Walker et al. BMC Public Health 2011, 11:37 http://www.biomedcentral.com/1471-2458/11/37 (i.e. 25% or more), the cost per person reducing their daily cigarette consumption will be calculated. Differ- ent approaches to assessing the benefit of years per life saved - including the use of New Zealand specific data on the relative risk of death as per Hunt et al 2005 [12], will also be explored. Tolerability All randomised participants who receive at least one dose of study treatment or control will be included in the planned analyses. Comparison of the frequency of treatment withdrawal between the treatment and the control group will be tested using Chi-square statistics. The numbers of participants discontinuing treatment prematurely for any reason will be summarised by treat- ment group and by reasons for discontinuation. Serious adverse events will be coded using ICD-10 AM codes. The incidence of all suspected serious adverse treatment reactions will be summarised by treatment group. Procedures to account for missing data For treatment effects, sensitivity analysis will be carried out to determine the effect of missing data (such as par- ticipants lost to follow-up). All participants lost to fol- low-up will be presumed to be smoking [13]. Ethics Ethics approval has been granted from the National Multi-Regional Ethics Committee (Ethics number MEC/ 08/10/117). Maintenance of confidentiality and compli- ance with New Zealand’s Privacy Leglisation will be emphasised to all study participants. Participation in the study is entirely voluntary. Verbal consent will be obtained at the time of contact with Quitline, however a written consent form and patient information sheet will be posted out to participants for their information. Data will be entered, stored and backed-up in a secure man- ner via the Unit’s internet data management system. Participants will be acknowledged in all publications and presentation of the results. Discussion Increasing quit rates would have a significant positive impact upon the health and well-being of smokers and their households [14]. Unfortunately many smoking cessation aids on the market are relatively expensive, have side effects and are only moderately efficacious. There would be great interest in a novel smoking ces- sation aid that may be an addition to current therapies or indeed could be used by those who do not want to or can’t use NRT or other cessation pharmacothera- pies. Initial studies have shown that reduction in expo- sure to nicotine in cigarettes can reduce the level of nicotine dependence in smokers, at least in the short term, and that combined use of reduced nicotine cigar- ettes and NRT appears more effective at increasing Page 7 of 8 quit rates than using reduced nicotine cigarettes alone or NRT alone [5]. However, larger and more long-term studies are still needed to clarify the strength of this relationship. If the combined use of nicotine-free cigarettes and NRT is shown to have a positive impact on smoking cessation and is cost effective, further research would focus on the implications of the research findings on policy. Smoking prevalence has changed little in recent years in New Zealand. Clearly the current range of smoking cessation aids are not having a strong enough impact upon smoking cessation rates and consequently additional options for smokers who want to quit are needed. This trial will test the balance of benefits and risks of a new strategy for people to overcome nicotine dependence. Since smoking is the leading cause of lost healthy life years in New Zealand [1] if proven effective this strategy has the potential to have substantial public health benefits. Acknowledgements This trial is funded by a programme grant from the Health Research Council of New Zealand. The design, conduct, analyses and interpretation of the trial will be made independent from the trial sponsor. We thank Stella McGough at the Quit Group, the research assistants at The Quit Group (Lynn Szpetnar, Elizabeth Cameron, Elspeth Chell), study related staff at the Clinical Trials Research Unit (Nathan Cowie, John Fa’atui, Stephen Boswell, Micheal Ng, Joy Jiang, Johan Strydom, Terry Holloway, Lyn Cummings, Mary Cosson, and Sheila Fisher), and Professor Anthony Rodgers (George Institute, Sydney, Australia). Author details 1Clinical Trials Research Unit, School of Population Health, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. 2Previous Address: The Quit Group, PO Box 12605, Wellington, New Zealand. 3Current Address: Litmus, Wellington, New Zealand. 4Centre for Tobacco Control Research, Social & Community Health, School of Population Health, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. 5Previous Address: Clinical Trials Research Unit, School of Population Health, The University of Auckland, Private Bag 92019, Auckland, New Zealand. 6Current Address: Queen Mary University of London, Wolfson Institute of Preventive Medicine, Barts and The London School of Medicine and Dentistry, Charterhouse Square, London, EC1M 6BQ, UK. 7Health NZ Ltd., 36 Winchester St, Lyttelton, Christchurch 8082, New Zealand. 8Statistics Department, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Authors’ contributions NW, CB, MGr, MGl, HM, ML, SVH, and RW conceived the original idea for the trial, sought funding and wrote the protocol. CH and MGr manage the day to day running of the trial, including participant follow-up. This protocol paper was written by NW, with input from all co-authors. All authors read and approved the final manuscript. NW will act as guarantor for this paper. Competing interests The nicotine-free cigarettes (Quest 3) used in this trial have been purchased from Vector Group Ltd, USA. NRT patches, gum and/or lozenges used by all study participants after Quit day are purchased by participants (using the subsidized Quit Card they receive from Quitline) from community pharmacies. No authors have received support from any companies for the submitted work. No authors have any relationship with Vector, a company that might have an interest in the submitted work. HM has received honoraria for speaking at research symposia and received benefits in kind and travel support from, and has provided consultancy to the manufacturers of smoking cessation medications. CB and HM have previously undertaken