Exploring the uptake and use of electronic cigarettes provided to smokers accessing homeless centres: a four-centre cluster feasibility trial

Inclusion criteria

• Adult smokers (aged ≥ 18 years) accessing homeless support services on a regular basis and also known to staff.

• Self-reported daily smokers only with smoking status also confirmed by support staff.

• Smoking status also biochemically verified by exhaled carbon monoxide (CO) breath test at recruitment.

To gain wider representation, we did not exclude those who reported mental illness or substance dependence.

Exclusion criteria

• Non-smokers or those reporting using another smoking cessation aid at the time of recruitment.

• Anyone aged < 18 years, reporting pregnancy or unable to consent, for example they were currently intoxicated or unable to speak English.

• All of those who were not well known to the centre staff were ineligible.

Centre 1 (electronic cigarette cluster)

This is a day centre (open Monday to Friday; 08.30–13.00) located within Northampton. Staff and volunteers, support workers, keyworkers, social workers and kitchen staff work to provide a range of facilities and programmes to serve the practical, physical and social needs of people experiencing or at risk of homelessness in the area. There is a breakfast and lunch service, training and employment skills programmes, and an emergency night shelter (run separately by the local council) for use during periods of inclement weather. The kitchen and day centre are open on Saturday mornings for people who are sleeping rough or in emergency accommodation.

Centre 2 (usual-care cluster)

This is a day centre (open Monday to Friday; 09.00–13.00) located within the city of Edinburgh. It offers breakfast, lunch and shower and clothing facilities, as well as spiritual support through chaplaincy and recreational facilities (TV, pool and day trips). Support staff provide crisis intervention advice and assistance with benefits, housing, accessing medical services for physical and mental health, and social and life skills emotional support.

Centre 3 (usual-care cluster)

This centre operates three linked sites of supported accommodation in London for people at risk of homelessness. Each site accommodates clients whose needs fall within the parameters of the level of care it is able to provide.

Site 1 has 21 bedsits in three adjoining three-and-a-half-storey houses with a shared garden and is staffed 24 hours for people with greater complex needs.

Site 2 has 12 bedsits for male residents who are semi-independent and benefit from the support of regular check-ins, health support, and help with advocacy and paperwork. The office staff are available Monday to Friday between 09.00 and 17.00.

Site 3 has seven units in one four-storey building. The residents are both men and women who are living mostly independently, with the support workers providing advocacy, signposting to services, and on-site management.

Centre 4 (electronic cigarette cluster)

Also located in London, centre 4 provides supported accommodation across four linked sites. Staff and volunteers include keyworkers, complex needs workers and kitchen and maintenance staff.

Site 1 is a 23-unit residential support service for men and women. Single accommodation units are set on two storeys and overlook an enclosed communal garden. There is a multipurpose meeting space in a small unit in the garden where staff run skills classes and social groups. Staff are on-site 24 hours for management and security. Residents have a range of abilities and needs, with the aim of returning to independent living. Staff aim to support people with complex needs through semi-independent living with keyworker support, advocacy and daily check-ins.

Site 2 is a 13-unit women-only supported accommodation, offering support to women who have been or are at risk of becoming homeless. The accommodation provides single-occupancy accommodation. There is a shared garden with chickens and a shared communal lounge and kitchen, but no private meeting spaces. Keyworkers provide support sessions within usual working hours: 09.00 to 17.00.

Site 3 is a short-stay house and site 4 provides first-night accommodation only (to provide emergency accommodation intended for people who are newly homeless or acutely at risk of rough sleeping).

The researchers routinely kept reflexive diaries to record observations and reflections about local contexts, as well as notes on the psychological impact of working in new and sometimes unpredictable environments where people are reacting to multiple, chronic and/or acute stressors and complex needs. These research notes formed the basis of debriefing meetings and discussions in the research team, in part to be informative of ecological differences between sites as well as to systematise the physical and psychological safety of the researchers.

Pre-intervention staff training

The research team provided four education and training sessions to staff in each centre, 1–2 weeks before recruitment started. The educational content followed National Centre for Smoking Cessation and Training recommendations, to ensure that centre staff had a basic knowledge of the issues that surround smoking and smoking cessation and to optimise the delivery of the EC and UC interventions. The training was developed and led by Dr Deborah J Robson (King’s College London, London) with the support of the research team (LD, AT, SC, IU and AF); Table 2 presents an overview of the delivery of the staff education and training to 32 staff members across the centres. However, not all staff were able to attend the education and training sessions. In addition, new staff were employed in some centres during the intervention delivery phase of the study.

Education and training content for both intervention arms included the following:

• prevalence and patterns of smoking among the wider population and people experiencing homelessness

• health effects of smoking

• benefit of smoking cessation

• common misperceptions around smoking cessation in the context of other addictions and mental illness

• why this study was important and why it was needed now

• how to complete the baseline and follow-up forms and what was expected from staff.

