Association between spatial access and hospitalization for ambulatory care sensitive conditions: A retrospective cohort study using claims data.

Background: Hospitalization for ambulatory care sensitive conditions (ACSCs) is potentially preventable with timely and effective primary care but may increase owing to poor access. Spatial access inequalities exist between Japan and other countries. This retrospective cohort study examined the association between admission for ACSC and spatial accessibility to primary care. Methods: We used claims data and spatial data of 50-74 years-old beneficiaries of the National Health Insurance program in a large city in Japan from April 2013-March 2014 and followed them until March 2015. We used a multilevel Poisson regression model to assess the association between the number of ACSC admissions, the distance to the nearest clinic, and the number of physicians in a given area, adjusting for age, gender, comorbidities, number of visits, and household income. Results: Among 126,666 eligible beneficiaries (mean age 65.8 years, 54% were women), 1,793 (1.4%) were hospitalized for ACSCs. The ACSC admission rate was significantly higher in those with a distance to the nearest clinic of >1 km than in those with <0.3 km (incident rate ratio [IRR] 1.32, 95% confidence interval [CI] 1.03-1.69). In the stratified analyses, a longer distance to the nearest clinic was associated with higher ACSC admission rates among women (≥0.3 km and <0.5 km: IRR 1.48, 95% CI 1.01-2.17; ≥0.5 km and <1 km: IRR 1.74, 95% CI 1.19-2.56; >1 km: IRR 1.98, 95% CI 1.29-3.03, respectively) and those aged ≥65 years (≥0.3 km and <0.5 km: IRR 1.38, 95% CI 1.07-1.79; ≥0.5 km and <1 km: IRR 1.38, 95% CI 1.06-1.80; >1 km: IRR 1.48, 95% CI 1.10-1.98). Conclusion: Unfavorable spatial access was associated with ACSC admissions, particularly among women and older adults.