Table 2.

Themes, issues raised and changes made

Theme	Issues raised	Changes made to the study design or Participant Information Leaflet (PIL) to address the issues
Recruitment options: How to approach potential participants	Support for study information to be sent by GPs or to be given in consultations	Recruitment therefore comprised:
	Support for having a summary of the main points in the PIL	a. Postal invitation letter including the study PIL with a summary of the main points at the front of the PIL;
	Lack of support for receptionists or researchers handing out study information leaflets at the practice	and, where necessary or appropriate:
	Participant suggestions that attaching PIL to repeat prescriptions may be helpful	b. Invitation letter including a summary of the study PIL on collection of repeat prescription;
	Concern that those who don’t regularly go to the GP would not be reached and need for other approaches	c. Invitation during consultation with GP/Practice Nurse/Health Care Assistant at the practice;
	Importance of hearing about study through “word of mouth” and using the media to publicize study	d. Invitation to those eligible on registered research volunteer databases
		e. Posters in GP waiting rooms;
		f. Other recruitment strategies including; Media campaign involving: local and national newspapers; BBC Scotland; local radio, celebrity endorsement
		g. Publicity campaign using posters/leaflets etc. at venues such as:
		Football/Bingo halls/Bowling clubs; Smoking Cessation Clinics; Hospital main entrances/hospital clinics; Shopping Centers/Supermarkets/Pubs, etc.; Benefits offices/Post offices, etc.; Sheltered Housing /Housing Associations
		h. Community and charitable outreach programs, mobile screening clinic, pharmacist approach through practices.
Recruitment options: How to follow up non-responders	Acceptance of need to follow up non responders to give people who genuinely wanted to take part but who had forgotten to respond the opportunity to do so	Study invite reply slip gives patients the option to specify they do not want to be contacted again by research team. Non-responders are followed up by mail with one reminder. Practices will be offered the option of using the Trial Torrent software package to identify potentially eligible patients who do not respond to postal study invites so that they can be approached during routine primary care consultations.
	Dislike of telephoning or texting non-responders
	Support for non-responders being asked by GP or nurse during consultations
Practical barrier: Appointment times	Participants felt work commitments could be a barrier to participation and flexible appointment times would be needed	Those expressing interest in the study are sent the full PIL and at least 24 hours after anticipated receipt are phoned to discuss the study, answer questions, undertake a preliminary eligibility assessment and to arrange a recruitment visit at a time suitable to the patient. Patients are reminded of the appointment by phone, text message or email 48 hours prior to the appointment depending on their preferred method of contact.
Psychosocial barrier: Stigma	Participants felt stigmatized about being targeted because of where they lived.	‘These [geographical] areas have been chosen because we know that lung cancer is more common in these areas.’*
	Participants felt targeted for being smokers and wanted the researchers to acknowledge that lung cancer can also occur in non-smokers.	‘Lung cancer can happen to anyone, including the young and old and people who do not smoke, but the risk is higher in those over 50 and those who have smoked.’
	Participants were concerned that by taking part in the trial, researchers would encourage them to stop smoking.	We removed all mention of providing smoking cessation information and advice from the PIL.
Issues related to the control group	Participants did not like the use of the term usual care group to describe the control group	We changed this to non-test group, which is what participants were most comfortable with.
	Participants did not always understand why a control group was needed in the trial.	‘Whenever a new test is developed we need to find out if it works. We do this by having a group of people who have the test and a group of people who do not. Both groups need to be similar so that we can compare what happens to the people in each group.’
	Some participants said they would be put off from participating if they were assigned to the control group	‘If you are in the non-test group, the information you give us will be really important in helping us find out if the new lung cancer blood test works, by comparing what happens to both groups. By taking part, you are playing an essential role in the research and could be helping future generations.’
		‘People in the non-test group are still playing a very valuable role in the research by allowing a comparison with those whose blood is tested, and could also be helping future generations – ECLS Team’
Not understanding randomization	Participants feared that they would be chosen for some specific personal characteristic identified by someone in the trial or their doctors	‘To try and make sure both groups are the same, each person is put into a group at random. This is done by a computer putting people into one of the two groups by chance. This is the fairest way of deciding who gets the test and means everyone will have a 50/50 chance of being put in either group. This means that you are not chosen to be in a group for any particular reason.’
Understanding the nature and purpose of the test	Some participants thought the test would pick up other health problems.	‘The test is only looking for lung cancer, so will not pick up other types of cancer or other diseases.’

* Statements in quotes reflect the final wording used in PIL.