What proportion of smokers become addicted?

Most people who become smokers initiate smoking before the age of 18. They generally try smoking as part of experimentation, after observing their peers and family smoking and viewing tobacco advertising. It is fairly natural, when cigarette smoking can be observed so widely, for a child to think, “I wonder what that is like?”. Most kids who try smoking are not considering or expecting that they may become addicted. But it may be worth educating young people on their risks of becoming addicted. To do so we have to be clear about what we mean by “addiction”.

Nowadays the words “dependence” and “addiction” are generally used interchangeably with the same meaning. When used in relation to substance or drug use, these words refer to a situation in which the drug has come to unreasonably control a person’s behavior. The central characteristic of most definitions of drug addiction is that the individual experiences an impaired ability to reduce or end their use of the drug. In the case of cigarette smoking that characteristic is most commonly expressed as long term daily smoking despite awareness of the likelihood of serious health effects, a desire to reduce or quit, and failed attempts to reduce or quit.

In order to more clearly define, diagnose and study nicotine dependence, various diagnostic criteria have been developed, such as those of the American Psychiatric Association (DSM-IV) or the World Health Organization (ICD-10). These typically describe a list of criteria and require individuals to meet a certain number of these to meet the diagnostic threshold for “nicotine dependence”. There are 7 main DSM-IV criteria, (including things like difficulty cutting down, continued use despite it causing problems, experience of withdrawal symptoms when reducing etc) and if a smoker meets at least 3 of these they are considered to be “nicotine dependent”. Of course there is a certain artificiality about this because most people consider that nicotine addiction exists on a continuum of severity, rather than being a categorical disorder that a person either does or does not have. But these diagnostic frameworks at least give us a way of identifying those who are clearly addicted.

Last year, Drs Eric Donny and Lisa Dierker published a paper (in the journal, “Drug and Alcohol Dependence”) that aimed to identify what proportion of smokers in the general population met strict DSM-IV criteria for nicotine dependence. Their study was based on direct interviews with a large, representative sample of non-institutionalized adults in the United States in 2001-2. From that sample they focused on the 8,213 who were daily smokers in the past year. This sample included people who smoked anything from 1 to over 40 cigarettes per day, and people who had smoked for less than one to over 50 years.

The study found, not surprisingly, that the greater the number of cigarettes per day the person smoked, the greater the chance that they would meet strict diagnostic criteria for having become nicotine dependent. Whereas under 50% of those who smoked 1-5 cigarettes per day met the criteria, over 80% of those who smoked over 30 cigarettes per day met the criteria.

Unexpectedly, however, the longer the person had smoked, the less likely they were to have become dependent, particularly if the person had started smoking over 50 years ago. This finding seems very odd, and may have more to do with memory for quit attempts or attitudes to smoking among older age cohorts.

Overall, over 60% of ever daily smokers met strict diagnostic criteria for having become nicotine dependent. But almost all smokers had experienced at least one symptom of nicotine dependence. For example, 97% of “dependent” smokers had experienced difficulty cutting down their cigarette consumption, as had 72% of “non-dependent” smokers. The authors acknowledged that the differences in dependence between these two groups may be more quantitative rather than qualitative. The authors also acknowledged that certain co-occurring factors appear to make it more likely that a smoker will bcome dependent. An example they provided was a history of major depression, which is associated with approximately 100% nicotine dependence among heavy smokers.

So we can tell young people that if they take up smoking, there is an over 90% chance that they will experience some symptoms of nicotine addiction, and over a 60% chance that they will go on to meet strict diagnostic criteria for becoming addicted to nicotine.

A pdf copy of the full paper by Drs Donny and Dierner can be accessed (near the bottom of the page) at:
http://www.tern.org/Publications.htm

Labels: addiction, cigarette, cigarette smoking, dependence, jonathan foulds, nicotine

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Extended treatment for some addicted smokers

The brand new US Public Health Service Guideline on the Treatment of Tobacco Use and Dependence was written after an extremely thorough review of all the randomized controlled smoking cessation trials in the literature with at least 6 months follow-up.

http://www.surgeongeneral.gov/tobacco/

The guideline was also written by a large group of experts on tobacco treatment and healthcare. That guideline stated:

“For some patients it may be appropriate to continue medication treatment for periods longer than is usually recommended. Although weaning should be encouraged for all patients using medications, continued use of such medications is clearly preferable to a return to smoking with respect to health consequences.” (p126).

So what is meant by extended or “long term” treatment for tobacco dependence?

Most pharmacological tobacco dependence treatments (e.g. bupropion/Zyban, nicotine patch, nicotine gum) last for 7-12 weeks. Most non-pharmacological treatment is even shorter, e.g. the number of counseling sessions reimbursed by Medicare is 4 (>10 minutes) and group treatment most commonly consists of 6 weekly sessions. So in the field of tobacco dependence treatment, any treatment lasting longer than 12 weeks is considered “long term”. So is there any evidence that treatment lasting longer than 12 weeks may be safe and effective?

Williams et al (1) randomized patients to 52 weeks of varenicline (Chantix) or placebo. They found that varenicline was safe for a year of treatment and produced significantly higher quit rates at one year than placebo.

