Thesis (Ph.D.)--Chulalongkorn University, 2013

This study was a correlational study aiming to examine the direct and indirect relationships of the predicting factors of quit attempt in Thai adolescent smokers. The conceptual framework was developed based on social cognitive theory (SCT) and research-literature review. Multi-stage random sampling was used to recruit the sample. They were 463 adolescent smokers in grades 7-12 from 12 schools that belonged to the Teacher’s Network against Tobacco (TNT) in all regions of Thailand and had attempted to quit smoking within the past three months. Subjects completed seven self-administered questionnaires. All questionnaires demonstrated acceptable content and construct validities, and reliability. Data were gathered from October to December 2013. The majority of the subjects were Buddhist (95.5%) and males (94.2%) that studied in grade 9 (28.5%). The average age was 15.20 years (SD=1.38). Most of them started smoking before 14 years of age (80.13%). Path analysis (LISREL 8.53) was used to test the relationships among variables. The findings revealed that the hypothesized model fit the empirical data and could explain 50% of the variance of the quit attempt (Chi-square=14.64, df=7, p=0.05, Chi-square/df=2.09, GIF=0.99, RMSEA=0.049, SRMR=0.05, AGFI=0.97). All independent variables had significant relationships with quit attempt at the .05 level. Time spent with peer smokers had a negative direct effect (ß= -.26) on quit attempt, and it had a negative indirect effect on quit attempt through self-efficacy to resist smoking (ß= -.25), and motivation to quit (ß= -.25). Self-efficacy to resist smoking had a positive direct effect (ß= .26) on quit attempt. Nicotine dependence had a negative direct effect (ß= -.30) on quit attempt, and it had a negative indirect effect (ß= -.23) on quit attempt through self-efficacy to resist smoking. Motivation to quit had a positive direct effect (ß=.24) on quit attempt. Surprisingly, intensity of smoking cessation intervention had negative direct effect on quit attempt (ß= -.02), and it had a positive indirect effect on the quit attempt through self-efficacy to resist smoking (ß= .04) and motivation to quit (ß= .02). These findings demonstrated that the highest impact factors influencing quit attempt was nicotine dependence, followed by time spent with peer smokers and self-efficacy to resist smoking. Identifying these variables can help tailor cessation programs to more effectively help adolescents quit smoking.