Implementation of decentralized clinical trials in Korea from a resource-based perspective

Clinical trials in South Korea are heavily concentrated in Seoul, limiting patient access in other regions. We conducted a cross-sectional ecological study of 17 Korean administrative divisions to assess regional infrastructure readiness for decentralized clinical trial (DCT) implementation, using data from the Health Insurance Review and Assessment Service (2024), the National Health Insurance Service (2024), and the Ministry of Food and Drug Safety (2024 to 2025). Provincial densities for four resource domains (specialists, nurses, beds, and medical equipment) were calculated per 100,000 patients and normalized to Seoul (= 1.00). Area-specific composite indices for four therapeutic areas were computed as the capped geometric mean of specialist and equipment densities, and an overall infrastructure index as the capped geometric mean of all four domain densities. Trial density was derived from 1,924 approved trials yielding 7,760 trial-center pairs (99% mapping rate). Among the 16 non-Seoul provinces, bed density was the most dispersed (coefficient of variation [CV] = 0.39, range 0.58 to 2.91), whereas specialist density was the most Seoul-concentrated of the four domains: no non-Seoul province reached 80% of Seoul's level (CV = 0.23, range 0.42 to 0.79). The four therapeutic-area composite indices showed comparable dispersion (CV 0.15 to 0.23; composite infrastructure CV 0.16; Pearson r = 0.72). Gwangju exhibited the largest gap between infrastructure capacity (index 0.94) and trial activity (density ratio 0.18). Clinical trial activity in Korea is disproportionately low relative to infrastructure, and region-specific DCT strategies matched to local resource profiles can provide a practical framework for balanced trial participation.