Effect of general practitioners' advice against smoking.

During four weeks all 2138 cigarette smokers attending the surgeries of 28 general practitioners (GPs) in five group practices in London were allocated to one of four groups: group 1 comprised non-intervention controls; group 2 comprised questionnaire-only controls; group 3 were advised by their GP to stop smoking; and group 4 were advised to stop smoking, given a leaflet to help them, and warned that they would be followed-up. Adequate data for follow-up were obtained from 1884 patients (88%) at one month and 1567 (73%) at one year. Changes in motivation and intention to stop smoking were evident immediately after advice was given. Of the people who stopped smoking, most did so because of the advice. This was achieved by motivating more people to try to stop smoking rather than increasing the success rate among those who did try. The effect was strongest during the first month but still evident over the next three months and was enhanced by the leaflet and warning about follow-up. An additional effect over the longer term was a lower relapse rate among those who stopped, but this was not enhanced by the leaflet and warning about follow-up. The proportions who stopped smoking during the first month and were still not smoking one year later were 0.3%, 1.6%, 3.3%, and 5.1% in the four groups respectively (P <0.001).The results suggest that any GP who adopts this simple routine could expect about 25 long-term successes yearly. If all GPs in the UK participated the yield would exceed half a million ex-smokers a year. This target could not be matched by increasing the present 50 or so special withdrawal clinics to 10 000.