Most cases of chronic obstructive pulmonary disease (COPD) are a direct result of tobacco smoking. Lung function decline stops if patients with early COPD stop smoking. Therefore, smoking cessation has become an integral part of the care of patients who use tobacco. Even minimal interventions have been shown to have an effect on smoking cessation rates. Unfortunately, only a small percentage of smokers quit for at least one year. A recent study of population spirometric screening found that 30 percent of smokers age 40 years and older with a history of tobacco exposure greater than 10 pack-years had airflow limitations. A preliminary study found that smokers who learned during spirometric screening that they had airflow limitation had a substantially higher cessation rate than those who appeared to have normal lung function. Górecka and associates studied the question of whether the diagnosis of airflow limitation combined with smoking cessation advice would influence cessation rates. They also attempted to identify predictors of successful outcomes.

The trial design was a prospective, comparative study in a university hospital outpatient clinic. Free spirometry testing was offered to all persons in the community who were 40 years and older and had a smoking history of 10 pack-years or more. Participants completed a questionnaire about their nicotine dependence and received standard spirometry tests. Results were provided in a booklet to the participants, and a physician reviewed the information with them and explained the relationship between their smoking habits and their spirometric results. Participants were strongly advised to stop smoking and were given a booklet about the harmful effects of smoking. Participants with airflow limitation were advised to follow-up with their family physician. A one-year repeat spirometry test was performed, and non-smoking status was confirmed by exhaled carbon monoxide measurements. Patients who did not return for follow-up were considered to be smokers.

Of the 558 smokers in the original study who were invited for follow-up screening, 66 percent participated. All of the participants had tried to reduce their smoking. The number of cigarettes smoked per day was reduced at one year in patients with airflow limitation and those with normal lung function. The one-year smoking cessation rates were similar between the groups. Participants with moderate to severe airflow limitations had the highest cessation rates. Factors that had a positive impact on cessation rates included older age, later age at the onset of smoking, lower pack-year history, fewer cigarettes per day, and less lung function.

The authors conclude that all smokers, regardless of their lung function, tried to modify their habits as a result of spirometric screening for COPD combined with smoking cessation advice. The diagnosis of airflow limitation motivated some smokers to quit, particularly those with moderate to severe limitations. The predictors of successful quitting included older age, less tobacco exposure, and less lung function.