BETHESDA, Md--A smoking-cessation study involving 11 pairs of
communities and more than 20,000 smokers found a slight advantage
for intervention among light-to-moderate smokers but no statistically
significant difference among heavy smokers.
Sylvan B. Green, MD, senior investigator in the Clinical and Diagnostic
Trials Section of the NCI's Division of Cancer Prevention and
Control, said the mean quit rate for light-to-moderate smokers
was 30.6% in communities where intervention programs were conducted
and 27.5% in comparison communities. For heavy smokers, the rates
were 18.0% and 18.7%, respectively.
Speaking at a symposium on tobacco addiction sponsored by the
NCI and the American Society of Clinical Oncology (ASCO), Dr.
Green called the difference for light-to-moderate smokers "not
as large as many of us would have hoped for, but we believe that
it is real." He noted that the findings would be of public
health importance "if you could actually get an additional
3% of light-to-moderate smokers to quit and stay off."
Dr. Green termed the results for heavy smokers "disappointing,"
but noted that these were the smokers more likely to have problems
The Study Design
The 22 North American communities in the Community Intervention
Trial for Smoking Cessation (COMMIT) were cities of 50,000 to
250,000 population, matched by geographic location, size, and
sociodemographic factors, Dr. Green said. The matched communities
were randomly assigned either to conduct a set of community-based
intervention programs or to serve as a comparison community without
such additional programs.
The study began in 1988 with a baseline survey of the 22 communities
and the identification of cohorts of smokers--10,019 "heavy"
smokers (25 or more cigarettes a day) and 10,328 "light-to-moderate"
smokers--who were followed over time, Dr. Green said. Active intervention
to influence smokers to quit took place from 1989 through 1992,
with final outcome data collected in 1993.