Walker et al. BMC Public Health 2011, 11:37 http://www.biomedcentral.com/1471-2458/11/37 Background Smoking is the leading cause of lost healthy life years in New Zealand. In 1990, 28% of New Zealand adults smoked, with this figure dropping to 24.9% in 1996/7, 24.5% in 2002/3 [1] and 19.7% in 2006/7 [2]. In Māori (indigenous New Zealanders) there has been little down- ward trend in smoking prevalence since the early 1990’s, with 45.5% of Māori smoking in 1996/7, and 47.2% smoking in 2002/3 [2]. However, in 2006/7 there was a sharp fall in smoking prevalence in Māori, down to 38% [2]. Despite this recent evidence of change, based on the current rate of progress it is estimated that it will take 100 years before the adult smoking rates in New Zealand reach 3.6%, the level of all New Zealand doctors now smoking [3]. New approaches to smoking cessation are urgently needed, ideally ones that give additional ben- efits to existing strategies. One approach that warrants further investigation is to look at ways of reducing the association between smoking and nicotine delivery. Nicotine is the constituent of tobacco principally responsible for the addictive nature of cigarette smok- ing. Reward pathways in the brain are stimulated within two to three minutes of inhalation. The smoker is com- pelled to continue dosing throughout the day to main- tain the desirable effects of nicotine and mitigate feelings of withdrawal [4]. Other factors, besides nico- tine, may also play a part in the dependency-forming aspects of smoking, including the effects of other chemi- cals in tobacco smoke, the strong behavioural/tactile association of smoking and the social pleasure of smoking. There is some evidence that progressive reduction in the level of nicotine in cigarette tobacco can reduce the level of nicotine dependence in smokers, with minimal compensatory smoking and without any negative health effects [5]. Reduced nicotine cigarettes have been pro- duced in the past (as the Quest brand marketed by Vec- tor Tobacco Inc, USA), with the tobacco altered through genetic modification. Quest 1, 2 and 3 cigar- ettes have a nicotine yield of 0.6 mg, 0.3 mg and ≤0.05 mg per cigarette respectively, an average nicotine content of 8.9 mg, 5.1 mg and 1.0 mg per cigarette respectively, and a tar content of 10 mg per cigarette (similar to the level in regular cigarettes). These cigar- ettes are no longer commercially available, but are avail- able for research purposes. The use of Quest 3 cigarettes, so called nicotine-free cigarettes, warrant further scientific investigation, as current evidence sug- gests that the use of nicotine replacement therapy (NRT) in combination with such cigarettes may have a greater impact on the signs and symptoms of withdra- wal and cessation rates, compared to the use of nico- Page 2 of 8 tine-free cigarettes alone [5]. However, there is a need to undertake adequately powered clinical trials to clarify the true strength and direction of the above association, with at least six months follow-up data collected. Methods/design Objectives The primary objective of this trial is to determine the combined effect of nicotine-free cigarettes and NRT (used immediately after quitting), on long-term quit rates. Secondary objectives include whether such an intervention is cost effective and acceptable. Study design This study is a parallel, randomised controlled clinical trial, with allocation concealed from the study researchers. Study population The study population will be registered and eligible call- ers to the national toll-free Quitline cessation service. Inclusion criteria Participants will be smokers from throughout New Zeal- and who want to stop smoking. Participants will be eli- gible provided they: are at least 18 years of age, have their first cigarette within 30 minutes of waking, are able to provide verbal consent, and have a telephone. Exclusion criteria Pregnant women and women who are breastfeeding will be excluded from the trial. People will also be excluded from the trial if they meet any of the following criteria: current users of NRT products; current clients of Txt2Quit and NRT Online (current Quitline services); current users of non-nicotine based cessation therapies (e.g. buproprion, clonidine, nortriptyline or varenicline); they only use non-cigarette tobacco products (e.g. pipes, cigars); they have had a myocardial infarction within the last two weeks; and have had angina, severe cardiac arrhythmia or a stroke in acute phase within the last two weeks. The medical conditions above are listed con- traindications for the use of NRT patch, gum, and lozenge. A number of disease conditions are known where precautions for the use of NRT products are indi- cated, such as severe cardiovascular disease (occlusive peripheral arterial disease, cerebrovascular disease, stable angina pectoris, and uncompensated heart failure) and vasospasm, uncontrolled hypertension, renal or hepatic impairment, active duodenal ulcers and gastric ulcers. Quitline staff will ask potential participants about these conditions, prior to participant randomisation.