Hospitalizations for Ambulatory Care Sensitive Conditions in a Large City of Japan: a Descriptive Analysis Using Claims Data

Background Hospitalization for ambulatory care sensitive conditions (ACSCs) is an indicator of the quality of primary care in different health systems. In Japan, where patients can choose any healthcare facility with universal health coverage (UHC), data on these admissions are unknown. Objective To describe the current situation of ACSC admissions in a city of Japan. Design Retrospective observational study using claims data. Participants Beneficiaries aged 0–74 years of the National Health Insurance (NHI) program in a large city in the Greater Tokyo Area. We extracted ACSC admissions from all inpatient claims between April 2013 and March 2017. Main Measures We calculated age- and sex-specific annual ACSC admission rates for three categories: acute, chronic, and vaccine-preventable. We estimated the age-adjusted admission rates by ACSC category according to administrative districts and rate ratios using Poisson regression models. We also estimated medical expenditures and lengths of stay for ACSC admissions. Key Results Of 91,350 hospitalization episodes, we identified 7666 (8.4%) that were ACSC admissions. Males had higher annual ACSC admission rates than females ( p < 0.001), especially for chronic ACSCs. Admission rates were lowest in those aged 15–39 years and higher in the youngest (0–4 years) and oldest (70–74 years) age groups. Age-adjusted chronic ACSC admission rates were lower in a newly developed area (rate ratio [RR]: 0.79, 95% confidence interval [CI]: 0.71–0.87) and higher in a residential area (RR: 1.14, 95% CI: 1.04–1.24) than in the center of the city. Total medical expenditures for all ACSC admissions accounted for 5.8% of the total inpatient expenditures of NHI in the city. Conclusions ACSC admission rates in Japan were higher for males than for females and showed a U-shaped trend in terms of age, as in other countries with UHC, and deferred by region. This study provided possible factors to reduce ACSC admissions.