Additional electronic cigarette training

Staff were expected to deliver the intervention and were therefore provided with information on the evidence base of EC use, clinical effectiveness and safety among the wider population and a rationale behind why ECs may be useful for this group. In addition, in the training session, staff were provided with information about how to deliver correct advice about ECs to participants and given a practical hands-on demonstration relating to aspects of EC assembly, how to use the device, charge it, refill the tank and replace coils, and battery safety. Including the practical hands-on demonstration meant that the EC intervention training took up to 45 minutes longer than the UC training.

The research team in the EC arm provided additional coaching in preparation for each staff member’s first two keyworker sessions at baseline, and through shadowing and feedback at ongoing sessions. Ongoing informal training was provided, in the form of question-and-answer discussions with staff between keyworker sessions and before and after participants’ arrival.

Additional usual-care training

As in the EC arm, staff were asked to deliver the UC referral information and were therefore provided with detailed information on the role of SSSs, current licensed medications available to smokers in their local SSS and evidence for their clinical effectiveness. Staff were informed that, at the time of training, licensed stop smoking medicines alongside behavioural support offered at the SSS were the most effective way of quitting smoking. Details of the centre’s local SSS and how to make a referral were also included in the training.

Electronic cigarette intervention

All participants in the EC cluster (centres 1 and 4) received the same intervention.

Participants were provided with an unboxed Aspire PockeX kit (Aspire eCig UK, Peterborough, UK) starter kit comprising a tank-style refillable EC with a spare atomiser, charger and wall adapter plug. They were offered five 10-ml bottles of e-liquid, choosing from a combination of (1) e-liquid nicotine strengths (two options: 12 or 18 mg/ml) and (2) flavours (three options: tobacco, fruit or menthol). E-liquid nicotine strengths of 12 and 18 mg/ml were chosen based on previous reports from our group and others of high nicotine dependency among smokers experiencing homelessness. 14 The EC brand and e-liquid were decided on following our PPI work and advice from vapers. Vapers known to the research team who have engaged in other research suggested four of the top-selling, easy-to-use ECs. On purchasing these, smokers from one London homeless centre tried the four different ECs and provided feedback on ease of use, nicotine hit and likeability. The Aspire PockeX was consistently rated as the easiest and most satisfying to use. The flavours were recommended by a vape retailer because they are the most popular, that is best-selling, varieties.

At this time, the keyworker showed the participant how to use the device; this included how to (re)fill the liquid in the tank, how to charge the device, how to inhale and what to expect when first using the device. Participants were also provided with the device instructions, which in response to our PPI feedback had been retyped into a larger font, and a help sheet of ‘tricks and tips’ from experienced vapers. Participants were given time to try the device and experiment with the different flavours and nicotine strengths, and were permitted to switch between flavours. (Appendix 2 presents the selection of e-liquid flavours and concentrations that were given out by keyworkers.) The keyworker recorded the participants’ choices of e-liquid and the timing of the keyworker session in case report forms (CRFs) that were kept with the study equipment.

Once per week in the 3 weeks that followed the baseline meeting, participants met centre staff to report any concerns and collect up to five 10-ml bottles of e-liquid and a new atomiser. Ideally, participants met the staff member whom they had met at the baseline session and who had attended the staff training; however, because of staff turnover and time demands this was not always feasible. Staff recorded data on e-liquid and troubleshooting in the CRFs. With a larger number of participants attending follow-up appointments at centre 1, staff adopted a drop-in ‘surgery’ in which waiting participants also received peer advice and support.

Usual care intervention

All participants in the UC cluster (centres 2 and 3) received the same assessment measures, but UC differed across the two centres in this cluster.

At the end of the baseline assessment, and during the same session, participants were informed of their centre allocation. Participants were then referred to their keyworkers/other centre staff who advised them to consider quitting and provided them with the fact sheet and an adapted NHS Choices ‘help-to-quit’ leaflet; this included information about the location and opening hours of SSSs local to the centre. Paper copies of the help-to-quit leaflet (with SSSs’ contact details) were available as posters/flyers at homeless centres in the UC condition/cluster. Centre staff were asked to follow up with participants once per week for 4 weeks to record whether or not they had made contact with the SSS and to remind them to do so.

Process evaluation

All participants were asked after baseline CRF completion if they would be interested in taking part in the qualitative process evaluation. Individual interviews were conducted in a quiet, private space on homeless centre premises, between weeks 4 and 8 of the trial. A semistructured topic guide was used to ensure that all relevant topics were covered, and interviews were digitally recorded with participants’ consent.

