— Smokers who believe they can avoid fatal disease by slashing the number of cigarettes they smoke each day are sorely mistaken, according to a new study which suggests the only safe way to escape the risk is to quit.
Long-term research conducted among more than 50,000 Norwegians found that men who halved their daily consumption of cigarettes were as likely to die of cardiovascular disease, reduced blood flow to the heart or cancer as heavy smokers.
And, remarkably, it found that women who cut back were in fact more likely to die prematurely than their heavy-smoking counterparts.
"There is no evidence that heavy smokers who cut down their daily cigarette consumption by more than 50% reduce their risk of premature death significantly," says lead researcher Kjell Bjartveit of the National Health Screening Service in Oslo, Norway.
The researchers warned doctors: "It may give people false expectations to advise them that reduction in consumption is associated with reduction in harm."
The findings will add to concerns about the way tobacco companies are encouraging smokers to alter their habits rather than quit (see Insight: Big tobacco's new smokescreen).
The 20-year study involved around 25,000 men and 26,000 women who were aged 20 to 49 at the start of the investigation. The study involved general health screenings at various intervals and participants were quizzed about their smoking habits.
After initial screening and selection, participants underwent two further screenings, at intervals of between three and 10 years, making for an unusually long monitoring period of up to two decades.
Participants were classified as:
Quitters, who gave up between the first and second check
Moderate smokers, of one to 14 cigarettes per day
Reducers, who cut their consumption by more than half at the second check
Heavy smokers, who smoked at least 15 cigarettes per day
Among men, "reducers" had a slightly lower death rate from all causes, when compared with heavy smokers, over the first 15 years. But after that, the death rates were virtually the same.
Women "reducers" ran half the risk of fatal lung cancer compared with heavily smoking females but, when death from all causes was factored in, their risk of premature death was actually 11% higher.
However, those who changed from reducers to quitters during the study had a 50% lower risk of premature death than sustained heavy smokers.
Journal reference: Tobacco Control (vol 15, p 472)