At the end of the 6-month follow-up period in each SSS, valid data of attendance were collected from the SSSs using NHS monitoring data collected by smoking cessation advisors. A list of participants recruited from the particular SSS was sent to the local collaborator, who searched their user database for each participant named. For each participant whose name was present in the database, and had attended the service between the study entry date and the 6-month follow-up date, a case report form was completed. Data were collected on dates of attendance, agreed quit date, 4-week follow-up date, total number of sessions attended and treatment outcome. We also collected data on the type of advisor, the type and setting of support received, and pharmacological support used.
Research interviewers, independent from the service providers, conducted a computer-assisted telephone interview 6 months after the date of randomisation to assess self-reported SSS attendance, current smoking status, daily cigarette consumption, reasons for non-attendance and barriers to attendance in all participants.
Procedures were applied to maximise retention of participants at the 6-month follow-up. Interviewers made a maximum of 10 attempts to contact a participant by telephone. If, after 10 attempts, the interviewers had been unable to speak to a participant in person, they sent a text message prompting a response back to the mobile phone from which it was sent. The participant was sent the same message a second time if no response was received after 3 days, and, if no response was received after a further 3 days, the participant was sent a paper version of the follow-up questionnaire to complete and return by post. The paper questionnaire was also sent to participants unable to complete the telephone interview but willing to complete and return a postal questionnaire. A decision was taken late on in the trial to send a reminder for this postal questionnaire. If a participant did not fully complete or did not wish to complete the telephone interview, the interviewer attempted to ask the participant four basic questions most relevant to the primary and main secondary outcome.
Participants claiming 7-day abstinence at the 6-month follow-up were asked to provide a salivary cotinine sample to biochemically validate 7-day point prevalent smoking cessation.47Samples were obtained by
post using a saliva sample kit.48Use of NRT at the time the sample was taken was assessed by questionnaire,
as the cotinine content can be affected by continued use, and taken into account when the results of the analysis were received. To maximise return of samples, a £5 Marks and Spencer voucher was included with
each kit, and a further £5 voucher was sent on return of the sample. Participants were contacted by a research interviewer to remind them to return their kit if saliva samples were not returned within 7 days, and after 10 unsuccessful attempts to contact the participant, they were sent a reminder text message. If the interviewer was successful in contacting the participant but their sample was still not returned after 7 days, the participant was sent the same reminder text message.
Figure 1shows detail of the timing of assessments, intervention and follow-up.
Measures
Baseline measures
Inclusion criteria (age, intention and motivation to quit, and previous SSS attendance), demographics (gender, marital status, qualifications, employment and ethnicity), self-reported health, dependence on nicotine (number of cigarettes per day and time from waking to first cigarette), smoking history (age started and previous quit attempts), determination and confidence to quit were assessed in the baseline screening questionnaire.
Outcome measures
Primary outcome
The proportion of people entering the smoking cessation service (i.e. attending the first session of a 6-week course) over a period of 6 months from the receipt of the invitation letter, as measured by the NHS records of attendance at the SSSs.
Secondary outcomes
1. Seven-day point prevalent abstinence at the 6-month follow-up, validated by salivary cotinine for all participants reporting abstinence in both the intervention and control groups.
2. Additional periods of abstinence measured by self-report only: 24-hour and 7-day point prevalent, 1- and 3-month prolonged abstinence.
3. Three-month prolonged abstinence, measured by self-report and validated.
4. Self-reported changes in daily cigarette consumption, quit attempts, and changes in motivation and intention to quit in continuing smokers.
5. The number completing the 6-week NHS course.
Process measures
1. The number of smokers attending the taster session (intervention group only). 2. Self-reported attendance data.
3. Perception of the taster session.
4. Perception of the personal invitation letters.
5. Reasons for non-attendance at the taster session and barriers to attendance at the NHS services. The number attending the taster sessions was taken from records, all other process measures were included in the follow-up interview 6 months after the date of randomisation. Perception of the taster session was also assessed by an evaluation form immediately after each session.
Reasons for non-attendance at the taster session and barriers to attendance at the NHS services were assessed using open questions. In addition, all participants who reported not attending the SSS were asked to complete the 40-item Treatment Barriers Questionnaire (TBQ), validated on a US population,49to assess
Health economic measures
The economic component estimated the cost of providing the interventions, using primary cost data from a NHS and Personal Social Services perspective, as recommended by National Institute for Health and Care Excellence (NICE) guidance.50We also measured patients
’use of health and social care services using a comprehensive service use questionnaires. Quality-adjusted life-years (QALYs) were calculated from the European Quality of Life-5 Dimensions (EQ-5D) questionnaire using the area-under-the-curve method.51
A cost-effectiveness analysis (CEA) was undertaken to compare the tailored letter plus the taster session and the generic letter. In addition to the within-trial CEA, lifetime health-care cost savings and QALY gains associated with the two interventions were estimated based on a decision-analytic model.52