The participants’ guide covered smoking history; awareness of local SSSs; experiences of trial processes; expectations and experiences of vaping (EC arm); and experiences of signposting to SSSs (UC arm).

The staff topic guide covered staff role and trial involvement; existing cessation support for clients; and views and experiences of the trial, processes, and the EC or UC interventions. Both guides covered unintended consequences and recommendations for improvements.

Incentives for retention

The wider literature on smoking and homelessness has shown that it is common practice to offer a financial incentive to participants and that this improves retention. 4 Regardless of cluster, all participants were compensated with a £15 high-street gift card (Love2Shop, Birkenhead, UK) for completing assessments at baseline and follow-up and the qualitative interview (totalling £75). Staff did not receive a gift card for taking part in the interviews. Participant payment was not contingent on quitting or cutting down and this was stressed to the individuals taking part.

Baseline measures (across clusters)

• Demographic information and homeless status/history.

• Cigarettes smoked per day, smoking history (e.g. length of smoking, previous number of quit attempts, support used) and past and current EC use.

• Severity of tobacco dependence, measured by the Fagerström Test of Cigarette Dependence (FTCD) (Fagerström18) and expired CO.

• Motivation to stop smoking (MTSS), measured by the Motivation to Stop Scale, a seven-level single-item instrument that incorporates intention, desire and belief in quitting smoking. 19

• Mental health status, measured using the Patient Health Questionnaire-9 items (PHQ-9)20,21 for depression (total score ranging from 0 to 27, with a higher score indicating greater severity of depression) and Generalised Anxiety Disorder-7 (GAD-7) questionnaire (total score ranging from 0 to 21, with a higher score indicating greater severity of anxiety). 22

• Alcohol use, measured using the Alcohol Use Disorders Identification Test (AUDIT), a 10-item screening instrument developed by the World Health Organization to screen for alcohol problems. Scores range from 0 to 40, with a score of > 8 indicating harmful or hazardous drinking and > 13 (females) or > 15 (males) indicating alcohol dependence. 23

• Drug use measured using the Severity of Dependence Scale (SDS), a five-item screening measure of psychological aspects of dependence yielding a total possible score ranging from 0 (no/low dependence) to 15 (high dependence). 24

• General health-care and service use measured using an adapted health-care and social service utilisation questionnaire relating to services accessed in the last 4 weeks.

• Health-related quality of life (HRQoL) measured using the EuroQol-5 Dimensions, three-level version (EQ-5D-3L), a widely used measure that provides a single value for health status that can be used in the clinical and economic evaluation of an intervention. 25,26

All questionnaires and measures have good psychometric properties and have been used in previous research with vulnerable populations.

Follow-up data collection

Feasibility study outcome measures

• To assess willingness to take part in the study, we recorded (1) the number of people who were asked, (2) the number eligible to take part and (3) the number who consented to take part.

• Retention and engagement were measured by recording (1) the proportion of participants who completed assessment measures in each arm at each time point, and (2) the proportion of participants still using ECs in the intervention arm and who had visited the SSS in the UC arm.

• To estimate the parameters for future trial at each follow-up point, we recorded (1) CO-validated sustained abstinence (from 2 weeks post quit date allowing up to five slips); (2) CO-validated 7-day point prevalence abstinence (i.e. no smoking at all in the past 7 days); and (3) the proportion achieving 50% smoking reduction [calculated by subtracting cigarettes per day (CPD) at follow-up from baseline].

• To explore the feasibility of collecting data on contacts with health-care services, we recorded participant utilisation of primary and secondary health-care services using a self-report questionnaire.

• Data on staff contact time, non-contact time and other resources used in EC and UC delivery, including staff costs, ECs and other costs incurred, were collected to provide an indicative cost of the intervention.

The research team collected all of the baseline and consent data and the 4-, 12- and 24-week follow-up data.

Contamination

Contamination in the context of this design was defined as a participant receiving the intervention delivered by another participating centre, for example a participant in UC receiving a free EC starter pack from one of the EC clusters.

Sampling and recruitment for the qualitative process evaluation

All those enrolled in the trial were asked at baseline about their willingness to take part in the process evaluation interviews and whether or not they were willing to be contacted at a later date to arrange an interview. After the intervention phase, those who had consented to be contacted were approached by a researcher by telephone, or in person at the homeless centre, and invited to take part. At centre 1, staff identified participants whom they felt would be most willing to take part. Throughout the centres, staff who were supporting the participants and the project were also eligible to take part in an interview. Potential interviewees were provided with a participant information sheet and re-contacted several days later. An interview date and time were arranged for interested participants. Written consent was obtained at the start of the interview.

Purposive sampling was utilised with a pre-determined target to recruit approximately six trial participants and three staff members at each of the four homeless centres. Trial participants were also to be sampled according to (1) smoking status at week 4 of the trial and (2) whether or not they completed the week 4 follow-up.

