<![CDATA[Background: Thalassemia remains a major public health burden in Indonesia, particularly among populations with a familial predisposition. Objective: This study aimed to assess the validity, reliability, sensitivity, and specificity of a thalassemia screening instrument compared with HbA2 examination (hemoglobin electrophoresis) for early detection of thalassemia carriers among adolescents from families with known thalassemia cases. Methods: This cross-sectional study was conducted in Banyumas District from Januari to June 2025 and included 64 adolescents aged 10–24 years with a family history of thalassemia. A screening prototype was developed and validated through field testing and comparison with HbA2 examination as the gold standard. Diagnostic accuracy was evaluated using sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Results: The screening model demonstrated a sensitivity of 87,8% and specificity of 78,2%, with PPV of 84% and NPV of 39%. The area under the ROC curve was approximately 0.89, indicating acceptable diagnostic performance. These results suggest that the model is suitable as an early screening tool in low-resource settings. Conclusion: This study developed and validated a thalassemia screening model suitable for adolescents with familial risk. The model demonstrated moderate diagnostic performance and has potential for integration into public health programs for early detection. Keywords: Thalassemia; screening; adolescents; diagnostic test]]>
