Regional Disparities in Domiciliary Dental-Care Utilization and Their Association with Pneumonia Mortality in Japan:...

Pneumonia is the leading cause of death among older adults, and oral care contributes to pneumonia prevention. Disparities in access to dental care and socioeconomic factors may influence service use among community-dwelling older adults. Therefore, in this study, we examined the association between the regional utilization of domiciliary dental care (DDC) and pneumonia mortality, as well as the impact of area-level socioeconomic conditions.

In this nationwide ecological cross-sectional study, we used publicly available data from 335 secondary medical areas across Japan in 2023. The primary outcome was the standardized mortality ratio (SMR) for pneumonia. The primary explanatory variable was the DDC utilization ratio, and the secondary analysis used per-capita claims (PCC). Area-level socioeconomic status (area SES) was defined using the area deprivation index. Healthcare resources were included as covariates, and a Bayesian spatial analysis was performed using a conditional autoregressive model.

Moran's I for the SMR for pneumonia was 0.361 (p < 0.01). In the conditional autoregressive model, the DDC ratio was significantly associated with the SMR for pneumonia (relative risk [RR]: 1.04; 95% confidence interval [CI]: 1.002-1.08). However, area SES showed no significant association (RR: 1.05; 95% CI: 0.998-1.10). The PCC was also significantly associated with the SMR for pneumonia (RR: 1.06; 95% CI: 1.01-1.11), whereas area SES showed no significant association (RR: 1.05; 95% CI: 0.998-1.10). The PCC were weakly and inversely correlated with area SES.

Both the DDC ratio and PCC were positively associated with the SMR for pneumonia, suggesting that DDC is concentrated among frail older adults at high risk. Socioeconomically deprived areas tended to have fewer claims per patient, implying that regional disparities hinder preventive and continuous dental care. Strengthening preventive interventions and improving access to support tailored to local health needs and socioeconomic contexts are required.