Face to face advice for smoking cessation is effective,¹ but few smokers are willing to attend smoking cessation clinics, and many do not receive smoking cessation advice from their physician. Self help smoking cessation materials may not be very effective,² but computer technology can be used to produce effective individualised self help smoking cessation materials and disseminate them widely at a low cost per participant.² Most studies assessed the effect of computer tailored programmes on smoking cessation after one year or less.² Only one programme was evaluated during 18 and 24 months.³ These programmes usually produced quit rates<5% higher than in control groups who received standard self help materials or no intervention.² Because over one third of ex-smokers who achieve 12 months of abstinence eventually relapse five years later,⁴ it is not yet known whether computer tailored programmes have a long term impact on smoking abstinence.

We showed previously that a computer tailored programme doubled the odds of quitting smoking, after seven months.⁵ In this study, we tested whether this effect was maintained 24 months after entry in the programme—that is, 12 months after the end of the intervention.

METHODS

In 1998, we sent the baseline questionnaire to a representative (random) sample of 20 000 residents aged 18–60 in French speaking Switzerland. We sent out follow up questionnaires six and 23 months later to the 2934 baseline participants. We randomly assigned participants to the intervention or control group (fig 1).

The intervention consisted of personal counselling letters, written by a …