Smoking is the most important single cause of morbidity and mortality in industrialised countries [1]. Because smoking prevention will not affect tobacco-related mortality until the second half of the 21^st century, quitting by current smokers is the main way to achieve positive effects on mortality in a medium term [2]. Many smokers are interested in quitting. More than 70% of all smokers try to quit smoking at least once in their lifetime [3]. In the United States, 40% of all smokers reported that they had tried to quit within the last 12 months [4], and 70% reported that they wanted to quit [5]. In Germany, lower rates were found. Only 34% reported at least one quit attempt within the last 12 months, and 43% said that they wanted to quit [6].

To support smokers in their quit attempts, a wide range of smoking cessation aids (SCA) is available. SCA comprise methods and products to assist smokers in quitting through coping with psychological or physical aspects of nicotine dependence. Meta-analyses have shown that smoking cessation courses, nicotine replacement therapy, and bupropion can significantly increase success rates in quitting [7]. Even minimal interventions such as self-help materials have a small effect when compared with no intervention [8]. In contrast to the evidence about the efficacy of SCA, less than 23% of current smokers actually use SCA when trying to quit smoking according to general population studies in the US [9, 10]. In Germany, 19% have used SCA in at least one quit attempt during their lifetime [11]. The question arises why smokers do not sufficiently use available SCA. Therefore, we assessed reasons for not using SCA in smokers who reported an unaided quit or reduction attempt.

A limited number of studies investigating the utilisation of SCA compared users and non-users. Those studies [10–12] found that the use of SCA is more likely among women, older persons, and persons with more than 12 years of education than among men, younger persons, and persons with less than 12 years of education. Smoking more cigarettes per day, having had more quit attempts in the past, and a higher Fagerström Test for Nicotine Dependence score were positively associated with SCA use. Furthermore, smokers utilising SCA are more frequently allocated to stages with enhanced motivation to stop smoking [11]. In the current study, we therefore examined whether demographic, smoking behaviour, and motivational variables predict the reasons for not using SCA among smokers reporting an unaided quit or reduction attempt. It has been shown that smoking more cigarettes per day, having a higher degree of nicotine dependence, and less quit attempts in the past are associated with less success in quitting smoking [13]. Furthermore, the efficacy of nicotine replacement therapy has been proven mainly for smokers smoking more than 10–15 cigarettes per day [14]. Thus, smokers with an unfavourable smoking behaviour (heavier smokers) are most likely to benefit from the use of SCA. Therefore we furthermore investigated whether the reasons for non-use vary between heavy and light smokers.

Among the 1,632 daily cigarette smokers, 361 (22.1%) had ever used SCA. Among the remaining 1,238 never-users (33 smokers did not provide any information about SCA use), 636 (51.4%) reported a quit or reduction attempt within the last 12 months and were therefore eligible for the present analyses. Those 636 participants were on average 38.25 (SD = 14.92) years old, 53.1% were male. Most of them (66.2%) had at least 10 years of school education and 72.5% were married or lived in a stable partnership. The number of cigarettes smoked per day ranged from 1 to 45 (mean 14.99; SD = 7.17), the mean FTND score was 2.84 (SD = 1.98) and 62.4% intended to quit within the next six months.

The most frequently endorsed reasons for not using SCA were "I thought I would be able to quit or reduce smoking on my own" (55.2%), "I thought that I did not need these aids" (40.1%) and "I had the feeling that smoking did not constitute a big problem in my life" (36.5%). One quarter agreed that SCA would not help them to stop or reduce smoking, that nothing would help in trying to stop or reduce smoking, that SCA would cost too much, and that they did not want to admit to themselves that they needed these aids (Table 1). The most frequently opposed reasons were "I was worried what other people would think about me" (84.1%), "It was unpleasant or embarrassing to use the aids" (78.7%) and "I did not feel able to talk to others about my smoking" (78.2%).

The main finding is that the reasons for not using SCA can be seen in attitudes and beliefs of the smokers towards smoking cessation and SCA rather than in social and environmental barriers. Smokers who do not use SCA think to be able to quit or reduce smoking on their own. They do not perceive smoking as a problem and therefore do not believe to need help. That heavy and light smokers do not differ in their agreement to these reasons reflects a high confidence of both groups in their ability to quit without help but may also reflect an underestimation of the problems associated with smoking cessation particularly in heavy smokers. Furthermore smokers do not think that SCA are helpful. There seems to be a discrepancy between the scientifically proven effectiveness of SCA [7, 8] and the individually perceived effectiveness in persons most in need of these aids, i.e., the smokers who failed in previous quit attempts. This is corroborated by a study showing that only 20% of smokers are convinced that SCA increase their chances in quitting [28]. In addition to these reasons, one important environmental barrier could be found. For a quarter of all smokers, the costs of SCA are a reason for non-use. The costs for e.g. nicotine replacement therapy are calculated not to extend the costs for an equivalent amount of cigarettes smoked before. But smokers may consider only the additional costs for SCA compared with no costs for quitting on one's own.

Although the most important reasons for non-use are the same in heavy and light smokers, there are differences between these groups. The expected costs as well as the belief that nothing would help in the attempt to quit or reduce are more relevant for heavy smokers. Furthermore the (social) aspects that using SCA means admitting to need help and the fear of embarrassment deter heavy smokers more strongly from SCA use than light smokers. So the belief that smoking cessation is something which has to be done on one's own seems to be more important for heavy smokers. This has to be kept in mind particularly when planning interventions for heavy smokers.

