The physicians adopted a non-directive approach, included the five 'A' (ask, advice, assess, assist and arrange), assessing the stage of readiness in quitting smoking, strengthening clients' motivation to quit smoking using the five 'R' (relevance, risks, rewards, roadblocks and repetition) approach, and providing advice to overcome psychological craving, psychological dependence and social-cultural factors associated with tobacco dependency. Each smoker takes more than 30 min to complete the intervention.

According to the smokers' level of nicotine dependency, disease history, cigarette consumption, prescription of drugs were provided, Nicotine Replacement Therapy, bupropion and varenicline.

Smokers received follow-up by a counselor at 1 week, 1, 3, 6 months and 1, 2 years using a detailed questionnaire by telephone interview. At each follow-up, we collected data, asked whether the smokers have any problem with drug use or other problems, provided problem-oriented suggestions or advice as appropriate, encouraged them to insist.

All the interventions above are include in this group

The physicians adopted a non-directive approach, included the five 'A' (ask, advice, assess, assist and arrange), assessing the stage of readiness in quitting smoking, strengthening clients' motivation to quit smoking using the five 'R' (relevance, risks, rewards, roadblocks and repetition) approach, and providing advice to overcome psychological craving, psychological dependence and social-cultural factors associated with tobacco dependency. Each smoker takes more than 30 min to complete the intervention.

The whole project will last for 10 years in total, from Oct.2008 to Dec.2018. During the running, each participant will be followed by telephone tracking, an expected average of 2 years.