Integration of the Theory of Planned Behavior and Transtheoretical Model of Change for Prediction of Intentions to Reduce or Stop Alcohol Use among Thai Adolescents.

BACKGROUND Alcohol use among Thai adolescents has been increasing over the past few decades, and efforts to control consumption by underaged youth have proven largely ineffective. Objectives: This study tested components of the Theory of Planned Behavior (TPB) and Readiness to Change, based on the Transtheoretical Model (TTM), to identify useful constructs for developing alcohol use interventions for youth. Methods: A sample of 825 Thai student drinkers (65% female), between the ages of 14 and 19, were recruited in Bangkok, Thailand. Hierarchical regression analyses were used to test components of the TPB and Readiness to Change as predictors of intention to reduce/stop alcohol use while controlling for age, gender and alcohol use. Results: The model accounted for 58% of the variance of intentions. The TPB components accounted for a significant increase in variance beyond that explained by age, gender and alcohol use, ΔR2 = .23, p < .001; Perceived Behavioral Control (PBC) was the strongest predictor (β =.41, p < .001), followed by Attitudes (β=.13, p < .001), and Subjective Norms (β =.09, p = .002). Readiness to Change composite scores (β=.54, p < .001) were added last and accounted for a further significant increase, ΔR2 = .24, p < .001. Conclusions: The findings suggest that interventions should assess Readiness to Change and utilize effective processes in facilitating change at each stage. Other suggestions are to improve participants' PBC and to further examine the role of specific social norms and attitudes regarding perceived benefits and disadvantages of alcohol use.