A clinical trial alert tool to recruit large patient samples and assess selection bias in general practice research

Table 1 The implementation of four recruitment steps in the CTA tool and possible benefits

Step	Definition	Example	Benefit
Identification	All possible study participants are recognized	Clinical trial alert (CTA) automated recognition running in the background of the practice computer software to filter out all women ≥60 and men ≥70	No patients are missed Net sample automatically documented No effort required for the practice staff
Eligibility check	Specifically defined inclusion and exclusion criteria are applied to the net sample	Practice staff (nurse or doctor) reviews patient data for exclusion criteria and checks appropriate box on screen	Practice staff can document exclusion criteria on the practice computer by making one click
Contact	Eligible participants are informed about the study and are asked to participate	Practice staff introduces the study and asks for patient consent Patient response is documented using practice computer	Practice staff can easily document all patient contacts using the practice computer Study centre can monitor activity
Enrolment	Patients follow through on their intention to participate in the study	Baseline osteoporosis survey is filled in using the practice computer Pseudonymised data set is immediately transferred to the study centre	No patients lost between the GP practice and study centre All survey data is immediately available