In interpreting these findings, the climate according to tobacco prevention and control must be taken into account. Germany is a country with low anti-smoking climate [29] and relatively high smoking prevalence, and the pressure to quit smoking is small. Smoking is widely accepted in the German society, which is reflected in a lower number of quit attempts and a lower motivation to quit than in the US [4, 5] or other European countries [6, 29]. Thus, fewer smokers have the experience of withdrawal symptoms and other problems impeding smoking cessation. Furthermore, in contrast to other countries such as the UK [30] and partly the US [31], in Germany costs for nicotine replacement therapy and bupropion are not covered by health insurance. Smoking cessation courses also require co-payments. This might explain why costs of SCA are given as a reason for non-use. It might also reflect that nicotine dependence is not sufficiently accepted by society as a disease for which free help should be offered. Our finding that 25 % do not use SCA because they do not want to admit needing help to themselves might reflect this feeling that smoking cessation should be done on one's own. These specific circumstances in Germany may compromise the generalisability of our findings across countries, because different smoking climates may influence the reasons for not using SCA.

Our findings suggest that interventions and campaigns aiming to increase the use of SCA, particularly in heavy smokers, and thus increase the number of successful quit attempts should address the following issues: First, if smokers are provided with fewer opportunities to smoke, the smokers' perception of their competences to quit smoking on their own might be adjusted. In this regard, smoking bans in public buildings or workplaces can be helpful. Second, higher perceived effectiveness of SCA is associated with more frequent use [28, 32]. Public education campaigns should address this issue. One aspect in such campaigns might be that smokers as well as health care providers should be aware that SCA are no stand-alone solution. SCA assist in smoking cessation but require motivation to quit and behavioural efforts as prerequisites. Heavy smokers in particular refrain from using SCA because of the perceived ineffectiveness. This makes it even more important to clarify that the available SCA are effective in particular for heavy smokers. Third, costs are a barrier of SCA use. Studies have shown financial coverage of SCA to be associated with increased use, quit attempts, and successful quitting [33–35]. This implies that reducing the costs of SCA might have a positive effect on the use of SCA.

We found that smokers intending to quit smoking within the next six months showed stronger agreement to both subscales ("Social and environmental barriers" and "SCA unnecessary") than smokers not intending to quit. One interpretation might be that this reflects greater cognitive involvement of smokers who are further along in the cessation process. Those smokers have already made up their mind and decided not to use any kind of help. Therefore, their reasons for not using SCA are more elaborated. These results highlight the necessity to address SCA already in smokers who are not motivated to quit, before they have consolidated how they want to quit. This is in line with other studies which confirm that SCA should be offered to all smokers irrespective of their motivation to quit [36, 37]. In heavy smokers the intention to quit was only related to the subscale "SCA unnecessary". This suggests that in heavy smokers not intending to quit the offer of SCA should be accompanied by a brief counselling to emphasise that smoking more cigarettes per day hampers smoking cessation [13] and that thus especially heavy smokers can profit from SCA such as nicotine replacement therapy [14]. Social and environmental barriers seem to be especially important for people with a lower educational level. This finding also stays significant when focussing exclusively on heavy smokers. Knowing that the use of SCA is more likely among people with higher education [12], additionally focussing on social aspects (e.g. talking to others) or environmental barriers (e.g. providing information about costs and places to turn to in order to get help) might be promising to increase the use of SCA in heavy smokers with lower education.

Our study has some limitations: (1) We assessed the reasons for non-use retrospectively in participants who unsuccessfully attempted to quit or reduce smoking. Thus cognitive processing resulting from the failure of the quit or reduction attempt and limited recall might have influenced our results. For example, participants who attempted and failed to quit might be likely to retrospectively report that SCA were unnecessary. Future studies should therefore assess reasons for non-use close to a given quit attempt, before the success or failure is obvious. (2) Our rationale was to focus on smokers reporting a quit or reduction attempt within the last 12 months. This constraint is founded in the wording of the questionnaire. Asking smokers why they have not utilised any SCA when trying to stop or reduce smoking assumes that they have had at least one opportunity to use any. Furthermore, assessing reasons related to an actual behaviour may be able to obtain more elaborated cognition. However, this means that our sample excluded smokers without a quit or reduction attempt. Therefore we were not able to investigate if and how general attitudes towards SCA influence whether a smoker tries to quit or reduce smoking. Future studies should therefore investigate whether those attitudes influence subsequent quit attempts. (3) We assessed reasons for non-use across a combination of all kinds of SCA. Reasons for non-use may differ between different kinds of SCA. For example, expenditure of time and money may vary between different SCA, which in turn may influence perceived reasons for non-use. In our study, we decided to assess the reasons for non-use globally for all kinds of SCA combined but not for single SCA, because in Germany information about SCA and the public awareness of the different kinds of SCA are low. Only 19% of current smokers have ever used SCA, with 2.8% reporting use of multiple SCA [11]. Thus differentiating reasons for non-use between SCA was not appropriate. (4) We adapted a questionnaire from alcohol dependence and misuse research to smoking cessation research. Although we added four smoking specific items, the reasons for non-use in the field of tobacco smoking might not have been covered completely. Psychometric development of a questionnaire with specific tobacco items is clearly desirable, but remains a task for future research. (5) Generalisation of our findings might be limited because our sample consisted of persons from two smoking cessation studies in Western Pomerania. However, both studies used population recruitment approaches, which assure the inclusion of a wide variety of smoking patterns, e.g. smokers not intending to quit within the next months. Because attrition was associated with educational level (population-based sample) and age as well as educational level (general practice patient sample), our findings might not apply to younger persons with a low educational level.

Our findings suggest that the main reasons for non-use of SCA are being overly self-confident and the perception that SCA are not helpful. These reasons are modifiable in nature and thus indicate potential targets for future interventions to increase the use of SCA.