Effectiveness of a Web-Based Intervention for Preventing Substance Use in Young Adults in Taiwan: Quasi-Experimental Study

Background: Substance use has been one of the most alarming public health problems worldwide, particularly among younger generations. Objective: This study evaluated the effectiveness of a web-based substance use prevention intervention targeted at adults aged 20-29 years. Methods: The intervention materials comprised 5 sets of infographics and 1 animation, all of which focused on mixed themes: (1) the concept of substance use and its harmful effects on health; (2) misinformation regarding new psychoactive substances; (3) regulation of illicit drugs, particularly marijuana; (4) the brain disease model of addiction; (5) critical thinking skills that improve health literacy; and (6) decision-making and communication skills that help people refuse illegal drugs. The study assigned eligible participants into experimental and control groups on the basis of the parity of their participant numbers. These participants completed web-based baseline and follow-up questionnaires that assessed their knowledge, behavioral intention, self-efficacy, and life skills related to substance use prevention. Knowledge was assessed using 8 questions concerning understanding of substance use harms and the regulation of illicit drugs. Behavioral intention and self-efficacy were assessed using 5-point Likert-type scales. Participants’ ability to apply life skills to avoid substance use was assessed using 3 testing scenarios regarding substance use. The study used generalized estimating equations to examine the intervention’s effectiveness. Results: A total of 1065 participants (539 control and 526 experimental) completed the intervention and questionnaires in 2019. The average ages of the experimental and control groups were 25.68 (SD 2.71) and 25.66 (SD 2.69) years, respectively. The study observed no significant differences in the demographic variables between the 2 groups. The results of the generalized estimating equation analyses indicated that the intervention significantly improved participants’ knowledge (P<.001), behavioral intention (P<.001), and self-efficacy (P<.001) but not their life skills (P=.61) related to substance use prevention. Participants in the experimental group responded to a satisfaction survey with positive feedback on the intervention. Conclusions: The web-based intervention was effective in improving participants’ knowledge, behavioral intention, and self-efficacy concerning substance use prevention. The findings support continued efforts to use web-based interventions to prevent substance use among young adults.