Effectiveness of two educational interventions based on the theory of planned behavior on oral cancer self-examination in adults: a randomized controlled trial

Background The theory of planned behavior (TPB) is recognized as an effective theory for behavior change. The aim of the present study was to investigate the impact of two TPB-based educational interventions on oral self-examination (OSE) behavior and the related TPB constructs among adults in Tehran, Iran, in 2022. Methods This randomized controlled trial involved 400 healthy individuals recruited from 20 urban comprehensive health centers in the southern part of Tehran, Iran. The health centers were randomly assigned to two control (PowerPoint) and intervention (WhatsApp) groups (200 individuals in each group). In the control group (the recipient of the routine care), participants received a 20-minute lecture through a PowerPoint presentation and a pamphlet. In the intervention group (the recipient of an additional intervention alongside the routine care), participants were educated through messages and images on WhatsApp along with having monthly group discussions. Data was collected at baseline, as well as at 1- and 3-month follow-ups using a structured questionnaire. The outcomes assessed included OSE behavior and the related TPB constructs: intention, attitude, subjective norm, and perceived behavioral control. Linear and logistic generalized estimating equations (GEE) regression models were used to evaluate the impact of the interventions with STATA version 17. Results Of the total participants, 151 (37.75%) were men. The mean +/- standard deviation (SD) of ages in the PowerPoint and WhatsApp groups were 39.89 +/- 13.72 and 39.45 +/- 13.90, respectively. OSE and the related TPB constructs showed significant differences between the groups at the 1-month post-intervention assessment. The effect of PowerPoint was more significant in the short-term (one month), while both methods showed similar effectiveness after three months, specifically in relation to OSE and the TPB constructs. At the 3-month post-intervention assessment, there were significant increases in OSE (OR = 28.63), intention (beta = 1.47), attitude (beta = 0.66), subjective norm (beta = 2.82), and perceived behavioral control (beta = 1.19) in both groups (p < 0.001). Conclusions The present study provides evidence of the effectiveness of both educational interventions in improving OSE and the TPB constructs after three months. Therefore, both TPB-based educational methods can be recommended for designing and implementing interventions aimed at preventing oral cancer.