Original research abstinence rates were defined as answering ‘no’ to the question “‘Have you smoked a tobacco cigarette in the past 7 days?” Secondary outcomes were self-reported 7-day point preva- lence smoking status at 1 and 3 months, biochemically-validated 7-day point prevalence abstinence at 6 months, number of quit attempts, time to relapse (if applicable), number of cigarettes per day, nicotine dependence, 15 number of times using an e-cig- arette per day, incidence of self-reported dry cough or mouth or throat irritation, motivation to stop smoking, 16 self-reported use of healthcare services in the last 6 months, self-reported use of smoking cessation services in the last 6 months and quality of life (using the EQ-5D-5L). 17 Adverse events were self-reported by participants in the follow-up questionnaire in response to the experience of symp- toms of a dry cough and throat/mouth irritation. Attendance at hospital was asked about at 1, 3 and 6 months. Further details of secondary outcomes and adverse events are available in the published protocol. 9 Sample size A sample size of 972 (486 per group) conferred 90% power to detect a difference between a biochemically-confirmed control quit rate of 6.2% and biochemically-confirmed intervention quit rate of 12.2% at the 5% level of significance. This was based on a US trial of an ED smoking cessation intervention using a brief intervention, referral to smoking cessation services and nicotine replacement. 18 A quit rate of 6.2% was used in the control group based on an average of three studies of unmotivated quitters who received either contact details for stop smoking services or no intervention. 19–21 Statistical analysis The primary outcome measure was compared between the two groups using a binary regression model with a log link to esti- mate the relative risk and with an identity link to estimate the difference in risk; both models included fixed effects for rando- misation group and site. In cases when the convergence failed for the identity link model, a Gaussian model with robust variance was used. Full details of the statistical analysis can be found in the statistical analysis plan online. 10 Those conducting the anal- ysis were not blinded. Patient and public involvement This trial was initially informed by patient and public involve- ment (PPI) consultations in three EDs, assessing the acceptability and feasibility of approaching people about smoking cessation. We actively recruited further PPI volunteers who were then involved in trial set-up through advising on study materials, checking Case Report Form burden and advising on language use. A separate PPI panel was recruited to inform intervention components (choice of e-cigarette). We recruited two indepen- dent PPI members to be involved in our trial steering group, providing a lay perspective in oversight of the trial. We have shared the results with all our PPI representatives.
The most common reasons for declining to take part were: no reason given (n=409, 29.1%), feeling too unwell (n=296, 21.0%) and not wanting to quit (n=161, 11.4%). The most common reasons for being excluded were providing a CO reading of <8 ppm (n=308, 65.8%), currently using an e-ciga- rette daily (n=52, 11.1%) and not smoking daily (n=31, 6.6%). Three participants were found later to be ineligible and were considered post-randomisation exclusions, two due to being randomised twice and one who subsequently reported daily use of an e-cigarette. There were 5 (1.0%) withdrawals in the intervention group and 12 (2.5%) in the control group. Reasons for withdrawals were no reason given (n=7), wanting the intervention (n=3), did not want to answer the questions (n=6) and reporting a new allergy to nicotine (n=1). The baseline characteristics of the participants are shown in table 1 and were broadly equivalent across the two groups. The mean deprivation decile was 4.31 in the intervention group and 4.53 in the control group (1=most deprived, 10=least), indi- cating that participants were generally from more deprived neighbourhoods than average. Primary outcome Biochemically-verified self-reported continuous abstinence at 6 months was 7.2% (35/484) in the intervention group and 4.1% (20/488) in the control group (relative risk (RR) 1.76 (95% CI 1.03 to 3.01), risk difference 3.3% (95% CI 0.3% to 6.3%)). In total, 351 (72.5%) participants in the intervention group and 317 (65.0%) in the control group reported their smoking status at 6 months (figure 1). Of those who reported continuous abstinence, 35/122 (28.7%) in the intervention group and 20/64 (31.3%) in the control group went on to have their abstinence Figure 1 Trial profile. *Where the person accompanying an included patient met the inclusion criteria and wished to participate, they were enrolled in a similar way to the patients and assigned to the same treatment group as the patient they accompanied. They were followed up but are not included in this analysis.
RESULTS Participants
Between January and August 2022 we screened patients in the ED of whom 2888 reported current smoking; 1443 agreed to take part in the trial and were assessed for eligibility and 484 were subsequently randomised to the intervention group and 488 to the control group (figure 1).
Pope I, et al . Emerg Med J 2024; 41 :276–282. doi:10.1136/emermed-2023-213824
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