Although intervention communities often showed substantial awareness of their programme, this rarely led to higher quit rates. Similarly, increased knowledge of health risks, changes in attitudes to smoking, more quit attempts, and better environmental and social support for quitting were not accompanied by reductions in community smoking levels. In the best designed trials, light to moderate smokers did slightly better than heavy smokers (the US COMMIT study), and men did a little better than women (the Australian CART study), but overall smoking rates remained similar between intervention and control communities.
The failure of the largest and best conducted studies to detect an effect on prevalence of smoking is disappointing. A community approach will remain an important part of health promotion activities, but designers of future programmes will need to take account of this limited effect in determining the scale of projects and the resources devoted to them.
Since smoking behaviour is determined by social context, the best way to reduce the prevalence of smoking may be to use community-wide programmes which use multiple channels to provide reinforcement, support and norms for not smoking.
To assess the effectiveness of community interventions for reducing the prevalence of smoking.
We searched the Cochrane Tobacco Addiction Group specialised register, MEDLINE (1966-January 2006) and EMBASE (1980-January 2006) and reference lists of articles.
Controlled trials of community interventions for reducing smoking prevalence in adult smokers. The primary outcome was smoking behaviour.
Data were extracted by one person and checked by a second.
Thirty-seven studies were included, of which 17 included only one intervention and one comparison community. Only four studies used random assignment of communities to either the intervention or comparison group. The population size of the communities ranged from a few thousand to over 100,000 people. Change in smoking prevalence was measured using cross-sectional follow-up data in 21 studies. The estimated net decline ranged from -1.0% to +3.0% for men and women combined (11 studies). For women, the decline ranged from -0.2% to + 3.5% per year (n=11), and for men the decline ranged from -0.4% to +1.6% per year (n=12). Cigarette consumption and quit rates were only reported in a small number of studies. The two most rigorous studies showed limited evidence of an effect on prevalence. In the US COMMIT study there was no differential decline in prevalence between intervention and control communities, and there was no significant difference in the quit rates of heavier smokers who were the target intervention group. In the Australian CART study there was a significantly greater quit rate for men but not women.