Process evaluation

Interviews were conducted between February and July 2019 by one of a mixed-sex team of three full-time qualitative researchers experienced in interviewing vulnerable groups (AF, AT and IU).

Outcome: record the number of smokers asked to take part and the number of smokers who consent

Across the four centres, 177 participants were initially invited to take part. Of these, 24 were not eligible (16 in the EC arm and eight in the UC arm). Of the remaining 153 eligible individuals (90 in the EC arm and 63 in the UC arm), 80 consented to take part in the study: 48 (56%) in the EC arm and 32 (50.5%) in the UC arm. Although we did not reach the recruitment goal of 120 that we set ourselves (based on our preliminary scoping work), we did recruit these 80 participants during the originally specified 5-month period. Recruitment also differed between centres; the two day centres were most successful in terms of recruitment (39 consented at centre 1 and 22 at centre 2), together accounting for 77.5% of the total sample, and there was a waiting list of participants who could not be recruited at centre 1 as the researcher had to move on to the next centre. The residential units had fewer eligible individuals, including fewer smokers, and potential participants were less available because of work or other appointments and less interested in the study. Furthermore, there was less opportunity to recruit in the residential centres because of centre space and room availability, and issues around disturbing residents (see Discussion for more information).

Outcome: record (1) how many participants complete assessment measures in each arm at each time point, and (2) how many participants are still using electronic cigarettes in the intervention arm

The CONSORT flow diagram presents the participant numbers at recruitment, and follow-up data by intervention (Appendix 1). In the EC cluster, retention rates were 81%, 69% and 73% at 4, 12 and 24 weeks, respectively. In the UC cluster, retention rates were 66%, 53% and 38% at 4, 12 and 24 weeks, respectively.

There was a lower rate of attendance in the UC intervention at the 12- and 24-week follow-ups. The most common reason for not following up was that participants were no longer attending the services; although exact reasons were not formally documented by the research team, these reasons were highlighted informally by conversations with centre staff.

This difference in retention between arms did not appear to be due to the UC condition per se but, rather, due to baseline differences that might influence the ability to attend follow-ups. The UC arm was associated with a higher incidence of criminal background, illness, disability, substance abuse, anxiety and lower motivation to quit (see Table 3). This was particularly the case for centre 2 (day centre in Edinburgh; see Differences between the intervention arms), which was also associated with a far lower 24-week retention rate (26%) than centre 3 (residential centre in London; 67%).

We asked all participants in the EC intervention if they were still in possession of the EC that we had provided (although they did not have to present it at the appointment), and whether or not they were still using the EC. Assuming that all those who did not attend follow-up sessions did not still have, or were not still using, the EC, at 24 weeks 46% (22/48) still had the EC that we had provided and 56% (27/48) were still using it. Table 4 presents the data based on the number of participants who attended and answered the question at each follow-up. The greatest fall in use was between the 12-week and the 24-week follow-ups; however, 63% of those asked self-reported that they were still in possession of the device. Similarly, in relation to still using an EC, the greatest fall was between the 12-week and the 24-week follow-ups; however, of those in attendance at 24 weeks, 79% reported that they were still using an EC, either the device that was provided at baseline or a different one.

Outcome: qualitative interviews with 4-week completers and non-completers, quitters and smokers (N = 24, approximately six per site) between weeks 4 and 8 across both arms

This section presents the findings of 22 in-depth qualitative interviews with a subsample of study participants. Given the difficulty in contacting most of those participants who had not completed their 4-week follow-up, and with the majority of study participants smoking at week 4, it was not possible to conduct interviews with a good range of completers and non-completers, quitters and smokers as intended. However, there is a good spread of qualitative participants across the four homeless centres and both study arms (see Appendix 3 for the qualitative sample characteristics). Nineteen interviewees (86.4%) had completed their 4-week follow-up and three (13.6%) had not completed this follow-up. At the 4-week follow-up, 18 of the 22 interview participants (81.8%) were smoking, one was abstinent and three did not provide smoking information.

We explored participants’ experiences of the study in line with research objective 3. The findings present six topic summary themes: barriers to and facilitators of the study and intervention engagement; experiences of the EC intervention; experiences of UC; perceptions of study processes; unintended consequences; and perceived value. Local differences, if they exist, are highlighted in the text. The section ends with a summary of key learning points for a future trial.

