Smoking reduction intervention in a large population-based study. The Inter99 study

Background. Smoking reduction has been introduced as an alternative to smokers unable or unwilling to quit but has never been implemented in a population-based intervention. Methods. Two thousand four hundred eight daily smokers in all motivational stages were included in a randomised population-based intervention study, in Copenhagen, Denmark. Smokers, unwilling or unable to quit, were encouraged to reduce their tobacco consumption. Furthermore, smokers in the high-intensity intervention were offered participation in smoking reduction groups. Results. Twenty-three percent of those who attended both baseline and 1 year visit reported reduction by at least 5 g and 8% reported a halving or more. Halving of tobacco consumption was achieved significantly more often than in the background population, OR = 2.6 (1.6-4.4), even when assuming that non-participants had not reduced, OR = 1.7 (1.0-2.8). Reduction of at least 5 g doubled the probability of increased motivation to quit and a halving increased it more than four times. The reductions were not validated. Less than 2% attended the smoking reduction groups. Conclusion. The smoking reduction intervention was significant in self-reported reduction of tobacco consumption and subsequently increased motivation to quit. This may open new perspectives, with reduction as a first step towards cessation, a possible supplement to smoking cessation strategies.