This study aimed to explore the factors predicting the intention to quit smoking and the subsequent behavior 6 months later using the theory of planned behavior (TPB). Data were obtained from 145 smokers who attended a smoking cessation clinic in a community hospital. All participants completed a questionnaire which included demographic information, TPB-based items, perceived susceptibility and previous attempts to quit. The actual quitting behavior was obtained by follow-up phone calls 6 months later. The TPB constructs explained 34% of the variance in intention to quit smoking. By adding perceived susceptibility, the explained variance was significantly improved to 40%. The most important predictors were perceived behavior control and perceived susceptibility, followed by attitude. Subjective norm did not contribute to the prediction of intention. Attitude and perceived behavior control contributed to the prediction of actual quitting behavior, but intention, subjective norm and perceived susceptibility did not. Our findings support that the TPB is generally a useful framework to predict the intention to quit smoking in Taiwan. The inclusion of perceived susceptibility improved the prediction of intention. With regards to successfully quitting, attitude and perceived behavior control played more crucial roles than other TPB constructs. Smoking cessation promotion initiatives focusing on reinforcing cessation belief, enhancing a smoker's perception of their capability to quit smoking, and persuading smokers that they can overcome cessation barriers to cessation could make subsequent interventions more effective.
Keywords: Theory of planned behavior; intention; perceived behavior control; quitting behavior; smoking cessation.