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PRIORITY PRESS - Canadian Cardiovascular Congress 2010

Montreal, Quebec / October 23-27, 2010

No intervention has a greater impact on lowering the risk of cardiovascular (CV) events than smoking cessation. In primary or secondary prevention, the relative risk reduction from smoking cessation exceeds that achieved by blood pressure control or lipid lowering, is generally observed more rapidly, and yields progressively greater protection over time. Although smoking cessation is often more challenging than treating hypercholesterolemia or hypertension, the greater gains warrant the effort.

Smoking as an Addiction, not a Habit

Rather than a lack of effective therapies, the barrier that prevents physicians from devoting the types of systematic and aggressive therapies to smoking cessation that are employed for other modifiable risk factors is a misunderstanding of the basic issue. “We need to get beyond the outdated concept that smoking is a habit,” stated one of the co-chairs of the committee that assembled the CCS position statement, Dr. Andrew L. Pipe, University of Ottawa Heart Institute, Ontario. He indicated that many health care professionals, including CV specialists, maintain the view that smoking represents a choice and not quitting a lack of willpower. Rather, it is an addiction that requires active treatment, typically with an approach that includes pharmacological agents.

Evidence for Pharmacotherapy

The critical importance of a systematic treatment is emphasized in the new CCS position statement and is evidence-based. While drug therapy cannot be prescribed as an isolated approach to smoking cessation, the guidelines name 3 therapies with proven efficacy. These are varenicline, nicotine replacement and bupropion. In his presentation, Dr. Pipe cited a meta-analysis of randomized trials by Dr. Mark J. Eisenberg, Division of Cardiology, McGill University, Montreal, Quebec, who co-chaired the Smoking Cessation Position Statement. Published in the Canadian Medical Association Journal in 2008 (Eisenberg et al. CMAJ 2008;179:135-44), the meta-analysis included 69 controlled trials with 32,908 randomized subjects. The odds ratio (OR) of success relative to placebo for the most effective therapies was 2.41 for varenicline, 2.07 for bupropion and 2.06 for the nicotine tablet.

In a hierarchical analysis, varenicline was “favoured” over the other pharmacotherapies, but Dr. Eisenberg and co-investigators cautioned that this type of analysis could not be considered definitive. However, in the 3 trials that directly compared varenicline to bupropion, which was the next most effective agent, the OR of success for varenicline over bupropion was 2.18 (95% CI, 1.09-4.08).

New data presented at the CCC also suggested that treatments for smoking cessation may not be interchangeable. In this pilot study presented by Dr. Pipe, 50 patients in hospital with an acute coronary syndrome (ACS) or scheduled for a percutaneous coronary intervention or a coronary artery bypass graft were randomized to varenicline or a transdermal nicotine patch. Both therapies were supplemented with regular nurse counselling before and after discharge.

On the primary end point of being smoke-free at 12 weeks, the rates were 45% for varenicline and 31.6% for the transdermal patch. Although the OR favouring varenicline (1.77; P=0.39) did not reach statistical significance, Dr. Pipe indicated that significant differences would be difficult to achieve in a study this small. Indeed, he was encouraged by the results.

“We feel these results represent a very important clinically significant difference in favour of varenicline therapy,” Dr. Pipe told delegates. He noted that the benefit of initiating therapy in patients hospitalized for coronary artery disease “is consistent with the benefit of varenicline in patients with stable coronary artery disease.” Although he underlined the limitations of a relatively small study with a modest length of follow-up, he remarked, “I think it is very significant that we can induce smoking cessation following 12 weeks of pharmacotherapy in 45% of our cardiac patients.”

Cumulative Benefit over Time

One potential advantage of varenicline observed in this and other studies is that it appears to offer more of a cumulative benefit over time than alternatives, according to Dr. Pipe. While smoking cessation typically occurs immediately or not at all with nicotine replacement or bupropion, smoking cessation accrues over time in patients treated with varenicline so that quit rates are still climbing after 2 or more months of therapy.

Whether this accrual of cessation success is a product of the mechanism of varenicline—which is a partial agonist of the a4ß2 subtype of the nicotine acetylcholine receptor and may produce a more durable suppression of nicotine craving—is unclear, but this pattern underscores the premise that smoking addiction is a treatable disorder.

Importance of a Systematic Approach

However, even with relatively effective pharmacotherapy, it is important to recognize that treatment of smoking cannot be limited to writing a prescription. Rather, the insidious nature of addiction demands a more comprehensive approach that will likely require some form of behaviour modification.

The need for counselling and behaviour modification may be another reason why physicians have not been aggressive at many centres in providing smoking treatment, but the 6 key recommendations of the position statement are designed to provide the structure for a systematic approach. Physicians need not bear the full burden of successful treatment, but they do need to know to identify smokers, refer smokers for treatment and follow smokers until the treatment goal has been achieved.

In outlining the position statement, Dr. Pipe said the first recommendation of the CCS is a systematic approach in all health care settings with which the smoker comes in contact. Once an organized and systematic approach has been developed, 3 of the 5 remaining recommendations regard management. These are to identify and document smoking status within standard health assessments, provide clear, concise, unambiguous and non-judgmental advice to smokers on their options for quitting, and to become familiar with the pharmacotherapies available to help individuals quit smoking. The other 2 recommendations in the CCS position statement address the importance of leadership and training for smoking cessation within medical education and the need to advocate for public policies to control use of tobacco products.

Revisiting the INTERHEART Data

The benefits of smoking cessation are well defined not only for the prevention of CV disease but also for a variety of other health risks, particularly cancer. In CV disease, a history of smoking in the INTERHEART study was associated with an OR of 2.87 for a CV event relative to a never-smoker, which far exceeded the 1.91 OR associated with a history of hypertension (Yusuf et al. Lancet 2004;364:937-52). While current smoking increases the risk over former smoking, the difference between former and never-smoking diminishes over time. The dose effect is enormous. In one study, the risk of an event increased by twofold for those smoking 6 or fewer cigarettes per day but rose to eightfold for those smoking 2 packs per day.

Dr. Pipe expressed dismay that the CCS had not previously issued a position statement on this issue, but the new statement benefits from research conducted over the past several years. In particular, this policy statement is supported by evidence-based treatment recommendations. Although pharmacotherapies must be offered to individuals demonstrating a motivation to quit, they are part of a strategy to help patients combat a serious addiction.

Summary

The CCS has issued its first position statement on smoking cessation. The statement attempts to emphasize that smoking is an addiction and not a habit. Smoking cessation is not usually achieved without intervention, typically with pharmacotherapies. Specialists and primary care physicians should participate in a systematic approach that includes both evaluation of smoking status in every patient and a treatment program in all those who continue to smoke. There is evidence-based support for intervention, and the risk reduction with effective smoking cessation is likely to exceed that provided by control of any other modifiable risk factor.