Effective patient outreach is critical in preventive healthcare, particularly for managing high-risk populations susceptible to chronic conditions such as hypertension. This study evaluates the effectiveness of alternative communication strategies for improving the initial patient contact process at the Gimhae Public Health Center in South Korea. The current telephone-based outreach approach yields a low response rate (2%), underscoring the need for a more efficient engagement framework. Through a field experiment involving 480 high-risk individuals, we compare the effectiveness of two intervention strategies: (1) SMS notifications preceding phone calls and (2) customized health discussions tailored to patients' medical records. Empirical analysis reveals that SMS notifications significantly increase patient response rates, while customized health discussions increase the likelihood of patient follow-up visits. These findings provide evidence-based recommendations for optimizing patient engagement strategies in public health settings, demonstrating the value of targeted communication interventions in chronic disease prevention. The study contributes to the broader discourse on service design in healthcare by presenting a scalable framework for improving patient outreach in public health institutions.