In the European Union, with Sweden as the only exemption, snus has been banned since 1992. Norway is not a member of the EU and as such is not affected by the snus ban. Recently we have observed a significant decline in smoking prevalence in Norway, among both men and women and in all age groups. A corresponding increase in snus use has been observed, in particular among young men, where the decline in smoking has been particularly evident [1]. This resembles the situation in Sweden, where cigarette use has declined dramatically over time while snus use has been at a high level or increasing. A relationship between the increase in snus use and the decrease in smoking has been suggested [2, 3], but is strongly debated [4]. Recent data from Norway has indicated that many smokers are using snus as a method for quitting [5, 6]. Several studies based upon observational data have reported high success rates among men who have used snus as a method for quitting smoking. One such study was Ramstrøm & Foulds' [7] analysis of data from a cross-sectional survey made in Sweden in 2000-2001, where they found a success rate of 66% among men who had used snus as a single aid, as compared with 47% among nicotine gum users (OR 2.2, 95% CI 1.3-3.7) or 32% for those using the nicotine patch (OR 4.2, 95% CI 2.1-8.6), Giljam & Galanti [8] found in a retrospective survey of Swedish smokers and ex-smokers that having used snus at the latest quit attempt increased the probability of being abstinent by about 50% (OR 1.54, 95% CI = 1.09-2.20). In the US, Rodu & Phillips [9] compared methods used in last quit attempts from cross-sectional survey data from year 2000, and they also found higher success rates for people who used snus to quit smoking (73% of these were no longer smokers at the time of the survey) compared to people who had used nicotine gum (34% former smokers) or nicotine inhalers (28% formers smokers). A recent study among Norwegian males aged 20-50 based upon retrospective questions about use of cessation methods showed that the odds ratio for abstinence from smoking at the time of the survey was 2. 68 (p < .001) for those who had used snus compared with those who had used nicotine chewing gum [5].

In recent years a growing number of studies and systematic reviews have concluded that use of snus is substantially less hazardous than cigarette smoking [10, 11]. This conclusion was also reached by the only systematic review of the evidence from studies that allow direct comparison of relative risk of smoking and snus in the same populations [12]. The magnitude of the overall reduction in hazard is difficult to estimate, but it is at least 30% for pancreatic cancer, at least 50% and probably more for oral and other gastrointestinal cancer, and possibly 100% for lung cancer and chronic obstructive pulmonary disease [10]. A study using a modified Delphi approach (judgment by a panel of experts) to estimate the relative hazard concluded that snus was likely to be at least 90% less harmful than smoking [13]. A simulation model based, among other things, on these estimates of risk showed that the switch from smoking to snus represented only a very minor difference in survival compared to smokers who gave up all use of tobacco [14]. Given the increasing evidence that snus and cigarettes have very different impact on user's health, tobacco harm reduction is increasingly seen as a promising approach to reduce the major public health problem that smoking still represents [15, 16]. Harm reduction in a tobacco frame implies actively encouraging inveterate smokers to switch to safer sources of nicotine, such as e.g NRT and snus. Substituting cigarettes with NRT or snus facilitates risk reduction by allowing smokers to become smoke-free without abstaining from nicotine or tobacco respectively, but complete abstinence is still achievable [5, 7, 17]. There is a great deal of political controversy connected to the issue of harm reduction, also in Scandinavia, where the health authorities have stated that they do not want to recommend smokers to switch to snus or use snus as a method for smoking cessation [18].

The aim of this study was to assess the extent to which snus has been used as a method for quitting smoking among Norwegian males and females, compared to other methods such as use of NRT, according to the year the quit attempt was made. Another aim has been to study the association between methods for quitting and socio-demographic background, smoking history and current snus consumption. Finally, quit rates for smoking and continuation of snus use after quitting smoking have been investigated.

The data used for this study were drawn from a larger set of yearly representative cross-sectional surveys on tobacco behaviour conducted by Statistics Norway (SSB) on behalf of the Norwegian Directorate of Health. These surveys have been conducted every year since 1973, with a base of core questions on smoking behaviour repeated yearly. Questions on the use of methods for quitting smoking were first asked in 2003. For this study, data from 2003 to 2007 were pooled, producing a sample of 6256 respondents. The average response rate for these years was 65%. The material and methods in these surveys have previously been described by Lund and co-workers [6].

