Spatial clustering and pharmacy service performance in Seoul : evidence from card transaction data

The spatial distribution of community pharmacies in Seoul significantly influences both access to medicine and the financial viability of pharmacy operations. Using anonymized card transaction data from 2019 to 2022 across 3125 spatial blocks, this study measures clustering intensity via the Getis – Ord Gi statistic and evaluates spatial autocorrelation with Global Moran’s I. A panel random-effects regression model is applied to examine the relationship between spatial clustering and pharmacy performance, controlling for demographic, economic, and healthcare infrastructure variables. Results indicate that higher clustering intensity is significantly associated with reduced pharmacy performance, including a 1.71% decline in average daily sales and a 2.02% decrease in visit volume. Pharmacies located near tertiary hospitals and in high-income areas performed better, whereas those in clinic-dense zones exhibited demand dilution. These findings highlight that excessive spatial concentration may lead to market saturation and reduced service equity, suggesting that spatially informed policies are needed to support sustainable and equitable pharmaceutical care in dense urban markets.