Carotid Plaque Screening Trial in Smokers

Tobacco smoking is highly prevalent in Switzerland (31% of adults), and 50% of smokers die from a tobacco-related disease, mainly cardiovascular disease (CVD). The smoking prevalence makes the evaluation of new strategies for smoking cessation a crucial priority.

The presence of plaques of atherosclerosis ("cholesterol" deposits in the artery wall), as measured by carotid ultrasound, increases the risk of future CVD. The use of plaque screening to motivate patients to improve smoking cessation has received little attention. In one study, screening for atherosclerotic plaques increased the self-reported rates of smoking cessation, but without biochemical validation of cessation and these smokers had only low nicotine dependence. Moreover, no trial has examined the impact of plaque screening on the control of other cardiovascular risk factors.

We now propose a randomized controlled trial of carotid plaque screening in 530 regular smokers aged 40-70 years, recruited from the community, to measure the impact of plaque screening on smoking cessation(main outcome) and control of other cardiovascular risk factors (secondary outcomes) after 1-year follow-up. Secondary outcomes are low-density lipoprotein cholesterol, hemoglobin A1C (if diabetes), high-sensitivity C-reactive protein and blood pressure. Smokers will all receive advice for smoking cessation and, then, will be randomly assigned to either the intervention group (with plaque screening) or the control group (without plaque screening). Smokers with one or more carotid plaque will receive pictures of their own plaques with a standardized explanation. To ensure equal contact conditions, smokers not undergoing ultrasound or without plaque will receive a standardized explanation on the risks of tobacco smoking.

This study is innovative because plaque screening is a promising and increasingly used strategy to motivate patients to stop smoking and improve control of cardiovascular risk factors, but its effectiveness has been poorly studied. Successful completion of this project will provide a strong scientific basis for using this strategy for smoking cessation and control of cardiovascular risk factors. If testing is not an effective tool, such testing might represent an important waste of expenditure, and healthcare expenditures should be used for other strategies. Given the scope of the global illness burden due to CVD, the simplicity of the proposed test (ultrasound of carotids) and the smoking prevalence in Switzerland, the evaluation of new strategies for smoking cessation in long-term smokers and the primary prevention of CVD is an important public health priority.

Beyond the randomized 1-year study, we have extended the follow-up to 3 years and added abdominal aneurysm screening by ultrasound to the intervention group to assess the association between cardiovascular risk factors and the development of small abdominal aortic aneurysms.

Inclusion criteria

• Current daily smoker with more or equal to 10 cigarettes per day for at least 1 year
• Age between 40 and 70 years

Exclusion criteria

• Prevalent CVD at baseline, defined as a medical diagnosis or self-report of coronary heart disease, stroke or transient ischemic attack, peripheral arterial disease, carotid artery disease, congestive heart failure, or having a pacemaker.
• Unstable life-threatening or severe medical conditions (major arrhythmia, cancer,…)
• Current psychiatric disease
• Current substance abuse (cannabis, other drugs, alcohol abuse)
• Current use of pharmacological agent to quit smoking
• Current participation in another clinical trial
• Plan to move out of the French part of Switzerland in the following year
• Recent carotid ultrasound (< 1 year) to assess subclinical CVD
• Language barrier (not fluent with French)
• Potential difficulty to obtain good imaging of the carotid by ultrasound: past radiotherapy or major surgery of the neck