District programme to reduce smoking: can sustained intervention by general practitioners affect prevalence?

A total of 101 general practitioners in 27 practices in inner London took part in a quasi-experimental study designed to examine whether a brief intervention applied to all smokers seen by general practitioners and sustained on a continuous basis could in time have a cumulative effect and reduce the prevalence of smoking among their patients. Of 21 practices approached in our local district (Camberwell), seven were willing to undertake brief intervention with support from the smokers' clinic (SBI), four opted for intervention without support (BI), and six acted as usual care controls. A further 10 out of 12 practices approached in South Hammersmith provided an unselected group of usual care controls. A series of six cross-sectional surveys were conducted over a three-year period. Each survey consisted of all adult patients attending to see a doctor during a defined two-week period, sample sizes averaging just over 9000 per survey. The estimated decline in self-reported smoking prevalence over the 30-month period following the start of intervention was 5.5% (from 36.4% to 30.9%) in the SBI group compared with 2.1% for BI and 2.8% and 3.0% in the two usual care control groups, the decline in the SBI group being significantly greater than in the other groups which did not differ significantly between each other. These interim results provide encouraging evidence that brief intervention by general practitioners with support and back-up from a local smokers' clinic can, when sustained on a continuous basis, reach sufficient smokers to reduce smoking prevalence in their practice populations. However, firm conclusions must await longer periods of observation now that the other Camberwell practices have adopted the SBI procedures.