Impacts of Primary Care Physician System on Healthcare Utilization and Antibiotic Prescription: Difference-in-Differences and Causal Mediation Analyses.

Abstract

The overutilization of healthcare and overuse/misuse of antibiotics in Japan are responsible for the increase in healthcare expenditure and the development of antimicrobial resistance. The Japanese government started paying incentives to medical facilities for primary care physician registrations, but the impact of this new policy is still unclear. We conducted a retrospective cohort study for all pediatric outpatients from April 2015 to December 2016 in Japan, targeting 1.4 million children under 2 years of age. We investigated the effects of primary care physician registration on physician visits, total antibiotic use and admission rates using difference-in-differences (DID) and causal mediation analyses. DID analyses showed that primary care registration policy contributed to increases in total physician visits, total and broad-spectrum antibiotic use and radiologic study utilization, but reduced out-of-hour visits and did not affect hospitalization rates. Similar results were obtained when we adjusted for and matched on potential confounders. Causal mediation analyses found that the greatest pathway was controlled by direct effects of 53.2 DOTs per 1000 person-months (95% CI: 29.1-77.2), indicating that the effect of new health policy that did not mediate increased outpatient visits mostly contributed to the excess use of antibiotics. The health policy further increased antibiotic use. On April 2018, a new health policy of paying incentives for not prescribing antibiotics to children with respiratory infection or gastroenteritis was initiated. Further studies are needed whether this new health policy can mitigate the overutilization of healthcare and antibiotic use.