, and thank participants.We completed an online trial which involved all of these steps as part of a multiphase optimization strategy (MOST), a methodological approach for building, optimising, and evaluating multicomponent interventions [Our online trial corresponded to the second phase of MOST. We investigated the single and combined effects of different components of clinical audit and feedback. Audit and feedback is commonly used in healthcare quality improvement [However, the delivery of our online trial was disrupted by potentially fraudulent activity. In this paper, we describe the rationale for our original approach to recruitment, and how this inadvertently left our trial exposed to attempted fraud by one or more participants. We outline how we identified the incident and our remedial action to ensure trial integrity.