Smoking cigarettes remains the single most preventable cause of death in the United States. According to the Centers for Disease Control and Prevention, smoking is responsible for approximately 440,000 premature deaths annually, at an estimated cost of $157 billion in health-related economic losses per year. Smoking accounts for nearly one-third of all annual cancer deaths and also increases risk of coronary heart disease , stroke , emphysema , and bronchitis .

Although the prevalence of smoking has dropped dramatically over the past 50 years, more than 22% of the U.S. population (46 million people) still smokes. This is no doubt partly because nicotine in so addictive. Public health officials and primary care physicians have long been struggling to help people quit through a variety of interventions. In addition to group and individual counseling, several medications have been approved to help people quit: these include nicotine replacement products and the antidepressant drug, bupropion (Zyban).

In order to assess just how effective typical smoking cessation interventions can be, and to demonstrate the degree of health benefit they may offer, researchers supported by the National Heart, Lung, and Blood Institute (NHLBI) conducted the most rigorous study yet on the impact of a smoking cessation intervention. Findings from the final phase of this multi-phase study, the Lung Health Study (LHS), published in the February 15, 2005 issue of the Annals of Internal Medicine , suggest that cessation programs can significantly lower mortality rates measured up to 14.5 years down the line.

About the Study

From 1986-1988, the LHS enrolled 5887 smokers aged 35 to 60 from 10 clinical centers in the U.S. To be eligible, the smokers had to have evidence of mild to moderate airway obstruction while at the same time not considering themselves ill. Anyone with existing lung or other serious disease, high blood pressure, obesity, or excessive alcohol intake was excluded. On average, participants were white, heavy smokers (averaging 31 cigarettes a day) with some post-secondary education. The smokers were randomly assigned to one of two treatment groups:

  • Intervention: A 10-week smoking cessation program comprised of a strong physician message and 12, two-hour group sessions using behavior modification and nicotine gum, plus either ipratropium (a bronchodilator) or a placebo inhaler
  • Non-intervention: “Usual care,” i.e. no care, in this case

Intervention participants who successfully quit were also entered into a maintenance program that stressed coping skills.

For the final phase of this study, the researchers compared short and longer-term mortality between the groups. They acquired this data for 98% of original participants by one of two means:

  • About 75% of participants were tracked for up to 14.5 years mostly by way of telephone; whenever a death was reported, staff analyzed clinical data to ascertain the cause.
  • For most of the other 25% of participants, a National Death Index provided date and cause of death through the end of 2001.

The Findings

Measured after five years, the smoking cessation rate was significantly higher in the intervention group: 21.7% of intervention participants were sustained quitters as compared to only 5.4% of the usual care group. Despite this cessation rate difference, there was no five-year difference in morbidity or mortality among the treatment groups.

By the end of the study (up to 14.5 years of follow-up), 731 deaths had occurred among all participants (12% of initial enrollees). Lung cancer was the most common cause of death (33%), followed by cardiovascular disease including coronary heart disease (22%).

By this time, mortality rates did differ between treatment groups: smokers who received the cessation intervention were 18% less likely to have died than those in the non-intervention group. And, when analyzed by smoking status (i.e. sustained quitter, intermittent quitter, or continuing smoker)—regardless of whether or not participants had received the cessation program or not, an increased risk of death for continuing smokers was even more apparent.

Other interesting LHS findings include:

  • The youngest intervention recipients experienced the greatest degree of risk reduction.
  • Smokers who smoked more than 40 cigarettes a day had a significantly higher death rate than those who smoked 39 or fewer.
  • Over 90% of the participants who quit within the first five years of the study were able to maintain cessation until the end of the study follow-up.
  • Male and female mortality rates were not significantly different.

How Does This Affect You?

In the end, the intervention helped smokers quit, and quitting improved ex-smokers longevity. And even though it was only successful in a minority of participants, the intervention substantially reduced mortality rates within fifteen years’ time. It is important to realize, however, that everyone in the study had some smoking-related lung disease at the time the study began. There is no guarantee that the results will apply equally to smokers with completely normal lungs.

Owing to the LHS’ large size and lengthy follow-up, these results should help remove any remaining doubt about the long-term value of smoking cessation programs. By demonstrating that one such program can and did affect long-term health outcomes at the population level, the LHS suggests that smoking cessation is probably both effective and economical. The authors of this study estimate that a unit price of $2000 would cover the costs of the LHS intervention—an amount that is clearly worth the program’s life-saving capabilities.

In addition, given the decrease in mortality among quitters after fifteen years but not after only five, the LHS adds to existing research indicating that the benefits of quitting smoking may take some time to fully surface. In previous studies it has taken three years after quitting for heart disease risk to drop to the level of never-smokers. The LHS study clearly shows that quitting also reduces the risk of lung cancer, though only after a lag period of about five years.

Finally, it is encouraging to see that many of the participants in this study who quit were able to stay quit permanently. The proportion of permanent quitters versus “intermittent quitters” was significantly higher among those who received the special smoking cessation intervention. So, if you are a smoker or know someone who is, you can be all the more confident in deciding to commit to a smoking cessation program or suggesting one to someone else.