BACKGROUND: The financial burden of kidney replacement therapy (KRT) is considerable, and detailed information on KRT costs is essential for managing these huge healthcare costs. However, cost analyses for kidney transplantation (KTx) are limited in Japan. This study aimed to report the healthcare costs of KTx recipients in Japan based on large medical receipt data. METHODS: This cost analysis of KTx recipients using the Japan Medical Data Center Claims Database between January 2005 and August 2020 identified living donor KTx (LDKT) and deceased donor KTx (DKT) recipients. The primary outcome was the total direct healthcare costs of KTx recipients. As an exploratory analysis, we examined the factors that contributed to the increase in the costs of LDKT. RESULTS: In total, 84 LDKT and 17 DKT recipients were included in this study. The total healthcare costs for LDKT and DKT recipients during the first year after KTx were 6,639,982 and 6,840,450 JPY/year, respectively. However, after the second year post-KTx, total healthcare costs decreased to 1,735,931 and 1,348,642 JPY/year for LDKT and DKT recipients, respectively. During the first year, inpatient costs accounted for >
70% of the total healthcare costs, whereas pharmaceutical costs accounted for more than half after the second year post-KTx. The use of everolimus and male sex were associated with higher and lower total healthcare costs in the first and subsequent years after LDKT, respectively. CONCLUSION: Using large-scale administrative databases, this study revealed the total healthcare costs of KTx in Japan and provided valuable information for the health technology assessment of KTx.