Outcome measure: qualitative interviews with keyworkers and front-line staff (n = 12, approximately three per site) across both arms

This section presents the findings of 12 in-depth qualitative interviews with keyworker and support staff involved in facilitating and supporting the study. This included assisting with recruitment and appointments, setting EC arm participants up with the device, for example showing them how to use the device and helping them choose an e-liquid, providing EC arm participants with weekly EC support and further e-liquid, and providing UC arm participants with brief advice on quitting and information about and signposting to the local SSS. The sample is spread across the four centres (see Appendix 3). We explored their experiences of the study in line with research objective 4. The findings present five key issues: staff assumptions; staff training; communicating the study; staff capacity to support the study; and perceived value of the study. The section ends with a summary of key learning points for a future trial.

Outcome measure: measure breath carbon monoxide levels, self-reported quit rates/cigarette consumption at each follow-up time point

Table 5 presents the cessation and smoking reduction outcomes. The CO-validated sustained abstinence rate at 24 weeks was 3 out of 35 (8.57%) for the EC arm and 0 out of 12 (0%) for the UC arm. Assuming that all those with missing follow-up data were smoking, the 24-week sustained abstinence rate was 6.25% (3/48) in the EC arm and 0% (0/32) in the UC arm.

Seven-day point prevalence rates at 24 weeks were the same as sustained abstinence rates.

Of those who returned for 24-week follow-up (not ITT), the percentage of participants who reported > 50% reduction in CPD from baseline was 43% in the EC arm and 25% in the UC arm. The percentage of those participants with > 50% reduction in expired CO was a little lower and similar between arms (EC = 20%; UC = 25%).

Outcome measure: record participant scoring on EQ-5D-3L and utilisation of primary and secondary health-care services using a self-report service-use questionnaire at each time point

The missing information on EQ-5D-3L was mostly due to absence at follow-up visits. Most of those who attended completed the measure. At baseline, 46 out of 48 participants in the EC arm and 31 out of 32 participants in the UC arm completed EQ-5D-3L. At 4 weeks, all participants in both arms who were followed up completed it. At 12 weeks, 33 out of 34 attending participants in the EC arm and all 18 attending participants in the UC arm completed it. At 24 weeks, 34 out of 35 attending participants in the EC arm and all 12 in the UC arm completed EQ-5D-3L.

Among the observed cases, no one in either arm reported severe problems with mobility at any time point. The domain with the highest percentage of severe problems was anxiety/depression at baseline, 4 weeks and 12 weeks in both arms, followed by pain/discomfort. At 24 weeks, the percentage was similar in the two domains in each arm. The proportion of participants who reported no problem was consistently higher in the EC arm than in the UC arm across all domains and all time points. This led to a consistently higher mean utility score in the EC arm among those who completed the measure (Table 6). Among those participants who completed EQ-5D-3L at all time points, the mean QALY gain was 0.195 (SD 0.097) in the UC arm (n = 11) and 0.315 (SD 0.120) in the EC arm (n = 26), over 24 weeks.

There were three sections concerning services use: SSS use at follow-ups, smoking cessation help from primary/community health-care professionals, and general health-care services. Overall, most of those participants who attended the follow-up visits completed these sections, with only individual participants having an item missing in a few questions.

Attendance at SSS sessions was very low in the UC arm. At 4 weeks, four participants out of 21 contacted a SSS. One attended two sessions, three attended one and one did not answer. At 12 weeks, two participants out of 18 contacted a SSS; one attended one session and the other attended two. At 24 weeks, 2 out of 12 participants contacted a SSS; one attended one session and the other attended two. Using the resource impact template for smoking cessation service,34 the unit cost per session was estimated at £12.82. In the UC arm, the mean cost of SSS sessions was £3.21 (SD £9.18) at 4 weeks (n = 20), £2.14 (SD £6.60) at 12 weeks (n = 18) and £3.21 (SD £7.97) at 24 weeks (n = 12). In the EC arm, there was no SSS session cost incurred as none of the participants reported attending any session.

At 4 weeks, 3 out of 21 participants in the UC arm used other medications supplied by a SSS, including inhaler, patches and lozenges, with a mean cost of £5.68 (SD £14.30). At 12 weeks, 2 out of 18 used patches and lozenges in the UC arm, with a mean cost of £5.43 (SD £16.01). At 24 weeks, 1 out of 12 in the UC arm used gums and patches, with a mean cost of £3.38 (SD £11.71). None of the attending participants in the EC arm reported using cessation aids supplied by a SSS. The majority of them reported using their EC device only. Among those in the EC arm who claimed that they were not using any aids supplied by a SSS or the research team, two reported using another EC device.

No one reported using varenicline or bupropion. No one purchased any NRT product. The purchase of an EC device or e-liquid was reported by a small group of participants in both arms (Table 7). Although the number of participants who reported purchasing an EC device or e-liquid remained low in the UC arm at all times, spending was higher than that in the EC arm. In the EC arm, an increasing number of participants reported purchasing an EC device/e-liquid, after the initial 4 weeks of the study.

