Effects of educational interventions based on the theory of planned behavior on oral cancer-related knowledge and tobacco smoking in adults: a cluster randomized controlled trial

The theory of planned behavior (TPB) is an effective model for facilitating behavioral change. The aim of the present study was to evaluate the impact of TPB-based educational interventions on oral cancer-related knowledge and tobacco smoking behavior in an Iranian adult population in 2022. In this randomized controlled trial, a total of 400 healthy individuals were enrolled. The study was implemented in 20 urban health centers in the south of Tehran, Iran. The health centers were randomly allocated into two intervention groups. In group PowerPoint (PP), the participants received education through a 20-minute PowerPoint presentation complemented by a pamphlet. Group WhatsApp (WA) was educated via WhatsApp messages and images. Data was collected using a structured questionnaire at baseline, and at one- and three-month follow-ups. The outcomes were evaluated in terms of knowledge, tobacco smoking behavior, and the related model constructs i.e. intention, attitude, subjective norm, and perceived behavioral control. Generalized estimating equations (GEE) regression models were applied to assess the effect of interventions on repeated measurements of the outcomes. All analyses were conducted using STATA Software Version 17. Out of all the participants, 249 (62%) were women. The mean and standard deviation (SD) of age were 39.67 and 13.80 years. Overall, group PP had a significantly higher score of knowledge compared to group WA (β = 0.43, p = 0.005). No significant differences were found between the groups with regard to tobacco smoking and the related TPB constructs, except for attitude with a higher score in group PP compared to group WA (β = 0.50, p = 0.004). At the three-month follow-up, both interventions had significant effects on increasing knowledge (β = 4.41), decreasing tobacco smoking (OR = 0.54), and increasing intention (β = 1.11), attitude (β = 1.22), subjective norm (β = 1.37), and perceived behavioral control (β = 1.08) (P