Table 4.

Feedback obtained from focus group and field notes

Face to face same-day/face-to-face prebooking
Positive	Method of recruitment open to all GP practices Easy to organise as reliant on direct patient interaction (without need for telephoning or SMS messaging) No requirement for administrative staff Face-to-face same-day: convenient for patients as no separate visit needed Face-to-face prebooking: allowed patients to be brought back at a time convenient for them
Negative	Reliant on GP engagement: CSOs having to ‘remind GPs 2–3 times per morning’ with some GPs admitting to ‘forgetting to send in patients’. Slower recruitment in smaller (less busy) practices Inefficient: CSOs present all day for a mean yield of approximately three patients.
Telephoning
Positive	Method of recruitment open to all GP practices Appointments available for up to 12 patients per half day ‘breath clinic’
Negative	Requires support of administrative staff to contact patients Administrative staff only able to give general information about study when calling patients Cost of telephoning (including staff time)
SMS messaging
Positive	More efficient than telephone booking as patients who were telephoned had already expressed interest in being involved in breath testing by responding to SMS message. This led to higher booking rates. Appointments available for up to 12 patients per half day ‘breath clinic’ Patient initial identification not reliant on attendance to GP. Potentially more convenient for patients.
Negative	Only open to GP practices with ability to send SMS messages to patients. Proportion of patients who were ultimately tested was lower than for other enrolment methods (approximately 10% uptake). Identification of patients based on database searching has the potential to be less reliable and could vary between different practices. Requires support of administrative staff to contact patients. Administrative staff only able to give general information about study when calling patients. Cost of telephoning (including staff time).
	Single practice	Hub and spoke
Positive	Patient convenience in attending own GP practice Allows for face-to-face same-day enrolment	Broader recruitment cohort Fewer CSOs required (two for single hub): reduced CSO training time and potential improved consistency and quality of sampling. More flexibility for patients wanting to book an appointment and more efficient for CSOs to collect samples.
Negative	Narrower recruitment cohort Larger no of CSOs required, with less efficient use of their time	Some patients may either not wish to or be able to travel to the central hub for testing Allocation of appointments between multiple practices, meaning that there was a requirement for a central booking system

CSO, clinical study officer; GP, general practitioner; SMS, Short Message Service.