Japan’s health system implemented universal health insurance coverage in 1961 and is one of the most successful health systems in the world, despite having one of the highest life expectancies and the highest old-age dependency ratio among advanced economies . However, annual medical expenditures per capita are in-creasing year by year, from JPY267,000 (USD2427) in 2007 to nearly JPY340,000 (USD3091) in 2017 (Figure 1)  . To control rising healthcare costs, Japan’s Ministry of Health, Labour and Welfare (MHLW) has established an ongoing Medium- and Long-Term Medical Care Expenditure Regulation Plan, which aims to improve prevention of lifestyle diseases and shorten hospital lengths of stay, with an emphasis on joint work between the national and prefectural governments (Figure 2) to address regional differences in costs .
Regional and community planning and implementation of health policies have been identified as an important component of maintaining the low costs and improving equity in healthcare . In addition to central policies emphasizing patient-centered health interactions, local efforts tailored to the particular needs of each regional health system are needed to foster equity and address regional
Figure 1. National medical expenditures per capita. JPY: Japanese yen.
Figure 2. Map of Japan’s prefectures. Eight regions: ■: Hokkaido (violet), ■: Tohoku (blue), ■: Kanto (green), ■: Chubu (light green), ■: Kinki (yellow), ■: Chugoku (orange), ■: Shikoku (pink), ■: Kyushu-Okinawa (red).
differences in quality, access, and costs of care. In an effort to further optimize expenditures, the Medium- and Long-Term Medical Care Expenditure Regulation Plan promotes regional difference analysis of medical expenditures.
To clarify regional differences in medical expenditures in Japan, we analyzed the relationship between the specific health examination coverage and medical care expenditure by prefecture of Japan using data from the National Database of Health Insurance Claims and Specific Health Checkups (NDB) Open Data Japan (2015) and Overview of 2015 National Medical Expenses.
The NDB was implemented in 2009 by the MHLW in order to plan health policies using national data. Additionally, the database is used for health research purposes. The NDB includes most of the administrative claims and health checkup data from insurers in Japan, covering approximately 98% of healthcare services in the country. The database contains information on prefecture, sex, age, dates of admission and discharge, and codes for diagnoses, procedures, and prescriptions .
Using data from the NDB and the Overview of 2015 National Medical Expenses   , we compared mean medical care expenditure per capita and mean proportions of persons receiving specific health examinations between Japan nationally and individual prefectures via One Sample t-test. To evaluate the relation-ship between per capita medical expenditures and the proportion of persons receiving specific health examinations, we calculated Pearson correlation coefficients. A ratio of JPY110: USD1 was used to convert currency (2014 value).
All statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS) version 26.0 (SPSS, Inc., Chicago, IL, USA). Statistical significance was set at p < 0.05. The study was approved by the Medical Ethics Committee of Ibaraki Prefectural University of Health Sciences (approval No. e211-r010620).
National medical expenditures were 42.3 trillion Japanese yen (3851 hundred million dollars), with a national per capita rate of JPY347,219 (USD3156). Per capita medical expenditure rates by prefecture ranged from JPY290,900 (USD2645) in Saitama Prefecture to JPY444,000 (USD4036) in Kochi Prefecture (Figure 3).
Figure 3. Comparison of mean national medical care expenditure per capita between Japan and prefectures. *p < 0.05 vs. Japan: **p < 0.001 vs. Japan. JPY: Japanese yen, USD: US dollar.
The proportion of persons receiving specific health examinations was 49.0% for Japan overall and ranged from 39.3% in Hokkaido Prefecture to 63.4% in Tokyo Prefecture (Figure 4).
We observed a significant negative correlation between per capita medical expenditures and the proportion of persons receiving specific health examinations (R = 0.553, p < 0.001) (Figure 5).
Substantial variation by prefecture exists in per capita medical expenditures and in the proportion of persons receiving specific health examinations. We found a significant negative correlation between per capita medical expenditures and the proportion of persons receiving health examinations: prefectures with lower per capita medical expenditures tended to have higher rates of specific medical
Figure 4. Proportion of persons receiving specific health examination by prefecture, fiscal year 2015. *p < 0.05 vs. Japan: **p < 0.001 vs. Japan. N: number of subjects.
Figure 5. Relationship among national medical care expenditure per capita and proportion of persons receiving specific health examination. JPY: Japanese yen.
It is possible that prefectures with high health awareness have high health examination rates and low expenditures. Health literacy is associated with healthy lifestyle, reduced lifestyle disease incidence, and participation in health screening and examinations .
Our findings suggest that increasing the proportion of persons receiving specific health examinations by prefecture would have a favorable impact on the medical care expenditure. Low health literacy is associated with less use of preventive services  and more unnecessary hospital admissions and emergency department visits . Engagement in specific health examinations could reduce medical expenditures through early detection of risky lifestyle behaviors or lifestyle diseases and other diseases at earlier stages. Less expensive behavioral interventions as primary or secondary prevention can prevent costlier pharmacological interventions required to treat more severe disease. For example, physical inactivity is associated with increased medical expenditures due to increased hospitalizations, physician visits, and medications . Relatively inexpensive lifestyle interventions targeting increased physical activity could prevent future costly treatments of disease sequelae, such as treatment for myocardial infarction related to physical inactivity and obesity. Likewise, lifestyle intervention in pre-diabetes reduces long-term medical expenditures , and progression from pre-diabetes to diabetes is associated with one-third higher medical expenditures compared to patients who did not progress to diabetes .
The strengths of the present study include use of standardized nationwide data on the majority of healthcare services in Japan. The observed correlation between per capita medical expenditures and the proportion of persons receiving specific health examinations is a novel finding and suggests an area for intervention to re-duce medical expenditures and improve population health.
However, some limitations also warrant mention. Data for our analysis was collected 5 years ago, in 2015; an analysis of more recent data is forthcoming. While the NDB covers the vast majority of healthcare expenditures in Japan, some expenditures, such as workplace injuries and injuries covered by automotive insurance, are not included . While administrative claims data are generally regarded as having high validity, they are subject to classification errors and provide limited information on potentially important confounders or covariates . Caution is warranted in interpreting the present results.
This study suggests that interventions to increase the proportion of persons receiving specific health examinations by prefecture could reduce per capita medical expenditures and reduce prefectural disparities in medical expenditures.
This article was supported in part by a JSPS KAKEN Grant-in-Aid for Early-Career Scientists (N.M. 19K19359).
This study was approved by the Medical Ethics Committee of Ibaraki Prefectural University of Health Sciences (Ibaraki, Japan).
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