The findings from this study show that snus was used by many male smokers in Norway to help their efforts to quit smoking. Among women, NRT was the most common method used of those included in the study, while snus was not widely used. Stratifying the data according to the year of quitting smoking indicated a significant increase over time in the use of all the methods asked about to quit smoking, among both women and men. The total increase was greatest for men, and use of snus accounted for most of it. Lindstrøm [19] found the same trend in a similar analysis based on retrospective data from Sweden. In addition to gender and current snus use, age was the variable most clearly associated with using snus as a method for quitting in this study. In the youngest group of men in our sample, snus had been used in as many as half of the most recent attempts to quit, as compared to around seven per cent among men above the age of 45.

Consistent with results from other observational studies of the use of snus for quitting smoking [5–9, 20] our data also indicated that snus can be an effective method to quit smoking. Among those who had quit smoking, it was more likely that on their last attempt they had used snus than NRT. One possible explanation for this could be the ability of snus to provide nicotine-addicted smokers with similar, satisfying levels of the drug. Compared to NRT, nicotine uptake from snus resembles that when smoking cigarettes [21]. In addition to snus providing nicotine in a way that is likely to satisfy the former smoker; it is also possible that snus provides some partial substitution for the sensory and social aspects of smoking. In contrast to nicotine replacement products, the use of snus may e.g be experienced by smokers as replacing some of the social functions that cigarettes had, in that that brand choice, visibility and rituals of use can represent social positioning and self presentation [22]. High consumer acceptability produced by these characteristics of snus can be some of the reason why so many Norwegian smokers prefer snus as a method for quitting, as well as for the higher quit rates for smokers who use snus as aid for quitting compared to NRT.

Our results also show that many of the smokers who quit smoking assisted by snus continued to use the product after their quit attempt. It is most likely an inevitable effect of switching to snus as a method for smoking cessation that some smokers who could have become abstinent will continue to use nicotine, but these snus users will be using nicotine in a low-risk form. Also, it should be emphasized that a considerable fraction (31.2%) of those who had used snus to quit in this study did end up completely tobacco free, as observed also in other observational studies from Scandinavia [5, 7]. Still, to advise smokers to use snus as a method for quitting as a general strategy may not be sensible against this background. Another argument against this is the potential implications it may have for countries where use of smokeless tobacco is rare, or where the smokeless tobacco available is far more toxic than snus.

This study has several limitations. First, it is important to point out that our data only informs about methods used at the latest quit attempt, thus we cannot draw firm conclusions about overall changes in use of aids at quit attempts among Norwegian smokers. A possible limitation of the findings about quit attempts dating back in time, is that respondents' recall of their cessation process may be less accurate than in the in the cases where the experience is more recent. Several studies that have measured agreement between retrospective and contemporaneous reports on variables such as smoking rates [23] age of tobacco initiation [24], smoking during pregnancy [25] and levels of nicotine dependence [26], have concluded though that the validity of retrospectively reported information about smoking is acceptable. Further, the pooling of data across age groups could have introduced some uncertainty concerning how much of the age effects observed are produced by age compared to by cohort and time period. Given that the time span of the data collection is only four years, this is however not likely to be a large problem. Finally, it is important to assert the possibility that confounding factors that we have not included in the analyses may have contributed to the differences in efficacy between snus and NRT that our findings show. For example, those using snus in this study may been more quit-motivated or less dependent former smokers or different in some other way that was not measured. To explore this further, randomized controlled studies (RCT) comparing the outcome of quit attempts assisted by snus versus other methods would be helpful. To date, few RCT's have been carried out to assess the use of smoking cessation, but recently, a randomized, double-blind placebo-controlled clinical study from Serbia reported that participants who had used snus as an aid for cessation were more likely to quit smoking completely than the controls; the odds ratio (snus versus placebo) for the protocol estimates of cessation varying between 1.9 to 3.4 [27]. On the other hand, it should be noted that observational studies provide data that are superior to RCT's when it comes to evaluating effectiveness under real life conditions for different smoking cessation methods.

In conclusion, the findings of this study, considered alongside the information already published, indicate that encouraging smokers to switch to snus could be beneficial to public health. Even though there are obvious reasons to be cautious about promoting snus as a general strategy for smoking cessation, snus could be useful for smokers who are less likely than others to successfully quit, either because they are more likely to fail when they try or because they are not inclined to try.