Tonstad and colleagues (2) treated 1927 smokers with the typical 12 weeks of varenicline and the 1236 who were not smoking at 12 weeks were then randomized to a further 12 weeks of varenicline or placebo (double blind). The question was, “does longer term treatment with varenicline prevent relapse over the next 12 weeks? By week 24, 30% of those who had varenicline had smoked, compared with 50% of those who had placebo for the last 12 weeks. So longer term varenicline resulted in more people succeeding in quitting smoking. When the participants were followed up at 12 months (i.e. at least 6 months off-drug for everyone) there were still more non-smokers among those who had varenicline for 24 weeks as compared to those who had it for 12 weeks.

But the added effects of longer duration treatment do not just apply to varenicline, or even just pharmacotherapy. Hall and colleagues (2004) (3) randomized smokers to standard 12 weeks of counseling and 8 weeks of nicotine patches plus either another 9 months of counseling, or 12 months of nortriptyline (an antidepressant that helps people quit smoking) or 12 months of placebo. At the one year follow-up, those who had nortriptyline and counseling for a year had a quit rate of 50%, as compared with only 18% for those who had nortiptyline but only 12 weeks of counseling, 30% for those who had 12 weeks of counseling and placebo, and 42% for those who had a year of counseling and placebo. The authors concluded that, “Comprehensive extended treatments that combine drug and psychological interventions can produce consistent abstinence rates that are substantially higher than those in the literature.” But as can be seen from the numbers, it was primarily the extended counseling that contributed to the unusually high one-year quit rates.

This study by Hall and colleagues was one of the first to really adopt the “chronic disease” model for smoking cessation, and it is also the one study to achieve the highest one year quit rates (50%).

The reality is that most smokers are not seeking extended (i.e. over 12 weeks) counseling or extended pharmacotherapy as a way to stop smoking. And many will not need it. The point is that those patients who have made a choice that they are willing to do whatever is necessary to save their life and become healthier by stopping smoking, and who appear likely to benefit from it, should be provided with extended treatment that appears likely to increase their chances. When 12 weeks of treatment have not succeeded in controlling hypertension, diabetes or asthma, we don’t expect our doctors to say, “oh well, never mind, it didn’t work and I won’t try to help you any more.” The same should go for tobacco dependence treatment. And when a patient has had 12 weeks of treatment but still feels vulnerable to relapse then there is evidence to suggest that the extended treatment may help them to remain smoke-free. The evidence is certainly not clear enough to recommend this to all patients, but it is sufficient to support it as an option for some.

(1) Williams KE, Reeves KR, Billing CB Jr, Pennington AM, Gong J. A double-blind study evaluating the long-term safety of varenicline for smoking cessation. Curr Med Res Opin. 2007 Apr;23(4):793-801.

(2) Tonstad S, Tønnesen P, Hajek P, Williams KE, Billing CB, Reeves KR;Varenicline Phase 3 Study Group. Effect of maintenance therapy with varenicline on smoking cessation: a randomizedcontrolled trial. JAMA. 2006 Jul 5;296(1):64-71.

(3) Hall SM, Humfleet GL, Reus VI, Muñoz RF, Cullen J. Extended nortriptyline and psychological treatment for cigarette smoking. Am J Psychiatry. 2004 Nov;161(11):2100-7.

Note: Jonathan Foulds has done paid work for pharmaceutical companies (Novartis, GSK, Celtic Pharma and Pfizer). This has included advising on potential new medicines, training health professionals, advising on clinical trial design, discussing barriers to quitting and reviewing applications for research grants. His main funding sources are mentioned in a funding statement on the bio page.

Labels: cessation, cigarette smoking, dependence, extended, jonathan foulds

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Celebrate your independence from tobacco

Here in the United States, the 4th of July is the day Americans celebrate their independence from Great Britain. It was on this day in 1776 that the 12 colonies agreed on the text of the Declaration of Independence and the first copy was signed by John Hancock (President of the Congress). It is certainly appropriate to celebrate the birth of this great nation and I hope everyone in the U.S. (and Americans abroad) enjoys their barbeques and fireworks today.

However, I think it is also appropriate for all of you who have at one time been addicted to tobacco and managed to quit, to take a moment to celebrate your own independence on this day. Giving up smoking is no easy thing to do and many of you will have taken many attempts before finally succeeding.

There is also some irony in celebrating your independence from tobacco on the 4th, because in fact this great nation was partly built on the proceeds from tobacco farming. In 1609, John Rolfe arrived at the Jamestown Settlement in Virginia. He is credited as the first man to successfully raise tobacco for commercial use at Jamestown, having brought the preferred Nicotiana tabacum seeds with him from Bermuda. . Shortly after arriving, his first wife died, and he married Pocahontas, a daughter of Chief Powhatan. Rolfe made his fortune farming and exporting tobacco. In the 17th century the English government increased import taxes on tobacco by 4000 percent, (increasing dissatisfaction among colonists and moves towards independence). During its first century after independence, tobacco taxes accounted for a third of the internal revenue collected by the US government.

The need for cheap labor to drive the profitable tobacco industry was also a primary reason for the introduction of slavery in the south. At the time of the signing of the Declaration of Independence, almost 50% of the population of Virginia were African slaves, numbering almost half a million by 1860. So the first colony in America (Virginia), the introduction of slavery, and the opposition to British taxes were all largely based around the growth of the tobacco industry.

So here we are on 4th July 2007. Those who have achieved mental and financial independence from tobacco should give themselves a pat on the back for succeeding in freeing themselves from this most deadly addiction. For those readers who are still smoking, what better day to make your own personal declaration of independence?

Labels: declaration, dependence, independence, nicotine addiction cigarette smoking tobacco

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