Study protocol for a randomised controlled trial of electronic cigarettes versus nicotine patch for smoking cessation

Background: Electronic cigarettes (e-cigarettes or electronic nicotine delivery systems [ENDS]) are electrically powered devices generally similar in appearance to a cigarette that deliver a propylene glycol and/or glycerol mist to the airway of users when drawing on the mouthpiece. Nicotine and other substances such as flavourings may be included in the fluid vaporised by the device. People report using e-cigarettes to help quit smoking and studies of their effects on tobacco withdrawal and craving suggest good potential as smoking cessation aids. However, to date there have been no adequately powered randomised trials investigating their cessation efficacy or safety. This paper outlines the protocol for this study. Methods/design: Design: Parallel group, 3-arm, randomised controlled trial. Participants: People aged >= 18 years resident in Auckland, New Zealand (NZ) who want to quit smoking. Intervention: Stratified blocked randomisation to allocate participants to either Elusion (TM) e-cigarettes with nicotine cartridges (16 mg) or with placebo cartridges (i.e. no nicotine), or to nicotine patch (21 mg) alone. Participants randomised to the e-cigarette groups will be told to use them ad libitum for one week before and 12 weeks after quit day, while participants randomised to patches will be told to use them daily for the same period. All participants will be offered behavioural support to quit from the NZ Quitline. Primary outcome: Biochemically verified (exhaled carbon monoxide) continuous abstinence at six months after quit day. Sample size: 657 people (292 in both the nicotine e-cigarette and nicotine patch groups and 73 in the placebo e-cigarettes group) will provide 80% power at p = 0.05 to detect an absolute difference of 10% in abstinence between the nicotine e-cigarette and nicotine patch groups, and 15% between the nicotine and placebo e-cigarette groups. Discussion: This trial will inform international debate and policy on the regulation and availability of e-cigarettes. If shown to be efficacious and safe, these devices could help many smokers as an alternative smoking cessation aid to standard nicotine products.