Please note: In 2003, the CTF updated its Grades of Recommendations to include an "I Recommendation" for situations where insufficient evidence exists to allow a recommendation to be made. (Formerly, these situations were captured under a "C Recommendation".) This change is not retroactive, and all "C Recommendations" made prior to 2003 have not been reevaluated in light of the new "I" recommendation grade. For a discussion of these recommendation grades, please link to the 2003 article in the Canadian Medical Association Journal here.
These recommendations were finalized by the Task Force in January 1994
Contents
The reduction of tobacco-caused disease is a highly desirable goal for physicians. In 1986 the Canadian Task Force on the Periodic Health Examination recommended counselling for smoking cessation (A Recommendation). This chapter provides an update of evidence on strategies to achieve smoking reduction, again focusing on physician interventions. Smoking among pregnant women is addressed in a separate chapter (see Chapter 3).
Smoking cessation assistance (including nicotine replacement therapy) has been shown to be effective and is recommended. Reducing the number of young people who start smoking is critical but has been less intensively studied. Counselling to prevent smoking initiation is recommended (B Recommendation). There is also evidence to support referrals to other programs after giving cessation advice but insufficient evidence to evaluate counselling to reduce environmental tobacco smoke (ETS). Given the magnitude of the problem, educational programs, counselling and healthy public policies are all vital.
Burden
of SufferingThe 1991 survey results from Statistics Canada<3> indicated for the first time that the number of regular female smokers was greater than the number of males. The historically higher prevalence of smoking among men is no longer evident. Among women the overall decline in prevalence has been slight from 28% in 1966 to 26% in 1991.
The 1986 Labour Force Survey found that smoking ranged from 18% among professional workers to over 40% among transportation workers and miners. Armed Forces personnel have also been identified as a high risk group; a 1992 study found 53% of junior navy personnel smoked.
By ethnic origin, the highest smoking rates in Canada are found among Canadian Native peoples (59% regular smokers in 1990). In addition to high smoking rates among Native children (51-71%), the high prevalence of use of smokeless tobacco has also been identified as a concern for Native children and other adolescents.
While data on exposure to environmental tobacco smoke (ETS) are limited, a 1991 survey found that 44% of the Canadian work force is exposed to second-hand smoke at work. Such exposure was inversely related to occupational status. Fifty-four percent of Canadian children live in households with at least one smoker, and they are twice as likely to be regular smokers as those who do not live with a smoker.<4>
Parental smoking is associated with smoking initiation by adolescents.<4> Exposure to smokers in the home may be the single most important factor in determining whether a teenager will smoke. Assistance which physicians provide for adult smokers to quit may have a powerful effect on children in the home.
It has been estimated that there were over 38,000 smoking-attributable deaths in 1989, or 20% of all the deaths in Canada.<8> This resulted in 271,497 potential years of life lost before 75 years of age. The decline in smoking prevalence has played a major role in the reduction of mortality from cardiovascular disease, as well as in projected declines in mortality from lung cancer and chronic obstructive pulmonary disease (COPD).
Tobacco is highly addictive.<12> Over 75% of adult smokers would like to stop and at least 60% have tried to quit at some time in their lives. Approximately one-third of smokers attempt to quit every year. About 20% reported quitting on the first attempt, while 50% succeeded after 6 tries.
In 1986, about 90% of successful quitters and 80% of unsuccessful quitters used individual methods of smoking cessation rather than organized programs; most of these smokers used a "cold turkey" approach. Research on self-help/minimal intervention strategies is ongoing.
ManeuverPhysicians can also refer patients to smoking cessation programs; an inventory of self-help and group programs has recently been published.<16> Health care professionals can also promote non-smoking through a range of consulting and advocacy activities in health care settings as well as through communities, school boards, worksites, governmental agencies, legislatures and the media.
Effectiveness
of PreventionA 4-year cohort study<20> of Peer Assisted Learning (PAL) in Calgary grade 6 students found that the program prevented or delayed smoking initiation in 15% of males (p<.05). Its efficacy with females was negligible and the effect on prevention of regular as opposed to experimental smoking was unclear.
The educational programs which seem to show maximal effectiveness are those which emphasize the positive aspects of being smoke-free and promote self-esteem.<21> However, researchers have questioned whether educational programs on their own will ever lead to dramatic reductions in smoking initiation.<22>
When 12 to 17 year old smokers in Nova Scotia<23> were asked who should teach them about the effects of smoking on health, the option chosen by 23% was their family doctor. Also, 19% claimed that they would quit if their doctor so advised them. Several authors have suggested that the physician is strategically placed to advise young people effectively (expert opinion).<24>
The potential benefits in terms of prevention of addiction, the burden of morbidity and mortality for smokers and the effectiveness of counselling with regards to cessation (see below), provide further justification for counselling to prevent smoking initiation among children.
Nicotine replacement therapy has been found to be useful in many studies. The best results with nicotine chewing gum have been obtained with multi-component programs which have included some counselling and ongoing follow-up and support. In a 1987 meta-analysis by Lam and colleagues,<26> nicotine gum was superior to placebo gum in specialized cessation clinics (1-year abstinence rates of 23% versus 13%). Although nicotine gum was similar to placebo gum in general medical practice (11.4 versus 11.7%), nicotine gum was superior to the no gum control group (9% versus 5%).
