Development of a mobile application for screening the risk of premarital sex among adolescents in Northern Thailand

BACKGROUND: Despite existing efforts, premarital sex among Thai adolescents remains a critical public health concern, exacerbated by nearly universal smartphone access and prolonged daily digital exposure. Traditional surveillance often fails to provide the real-time, private intervention needed in this digital era. This research and development (R&D) design aimed to develop a mobile application for screening the risk of premarital sex among adolescents in Northern Thailand. METHODS: This research and development (R&D) study was conducted in three phases: (1) identifying 14 significant factors affecting premarital sex through a comprehensive literature review, (2) developing a mobile application via the Line Official Account platform, and (3) evaluating its diagnostic efficacy using a cross-sectional design. The sample consisted of 773 students (Grades 10-12 and years 1-3 vocational certificate) in Phitsanulok Province, Northern Thailand, recruited through stratified random sampling. Data collection was performed through real-time, self-administered digital assessments within the application. Statistical analyses focused on screening accuracy, including sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and the Area Under the Curve (AUC) of the Receiver Operating Characteristic (ROC). RESULTS: The participants had a mean age of 16.5 years (SD = 1.29). The overall prevalence of premarital sexual experience was 31.3%. Premarital sexual experience was more prevalent among males (33.1%) than females (29.8%), indicating notable sex differences in adolescent risk behavior. The developed application demonstrated high diagnostic performance with a sensitivity of 86.4%, specificity of 70.0%, and an Area Under the Curve (AUC) of 87.9%. The Positive Predictive Value (PPV) and Negative Predictive Value (NPV) were 56.6% and 91.8%, respectively, indicating its effectiveness as a real-time screening tool for identifying at-risk adolescents. CONCLUSION: The 14-factor mobile application was successfully developed and validated, showing high sensitivity and accuracy in screening premarital sex risks among adolescents in Northern Thailand. This digital platform effectively bridges the gap in traditional surveillance by providing a private and real-time assessment tool. Consequently, it is recommended that schools and health providers utilize this application to facilitate early intervention and prevent the long-term consequences of risky sexual behavior.