Motivational interviewing is a type of nonconfrontational counseling that encourages people to make a behavior change. It's been used to treat a number of unwanted behaviors, including alcohol abuse and drug addiction. Lai and colleagues examined studies that used motivational interviewing to break smoking habits. Their analysis included 14 studies published between 1997 and 2008 and involving more than 10,000 smokers.

While the interventions of all 14 studies were based on principles of motivational interviewing, they varied in terms of approach. For example, most studies included face-to-face meetings but two utilized phone calls; some involved single sessions while others provided several. These variations are noted by the authors, who suggest that they're cause for interpreting the results of their review with caution.

Results showed that motivational interviewing was slightly more effective in increasing smoking cessation than usual care or brief advice. Providers of motivational interviewing varied across studies and included general practitioners, hospital physicians, nurses, counselors, and psychologists. Results were more favorable when motivational interviewing was provided in a general-practice setting or by general practitioners. The authors noted, however, that this may be because of the established relationship between an individual and the practice or general practitioner.

Studies differed in the number and length of sessions, which ranged from one to four and from 10 to 40 minutes, respectively. Results indicated that sessions lasting longer than 20 minutes were more successful than shorter sessions. Individuals received a range of one to seven follow-up calls, but no clear evidence indicated the optimal number of sessions or follow-up calls.