There were very few participants receiving smoking cessation help from primary/community care professionals (GP, practice nurse, pharmacist, NHS helpline), and those who did did not access them frequently. Owing to the rare and low frequency of use, the costs of smoking cessation help from primary health-care professionals were low and, in some cases, null. Especially for the UC arm, from 12 weeks onwards, no one reported any use. The mean costs in the UC arm were £1.45 (SD £6.75) among 31 participants at baseline, and £5.81 (SD £11.83) among 21 participants at 4 weeks. In the EC arm, the mean costs were £3.66 (SD £14.41) among 47 participants at baseline, null cost among 39 participants at 4 weeks, £1.56 (SD £9.09) among 34 participants at 12 weeks, and £2.11 (SD £12.51) among 35 participants at 24 weeks. Overall, the majority of the costs were contributed to by GP advice on smoking cessation.

Very few participants reported getting NRT products, mostly on prescription or from a SSS. The participants who had got NRT products all came from the UC arm, with only one exception: two participants in the EC arm at 24 weeks also received NRT. In the UC arm, only one or two participants at each follow-up point reported getting NRT on prescription or from a SSS. At 12 weeks, one of those reported four packs of patches and four packs of lozenges in total, but five packs of each were on prescription or from a SSS, causing a discrepancy in quantity. The only participant who received NRT that was not on prescription or from a SSS was in the EC arm at 24 weeks. Overall, the costs of NRT on prescription or from a SSS were £1.72 (SD £9.59) at baseline (n = 31), £4.13 (SD £18.73) at 4 weeks (n = 21), £16.30 (SD £51.81) at 12 weeks (n = 18) and £11.46 (SD £39.69) at 24 weeks, in the UC arm. In the EC arm, no costs of NRT on prescription or from a SSS were incurred until 24 weeks (n = 35), when it was £0.89 (SD £5.26).

Among the general health-care and social services asked, some services were used by none or close to none. Among all participants who answered in this section, no one received any visit from a GP at any point in the study. In the UC arm, only one participant received one visit from a practice nurse. In the EC arm, at both 4 weeks and 12 weeks, one participant received one visit from a practice nurse, whereas at 24 weeks one participant received two. These were probably due to the homeless situation of the participants. No participant accessed a maternity service during the study period. Sex health clinic was not visited at all at baseline (i.e. the 4 weeks prior to the baseline appointment) or at 12 weeks. At 4 weeks, one participant in the UC arm reported having visited a sex health clinic twice, whereas two participants in the EC arm had done so, one once and one four times. At 24 weeks, one participant in each arm reported having visited a sex health clinic once. Except for one participant in the EC arm at 12 weeks and one in the UC arm at 24 weeks, no participants had visited an early intervention team. Both participants visited the team only once. No participant in the UC arm stayed in a detox or rehab unit. One participant in the EC arm reported both at baseline and at 4 weeks having stayed in a detox or rehab unit, and another participant reported having done so twice at the 12-week follow-up.

There was a low but constant use of emergency and hospital services in both arms. Although the majority of the responding participants did not report any use, a small group of participants visited accident and emergency (A&E) frequently or had hospital admissions (see Appendix 6). In the UC arm, 4–7 participants reported having visited A&E at different time points. The number of visits per participant ranged from one to nine. In the EC arm, 5–7 participants reported having visited A&E at different time points. The number of visits per participant ranged from one to six. Owing to the design of the questions, we were unable to tell the number of visits that led to admission. However, in the UC arm, at least five participants at baseline, two at 4 weeks, one at 12 weeks and one at 24 weeks were admitted following the A&E visit. In the EC arm, at least two participants at baseline, three at 4 weeks and one at 12 weeks were admitted following the A&E visit. The highest number of hospital outpatient appointments reported at baseline, for over the 4 weeks before baseline, was 10 in the EC arm. The longest hospital stay was 14 days, reported in the UC arm at baseline and 4 weeks, and in the EC arm at 24 weeks.

Most of the participants in both arms received prescriptions. Other more frequently used services included GP, practice nurse and adult mental health team. Overall, 10 participants in the UC arm and 14 in the EC arm accessed a drug and alcohol service at baseline. This number dropped to almost none afterwards in the UC arm, whereas it remained more or less stable in the EC arm. Similarly, a housing team was visited by nine participants in the UC arm and 12 in the EC arm at baseline. The number of participants in the UC arm who used this service then dropped to one at 4, 12 and 24 weeks, whereas in the EC arm service use ranged from 7 to 10 participants at different time points (see Appendix 7).

