Temporal stability of the theory of planned behavior: a prospective analysis of sugar consumption among Ugandan adolescents

– Purpose: This study addressed three questions: What is the power of the Theory of Planned Behavior (TPB) in predicting adolescents’ intended and self‐perceived consumption of non‐milk extrinsic sugars using a non‐intervention prospective approach? To what extent do the TPB constructs change across time following adolescents’ mere exposure to an oral health survey? Do changes in self‐perceived sugar consumption at follow‐up associate with changes in behavioral intention as predicted by the TPB? Method: A survey was conducted in Kampala (urban) and Lira (rural) and 1146 secondary school students completed questionnaires assessing the TPB at school (Time 1). A random sub‐sample of 415 students was selected from the original survey of which 372 students were examined clinically. After 3 months (Time 2), the questionnaire was administered a second time in the sub‐sample. All analyses are based on the number of students who participated on both survey occasions, n = 372. Results: Attitudes and perceived behavioral control predicted intended sugar consumption at Time 1 and Time 2, accounting for 58% (ΔR2 = 0.58) and 19% (ΔR2 = 0.19) of the variance, respectively. Time 1 intention provided significant prediction of Time 2 self‐perceived sugar consumption with ΔR2 = 0.5. Adolescents with high‐caries experience more than their counterparts with low, changed towards weaker intentions and less frequent sugar consumption across the survey period. Mean sugar consumption scores changed from 2.6 to 2.7 (ns), 3.1 to 2.6 (P