Washington, Oct 13 - Personalised, proactive phone counselling centred on motivational interviewing can help teenagers quit smoking, recent studies suggest.

Arthur V. Peterson and colleagues at Fred Hutchinson Cancer Research Centre, Seattle, designed a trial to evaluate to what extent phone counselling could help teenagers quit the habit.

Researchers identified more than 2,000 smokers via classroom surveys of juniors in 50 high schools in Washington state.

In 25 of the high schools, after parental approval teen smokers received personalised smoking cessation counselling that combined motivational interviewing and cognitive behavioural skills training.

These included using the smoker's own words and values to increase the importance of quitting, anticipating and coping with stress and other triggers to smoke, and making plans for stopping.

The study included over 700 non-smokers to ensure that contacting students for participation in the trial would not reveal a participant's smoking status.

More than a year after the intervention, nearly 89 percent completed a follow-up survey in which 22 percent reported a six-month prolonged abstinence from smoking, compared to 18 percent among students in the no-intervention control arm.

There was also strong evidence that the intervention had made a difference for three months, one month and seven-day abstinence and for the length of time since the last cigarette.

These findings were published online in the Journal of the National Cancer Institute.