Walker et al. BMC Public Health 2011, 11:37 http://www.biomedcentral.com/1471-2458/11/37 and whether the six weeks use of the cigarettes was adequate. The number of nicotine-free cigarettes and normal cigarettes smoked each week during the intervention period will also be recorded. Information related to the use of the NRT: Partici- pants will be asked about their use of NRT during the treatment period. The following secondary outcome measures will be assessed in all participants at three weeks, six weeks, three months and/or six months after the Quit date: The physical signs and symptoms associated with withdrawal at three and six weeks: Measured using the Mood and Physical Symptoms Scale (MPSS) [7]. Additional withdrawal questions will also be asked related to the frequency of disturbed sleep, anxiety, mouth ulcers, cough, impatience, dizziness and increased dreaming [8]. Self-rated chances of quitting at three and six weeks: Measured on a scale of one to five, where one is very low and five is very high. Proportion of participants who have stopped smoking at three weeks, six weeks and three months: Defined as no nicotine cigarettes (not even a puff) in the past seven days. Continuous abstinence: Defined as self-report of smoking no more than five nicotine cigarettes from the Quit date, collected at all time points. Proportion of participants who have significantly reduced daily smoking level at six months: Defined as reducing consumption by at least 25% (in terms of numbers of cigarettes per day or weight of loose tobacco per day). Number of cigarettes currently smoked per day: If the participant is still smoking (all times points). Pack size (and how long pack lasts) if smoking roll- your-owns. Cost information: Cost outcomes will include cost per quitter, cost per person reducing their daily cigarette consumption, and cost per Quality Adjusted Life Year of life saved among quitters. The tobacco expenditure savings to individual smokers will also be calculated using data on the daily amount smoked prior to quitting and the price of the particular products smoked. Use of NRT: Participants will be asked about con- tinued use of any NRT (including type, dosage, fla- vour, and frequency of use) at all time points. Use of non-NRT methods of cessation at six months: Participants will be asked about their use of non-NRT methods of cessation such as buproprion, clonidine, nortriptyline, varenicline, acupuncture etc. Page 5 of 8 Alcohol use and abuse at six months: Measured using the AUDIT-C [9]. Serious adverse events: Information regarding any serious adverse events and whether they are related to treatment will be collected at all time points. Concomitant medication: collected at all time points Sample size A sample size of 1,410 people (705 in each group, with a loss to follow-up rate of 20% and at least 25% Māori in the sample) is required for this trial. This number will provide 90% power at p = 0.05 to detect a difference in point prevalence abstinence of 7.5% at six months. In addition, this sample size will allow the consistency of effects for pre-specified subgroups to be assessed. It is expected to take 18 months to recruit the required sam- ple size, based on a previous cessation trial run through the New Zealand Quitline [10]. Withdrawal criteria If, at any time after randomisation, significant intoler- ance to the study treatment is suspected, the treatment (or control) can be withdrawn. Should participants require discontinuation of study treatment for any rea- son (see below), or if they elect to cease taking treat- ment, follow-up calls and data collection will continue as scheduled as if they were continuing with the rando- mised treatment. Participants may have the study treat- ment withdrawn if one or more of the following occurs: The participant makes a voluntary decision to withdraw from follow-up, or from the treatment. The participant has any serious clinical adverse event, intercurrent illness, or other medical condi- tion that indicates to the principal investigator that continued treatment with the study treatment is not in the best interest of the participant. The study treatment will be withdrawn if the participant devel- ops any life threatening or seriously disabling illness or is admitted to hospital. The participant becomes pregnant during the course of the trial. Such participants will be asked to discuss on-going NRT use with their general practi- tioner or lead maternity caregiver. The investigator feels that it is in the best interests of the participant. The study is terminated. If the participant discontinues treatment due to a ser- ious adverse event, the participant will be followed until the event resolves or there is a return to a clinically acceptable medical status. Participant deaths or serious