Transdermal nicotine patches have been shown to improve 1-year cessation rates by 5-13%, in randomized controlled trials in comparison with placebo patches.<27-29> For the 24-hr patch, systemic side effects and/or withdrawal symptoms were reported in 32% of patch users as opposed to 24% of placebo patch users.<30> Local skin problems were reported by 14-50% of patch users and 0-13% of placebo patch users. Trials involving the 16-hour patch also suggest they may have fewer systemic side effects and local skin problems.<28> A 1994 meta-analysis of randomized controlled trials of nicotine replacement therapies including gum, patches, inhalers and nasal spray, found an overall odds ratio for abstinence with the use of nicotine adjuvants of 1.71 (95% confidence interval (CI): 1.56-1.87).<31> In a second meta-analysis of randomized trials of gum and patches,<32> nicotine 2 mg chewing gum had an overall efficacy of 6% (95% CI: 4%-8%), greater in self-referred subjects (responding to advertisements or attending anti-smoking clinics) than in invited (general practice or hospital patients) subjects (11% versus 3%). Efficacy was found to depend on the extent of dependence on nicotine as assessed by a simple questionnaire – the Fagerstr ¨ om test). It was 16% (7-25%) in "high dependence" smokers, but in "low dependence" smokers there was no significant effect. The 4 mg gum was effective in about 1/3 of "high dependence" smokers and appeared to be the most effective form of replacement therapy for this group. The efficacy of the nicotine patch (9% (6-13%) overall) was less strongly related to nicotine dependence, perhaps because the patch cannot deliver a bolus of nicotine to satisfy craving. While comparable in efficacy to other replacement therapies, the patch offers greater convenience and minimal need for instruction in its use. Other adjuncts to cessation therapy are available, but have undergone less thorough evaluation.
An intensive specific referral to a group smoking cessation program (counselling, videotape with testimonials and telephone call 1 week after referral) has also been shown to increase participation by patients in such programs (from 0.006% for those offered general advice to 11% for the intervention group in a study of 1380 smokers).<33> The authors recommend a brief office-based intervention preceding referral since most patients will not attend a group program.
Efforts to increase physician counselling have had some success. In randomized controlled trials, training, office systems and staff support have been shown to change physician behaviour<34> and doubling of quit rates among patients of physicians who had received training versus "control physicians" has been reported.<35> However, some trials have shown no statistically significant effect on quit rates although training may have had a small beneficial effect.<34,36> A randomized trial involving family physicians from the Hamilton, Ontario area found that 4 additional follow-up visits did not significantly improve cessation rates at 1 year (12.5% versus 10.2%).
While improving the cessation counselling offered by physicians has had mixed results, the evidence in support of counselling is clear. There is good evidence, based on multiple randomized controlled trials, to support cessation counselling and nicotine replacement therapy. Cessation interventions vary considerably in their effectiveness and many of the adjuncts to cessation counselling require further evaluation.
Tobacco advertising and sponsorship make smoking appear acceptable and desirable. In countries where advertising has been banned or severely restricted, childhood smoking has declined.<40> In Canada, since the introduction of the Tobacco Products Control Act, overall consumption has declined by 17.1%. Smoking among youths aged 15-19 years has declined from 22.5% in 1986 to 16% in 1991.
There is strong evidence that the simplest approach to discouraging smoking initiation by adolescents is to keep the price out of reach. Investigators have found that price increases of the order of 10% lead to short-term reduction of teenage consumption by 14%.<41,42> Recent tobacco tax cuts, unfortunately may help to sustain the tobacco problem in Canada.
Other important strategies include reducing child access to tobacco through effective tobacco retailing restrictions,<43> and bans on smoking in public places. Physician activities as community leaders can have dramatic effects in this area.<44>
Recommendations
of OthersConclusions
and RecommendationsThere is fair evidence to support physicians also referring patients to other programs after offering cessation advice (B Recommendation).
There is fair evidence to support counselling to prevent smoking initiation for adolescents (B Recommendation). Educational programs have not been shown to significantly reduce tobacco initiation. Counselling by physicians has not been evaluated but given the burden of disease, the benefits of preventing addiction, the effectiveness of other smoking-related counselling and the support of expert opinion, all children and adolescents should be counselled on avoiding tobacco use.
There is insufficient evidence to evaluate counselling to reduce ETS exposure (C Recommendation) but it may be useful to combine such counselling with cessation advice, again based on the burden of suffering, the potential benefits of the intervention and the effectiveness of cessation advice.
Unanswered
Questions (Research Agenda)EvidenceThis review was initiated in March 1993 and recommendations were finalized by the Task Force in January 1994.
Acknowledgements
Link to Structured Abstract of this review
Link to Summary Table of this review
Link to Selected References list of this review
Reprinted in modified format by the Canadian
Task Force on Preventive Health Care
with permission.
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Original Copyright
© 1994 Minister of Supply and Services Canada.
Last modified March 27, 1998.