Owing to the ambiguous phrasing of the question regarding detox/rehab unit, the meaning of ‘visit’ was unclear, namely whether or not it indicates a period of stay. Consequently, two possible unit costs to quantify the number of use were identified: by day or by week. We could not estimate the unit cost of a simple visit to the facility. Despite this, the overall mean costs of the health-care service did not differ much because the use of a detox/rehab unit was very rare. We therefore reported the higher one of the two (by week) to present a conservative number.

The mean costs among observed cases were consistently higher in the UC arm than in the EC arm (Table 8). The large difference between arms at baseline and 4 weeks was mostly due to the much longer hospital stay in the UC arm. At 12 weeks, although the mean cost of hospital stay was still higher in the UC arm, the mean cost of drug/alcohol service and early intervention team in the EC arm offset part of the difference. At 24 weeks, the mean cost of hospital stay and drug/alcohol service in the EC arm was much higher, whereas the mean cost of A&E, early intervention team and adult mental health team in the UC arm was much higher. However, this comparison has to be taken with caution, as around 30–60% of the participants in the UC arm were lost to follow-up during the study.

Outcome measure: record all resources used in the delivery including staff costs, electronic cigarettes and other costs incurred. Staff will complete a pro forma to record contact time, non-contact time and other resources used in delivery

The training for the centre staff to deliver standard support in the UC arm and EC guidance in the EC arm was provided by the research team. For the convenience of costing, we divided the training into three components: core component, auxiliary component and extra component.

The core component of the training was the group training programme, which was delivered by the centre: two for the UC arm and two for the EC arm. For the UC arm, it was a 1.15-hour programme delivered by four trainers to one centre (seven staff) and three to the other (five staff). The help-to-quit leaflet used was printed in-house at a cost of £0.20 per leaflet. For the EC arm, the training was slightly longer, taking 3 hours (including individual coaching). Each member of staff who attended the training was provided with an EC device instruction pamphlet and an EC helpful tips pamphlet, which were both printed in-house at a cost of £0.20 per pamphlet. The training was similarly delivered by four trainers to one centre (12 staff) and three to the other (eight staff). The demonstration models of the EC were shown to the staff at the ratio of one unit per two trainees during the training, and six bottles of e-liquid (three flavours with two strengths each) were also shown. The EC starter kit was costed at £20 per kit and the e-liquid was £3 per bottle. One of the research team members who delivered the training was grade 9, three were grade 7 and three were grade 6. Their hourly costs, including superannuation and national insurance, were calculated based on the financial records of the project. The staff who received the training held various roles, resulting in varied pay grades. We used the costs information collected from centre 1 as an estimate for all those involved. The time cost of staff was £13.38 per hour, including superannuation and national insurance. The cost of staff time in delivering the EC training was £1040.93 in total and the cost in delivering the UC training was £246.65 in total. Overall, 20 staff attended EC training and 12 attended UC training. Their staff time costs were therefore £802.80 in the EC arm and £184.64 in the UC arm. The demonstration EC kit and e-liquid were reused for each training. The maximum number of staff for one training was 12. Therefore, the number of demonstration models was estimated to be six. Combining this with six bottles of e-liquid, the total costs of the EC and e-liquid were £138.00. The two pamphlets were printed for all 20 staff attending the EC training, costing £8.00 in total. The pamphlets for the UC training were printed for 12 staff, costing £2.40 in total. The costs of core component of the training were £433.70 in the UC arm and £1989.73 in the EC arm.

The auxiliary component of the training included travel, accommodation and meals for those delivering and receiving the training. These costs would vary depending on the arrangement of the training programme. In this study, we included the costs of these items if they were claimed in expenses. For travelling, only train journeys were included. Travelling within a city was not taken into account. For the train journeys, the journey duration was estimated using the National Rail website. 35 It was then multiplied by the hourly costs of the personnel who took that journey. Centres 3 and 4 were located in the same city as most of the research team and, therefore, they did not require train travel; as a result, the travelling expense and time were not costed. The return train journey to centre 1 cost £29.30 in terms of ticket and 2 hours in terms of time. To centre 2, the return journey cost £118 (one-way £59) in terms of ticket and 9 hours in terms of time (4.5 hours one-way). Three team members took a return journey to centre 1, costing £205.83 in terms of travelling time and £87.90 in terms of train tickets. Two team members went to centre 2 and stayed in a hotel. Owing to personal arrangements, only one return ticket to centre 2 was claimed and the other was a one-way ticket. This led to £425.97 in terms of travelling time and £177.00 in terms of train tickets. Their stay cost £500 for accommodation and £40 for meals. The costs of the auxiliary component of the training were £293.73 in the EC arm and £1142.97 in the UC arm.

The extra component of the training was ECs given to staff who were smokers so that they themselves could become familiar with the device. This was not applicable to all staff trained; only four EC devices were given to the staff in one centre and two to the staff in the other centre during EC training. In total, six EC devices cost £120.

