Abstract
Despite the serious influence of problematic Internet use on mental health among Japanese adolescents, no randomized clinical trials have investigated universal school-based interventions for this potential health challenge. Therefore, this study aimed to assess the efficacy of a school-based educational program. This two-armed, parallel, cluster-based randomized clinical trial included 5312 students from 13 high schools situated in a mid-sized Japanese city. The students in the intervention arm received 10 weekly standardized sessions, including a combination of information provision and interactive sessions by schoolteachers. The students in the control group followed a standard school curriculum. A generalized estimating equation model was applied to assess the primary (Korean Scale for Internet Addiction [K-scale] score) and secondary (behavioral change status according to changes in the transtheoretical model smartphone addiction score and Internet usage time) outcomes two months after intervention completion. The intention-to-treat analysis included 2597 (97.2%) and 2504 (94.9%) students in the intervention and control groups, respectively. Nevertheless, a significant discrepancy emerged regarding the behavioral change status. Therefore, this school-based program did not improve the Internet or smartphone addiction scores among Japanese adolescents. Further studies are needed to develop appropriate interventions for adolescents.