Detection of unusual study activity
RECRUITMENT
The study launched 10 April 2019 when the five national clinical audits emailed their initial distribution lists, totalling around 2000 recipients. We reached half of our target of 500 randomised participants within a fortnight. The NDA’s distribution list was far larger than that of the other four audits, and so we had initially limited the number of invitations to approximately 500 general practices. However, given a relatively low response for this audit, we extended the invitation to all 7300 practices on the NDA distribution list. This invitation was sent 25 April 2019. We then observed a sharp increase in responses, prior to and over one weekend (Fig. Pattern of recruitment to the online trialWe completed a pre-planned, secure download of voucher request data on the following Monday morning, 29 April 2019. Our study administrator identified 268 new voucher claims from three email addresses. We were subsequently able to link these email addresses to one general practice, using a combination of a telephone number that had been logged as calling our study enquiry number, and the name provided in the relevant email addresses. The caller had enquired as to whether participants could complete the study more than once.We then inspected the study data and found emerging unusual patterns compared to earlier validity checks. We consulted our independent study steering committee, as well as the study sponsor, and suspended the online trial to allow further investigation.