Background: Motivational interviewing is widely used to help people to stop smoking. It is a counselling style which helps people to explore and resolve their uncertainties about changing their behaviour. It tries to avoid an aggressive or confrontational approach and instead steer people towards choosing to change their behaviour, and encouraging their self belief. The aim of this review is to discover whether motivational interviewing helps more people to quit than brief advice or usual care, when used to help people to stop smoking.

Study characteristics: We searched for new studies to add to this review in August 2014 and found 14 new studies. Twenty-eight randomized or cluster-randomized controlled trials are now included in this review. Studies were included if participants were tobacco users; provided participants were not pregnant women or adolescents; if the intervention being tested was based on motivational interviewing principles; if the study included some kind of monitoring of the motivational interviewing intervention, such as staff training or a measure of the quality of counselling delivered, or both; if the control/comparison condition was brief advice or usual care; and if the study reported smoking abstinence at least six months after the start of the programme. Between them these studies recruited 16,803 tobacco users. Two of the studies recruited smokeless tobacco users, and the rest recruited cigarette smokers. The majority of studies provided motivational interviewing support face-to-face; however seven studies delivered the support by telephone only.

Key findings: Our review found that motivational interviewing appears to help more people to quit smoking than brief advice or usual care when provided by general practitioners and by trained counsellors. Motivational interviewing carried out by general practitioners appeared to be more successful than when carried out by nurses or counsellors. Shorter motivational interviewing sessions (less than 20 minutes per session) were more effective than longer ones. A single session of treatment appeared to be marginally more successful than multiple sessions, but both delivered successful outcomes. The evidence for the value of follow-up telephone support was unclear, and face-to-face counselling did not help more people to quit than telephone counselling. Both approaches were more successful than brief advice or usual care.

Quality of evidence: We have assessed the evidence presented in this review as of moderate quality. Our results should be interpreted with caution, due to variations in study characteristics and how the treatment was delivered. In a number of cases it was difficult to assess the quality of included studies due to a lack of reporting of study details. Finally there is some evidence that studies which did not find an effect of motivational interviewing were less likely to be published and therefore this may impact upon our results.