Effectiveness of nicotine salt vapes, cytisine, and a combination of these products, for smoking cessation in New Zealand: protocol for a three-arm, pragmatic, community-based randomised controlled trial

BACKGROUND: Combining short-acting nicotine replacement therapy with varenicline increases smoking cessation rates compared with varenicline alone, but not all people tolerate these medications or find them helpful. We aim to investigate the therapeutic potential of an analogous combination, by evaluating the effectiveness, safety, and acceptability of combining nicotine salt e-cigarettes with cytisine, compared to nicotine salt e-cigarettes or cytisine only, on smoking abstinence at six months. METHODS: A pragmatic, community-based, investigator-blinded, randomised superiority trial design will be utilised. Eligible participants will be people who smoke daily (N = 800, 90% power) from throughout New Zealand, who are: aged ≥ 18 years, motivated to quit in the next two weeks, able to provide online consent, willing to use e-cigarettes and/or cytisine, and have daily access to a mobile phone. Recruitment will utilise multi-media advertising. Participants will be randomised (3:3:2 ratio) to 12 weeks of: 1) e-cigarettes (closed pod system, 3% nicotine salt, tobacco flavour) plus cytisine; 2) e-cigarettes alone, or 3) cytisine alone. All groups will receive a six-month, text-message-based behavioural support programme. The primary outcome is self-reported, biochemically verified, continuous abstinence at six months post-quit date. Secondary outcomes, measured at quit date, then one, three, six, and 12 months post-quit date, include self-reported continuous abstinence, 7-day point prevalence abstinence, cigarettes smoked per day, withdrawal and urge to smoke, time to (re)lapse, treatment use and compliance, treatment crossover, dual-use, use of other cessation products, change in e-cigarette products, continuation of product use, acceptability, change in health state, health-related quality of life, change in body mass index, adverse events, and cost per quitter. DISCUSSION: Pragmatic trials are of particular value as they reflect the ‘real world’ impact of interventions. The trial will provide some of the first evidence on the effectiveness of combining nicotine salt e-cigarettes with cytisine for smoking cessation, in a country with strong tobacco control policy. Findings will be incorporated into relevant systematic reviews, informing practice and policy. TRIAL REGISTRATION: NCT05311085 ClinicalTrials.gov. Registered 5th April, 2022.