Physicians have long believed that encouraging patients to stop smoking leads to better health and longer lives, but until recently, results from randomized trials had been unable to clearly link smoking with increased mortality. Anthonisen and colleagues examined 14.5-year mortality data from the randomized, multicenter Lung Health Study to determine the effect of a 10-week smoking cessation program on all-cause mortality.

The study population consisted of 5,887 middle-aged patients (35 to 60 years of age) with an average 40.47 pack-year smoking history who smoked an average of approximately 31 cigarettes daily. All participants initially received written information stating that smoking cessation would reduce their risk for obstructive pulmonary disease, cardiovascular disease, and respiratory tract cancer. Participants were then randomized to usual care or a smoking cessation program that consisted of 12 two-hour group sessions where participants learned behavior modification techniques and received nicotine gum. Participants in the latter group who stopped smoking were subsequently enrolled in separate sessions that stressed coping skills.

The majority of participants were contacted by telephone every six months to update smoking status and mortality data. They were classified into three groups based on their smoking status during the initial five years of the trial: (1) sustained quitters, who stopped smoking during the first year and did not resume smoking; (2) intermittent quitters, who reported smoking at some but not all of their contacts; and (3) continuing smokers, who reported smoking at all contacts. When telephone contact revealed that a participant had died, an independent review board reviewed death certificates, autopsy reports, and medical records to classify the cause of death. After 14.5 years of follow-up, mortality data was available on 98.3 percent of the participants.

At the end of the follow-up period, 21.7 percent of the intervention group participants were classified as sustained quitters compared with 5.4 percent of the usual care group. Of the original group of participants, 731 died. The most common cause of death was lung cancer (240 deaths). After five years, mortality was similar between the usual care and intervention groups. After 14.5 years, however, there was a statistically significant increased risk of death for usual care participants who were younger than 45 years at the time of enrollment (hazard ratio [HR] = 1.88, P = 0.001) or who originally smoked at least two packs of cigarettes daily (HR = 1.30, P = 0.03). Sustained quitters had lower mortality rates than intermittent quitters and continuing smokers.

The authors conclude that the smoking cessation intervention used in the Lung Health Study reduces long-term mortality compared with usual care, even though nearly four out of five participants in the intervention group continued to smoke.