Significantly reducing the number of cigarettes smoked did not appear to have any long-term benefit in terms of death risk compared to not cutting down at all, according to the report published in the December issue of the American Journal of Epidemiology.

In the current study, Dr. Nina S. Godtfredsen of Copenhagen University Hospital and colleagues assessed the cause of death for nearly 20,000 people over a 15-year period. The investigators compared heavy smokers (15 or more cigarettes a day) who reduced the number of cigarettes they smoked by at least half during the study but didn't quit, with smokers who did quit, as well as people who continued to be heavy smokers. The researchers also looked at consistent light smokers, who smoked 14 cigarettes or less daily.

Heavy smokers who cut their cigarette intake by half saw no reduction in deaths from any cause during the study period. Quitters, on the other hand, had a 35% lower risk of death from all causes than those who continued to smoke heavily, while light smokers' death risk was 25% lower.

And quitters cut their risk of death from tobacco-related cancer by 64%, while there was no significant difference in mortality from such cancers for those who reduced their tobacco intake.

The researchers also found no difference in respiratory disease or mortality from cardiovascular disease between people who reduced their smoking and those who continued to smoke heavily.

The authors note that the study is the first, to their knowledge, to investigate from a prospective point of view the question of whether reducing cigarette smoking can cut mortality risk.

(Source: American Journal Epidemiology December 10, 2002)