Association between rurality and mortality from major diseases in Japan: an ecological study

This study aimed to examine rural-urban disparities in healthcare outcomes in Japan using the Rurality Index for Japan (RIJ). It evaluated the association between rurality and mortality from five major diseases prioritised by the Japanese government, accounting for socioeconomic and demographic factors.

An ecological study using publicly available data at municipal and administrative district levels.

All municipalities and administrative districts within government-designated cities in Japan.

A total of 1897 municipalities and administrative districts were analysed, excluding areas with zero population. The total number of the population was approximately 126 million.

Rurality was measured using RIJ.

Standardised mortality ratios (SMRs) were used for acute myocardial infarction (AMI), cerebrovascular diseases (stroke and haemorrhage), cancer and suicide. The standardised claim ratio (SCR) for diabetes outpatient care served as a proxy measure due to the unavailability of mortality data.

Greater rurality, as quantified by RIJ, was associated with higher SMRs for cerebrovascular diseases and male suicide. A dose-response relationship was observed among SMRs for cerebrovascular disease and male suicide, whereas AMI mortality was higher in rural areas but lacked a strict dose-dependent trend. No significant association was found between rurality and cancer mortality or diabetes in outpatient SCR. Additionally, RIJ was positively correlated with the proportion of older adults (Spearman's ρ=0.67) and the Arial Deprivation Index (ρ=0.55).

These findings highlight the need for targeted rural health policies that improve access to emergency care and mental health services.