In total, the cost of the training for the UC arm was £1576.66 and the cost of the training for the EC arm was £2403.46. Allocating the costs evenly to participants in each arm, they amounted to £49.27 per participant in the UC arm and £50.07 per participant in the EC arm (Table 9).

The delivery of intervention in both arms was recorded in the keyworkers’ form at baseline (visit 0), 1 week post baseline (visit 1), 2 weeks post baseline (visit 2) and 3 weeks post baseline (visit 3). Contact time was costed by multiplying the staff hourly cost by the duration of the contact. The printing cost of the help-to-quit pamphlets for the UC arm and the EC device instruction pamphlets and the EC helpful tips pamphlets for the EC arm was recorded by the research team at £0.20 per pamphlet.

Owing to staff capacity, the data on delivery sessions were not collected in the UC arm. We therefore did not know the attendance of weekly sessions (visit 0–3) and if the pamphlet was given to the participants.

For the EC arm, one participant did not attend any session and did not receive the EC starter kit or e-liquid. The remaining 47 participants attended visit 0 and received an EC starter kit and five bottles of e-liquid. Excluding one participant with a missing response, 46 participants also received the EC ‘tips and tricks’ help sheet. The mean duration of session 0 (baseline) with homeless centre staff/keyworkers was 25 minutes (SD 16 minutes, range 7–80 minutes). Overall, 30 participants attended visit 1, of whom 29 received five bottles of e-liquid and one received two bottles. Except for a missing answer for one participant, the mean session duration of visit 1 was 8 minutes (SD 4 minutes, range 1–20 minutes). Among the 22 participants who attended visit 2, 20 received five bottles of e-liquid, one received four and one received 10. Except for a missing answer for one participant, the mean session duration of visit 2 was 6 minutes (SD 3 minutes, range 1–15 minutes). The number of participants who attended visit 3 was also 22, all of whom received five bottles of e-liquid. Duration was not recorded for two participants. Among the remaining 20 participants, the mean session duration was 5 minutes (SD 2 minutes, range 2–10 minutes).

The mean cost of the EC starter kit and e-liquid was £57.46 (SD £19.91) among the 48 participants in the EC arm. The mean cost of the pamphlet was £0.39 (SD £0.06) among 47 participants in the arm. The mean cost of the sessions was £7.51 (SD £4.60) among 43 participants. The cost of intervention delivery was therefore estimated for 43 participants whose data were complete in this part; the cost was £64.35 (SD £22.89) per participant. In total, the mean cost of the EC intervention, including training and delivery, was £114.42 (SD £22.89) among 43 participants in the EC arm (Table 10).

Objective 1: recruitment – assess willingness of smokers to participate

The residential units had fewer eligible individuals, and potential participants were less available and less interested in taking part in research.

Objective 2: assess retention and engagement in the electronic cigarette and usual-care arms

Retention rates were moderate to good and were comparable to those seen in other studies on deprived groups; however, one site’s poor retention rates negatively skewed retention rates.

Objective 3: examine the perceived value of the intervention, facilitators of and barriers to engagement, and influence of local context

Perceived value of the intervention was high. Barriers were participants’ personal and psychological difficulties, especially in relation to answering the questionnaires, a sense of nervousness around research, cannabis use and staff assumptions about smoking. Facilitators were participants’ desire to change, lack of existing cessation support, a free EC and social dynamics.

Objective 4: assess service providers’ capacity to support the study and the type of information and training required

Overall, in the EC arm, staff were well equipped to support the intervention, with few capacity issues, although there was some evidence that staff misremembered key points from the EC training and facts around their use. Some challenges were highlighted in one UC centre, but this is reflective of the unique challenges of this centre and not the UC intervention.

Objective 5: assess the potential efficacy of supplying free electronic cigarette starter kits

The offer of a free EC starter kit was well accepted by staff and participants. Using ITT analysis, we found sustained 24-week abstinence rates of 0% in the UC arm and 6.25% in the EC arm, which provides preliminary evidence of potential efficacy; however, the absolute numbers were small (3/48 in the EC arm and 0/32 in the UC arm). The UC sample size was also lower than expected; the 0% abstinence rates may therefore be an underestimate of true cessation rates with UC.

Objective 6: explore the feasibility of collecting data on contacts with health-care services among this population as an input to an economic evaluation in a full cluster randomised controlled trial

Almost all participants who were present at follow-up visits provided data on health-care service utilisation and HRQoL measures; however, as reflected in our interview data, some participants found this data collection intrusive or the questionnaires overly complicated.

Objective 7: estimate the cost of providing the intervention and usual care

Although it was feasible to collect information relating to the cost of delivery in the EC arm, collecting data from staff about contact time was not always possible in the UC arm.