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Dear SocNet listmembers

An article published in the most recent New England Journal of Medicine confirms the effects of family and friends on smoking behaviour, and indicates that both smokers and non-smokers cluster. Although one of the conclusions of the article is that "smokers are increasingly marginalized socially", an accompanying editorial suggests this may be bad news in terms of promoting smoking cessation because isolated subgroups where smoking is the norm tend to reduce the likelihood of quitting of people in those subgroups.

Abstract is pasted below.

with regards
Iain Lang

The Collective Dynamics of Smoking in a Large Social Network
Nicholas A. Christakis, M.D., Ph.D., M.P.H., and James H. Fowler, Ph.D.


Background The prevalence of smoking has decreased substantially in the United States over the past 30 years. We examined the extent of the person-to-person spread of smoking behavior and the extent to which groups of widely connected people quit together.

Methods We studied a densely interconnected social network of 12,067 people assessed repeatedly from 1971 to 2003 as part of the Framingham Heart Study. We used network analytic methods and longitudinal statistical models.

Results Discernible clusters of smokers and nonsmokers were present in the network, and the clusters extended to three degrees of separation. Despite the decrease in smoking in the overall population, the size of the clusters of smokers remained the same across time, suggesting that whole groups of people were quitting in concert. Smokers were also progressively found in the periphery of the social network. Smoking cessation by a spouse decreased a person's chances of smoking by 67% (95% confidence interval [CI], 59 to 73). Smoking cessation by a sibling decreased the chances by 25% (95% CI, 14 to 35). Smoking cessation by a friend decreased the chances by 36% (95% CI, 12 to 55 ). Among persons working in small firms, smoking cessation by a coworker decreased the chances by 34% (95% CI, 5 to 56). Friends with more education influenced one another more than those with less education. These effects were not seen among neighbors in the immediate geographic area.

Conclusions Network phenomena appear to be relevant to smoking cessation. Smoking behavior spreads through close and distant social ties, groups of interconnected people stop smoking in concert, and smokers are increasingly marginalized socially. These findings have implications for clinical and public health interventions to reduce and prevent smoking.

Dr Iain Lang
Epidemiology & Public Health Group
Peninsula Medical School
Exeter EX2 5DW, UK.
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