Beyond Average Effects: Heterogeneous Impacts of Health Checkup and Behavioral Guidance on Health Care

There exists a globally growing concern regarding the prevention and control of noncommunicable diseases (NCDs), and Japan is no exception, as lifestyle-related NCDs have a significant impact on public health. To prevent the prevalence of metabolic syndrome and control rising healthcare costs, the Japanese government initiated a novel annual health checkup program in April 2008. We examine how organized prevention programs affect healthcare outcomes, separately identifying screening effects versus behavioral intervention effects while documenting substantial heterogeneity across demographic subgroups. Using comprehensive administrative data from Japan’s National Health Insurance system (FY 2011–2016), we employ instrumental variable estimation exploiting peer participation rates to address selection bias in voluntary health checkups, and difference-in-differences estimation leveraging systematic assignment rules for behavioral guidance interventions. Health checkup participation generates minimal average effects but substantial heterogeneity: younger participants (40–64 years) reduce hospitalization, while elderly participants (65–74 years) increase outpatient care expenditures. Males experience higher inpatient care costs; females significantly reduce hospitalization. Income-based heterogeneity is absent, suggesting Japan’s universal coverage successfully minimizes financial barriers. Strikingly, light-touch motivational support proves more effective than intensive sixmonth guidance at increasing outpatient care utilization, with effects concentrated among elderly, female, and lower-income populations. These findings reveal fundamental misalignment in current program design: resource-intensive interventions target populations least responsive to behavioral guidance while the most responsive populations receive minimal support. Our results challenge conventional dose-response assumptions and have important implications for optimal prevention program design in aging societies worldwide, suggesting substantial efficiency gains through reallocation toward targeted light-touch interventions.