Patientcentric medication history recording system using blockchain Medication errors are one of the problems to be solved not only in Korea but also across the world. To prevent a medication accident in advance, the comprehensive management of individual medication history is essential. Currently, in the hospitalcentric Personal Health Record system, if the patient is prescribed medicines at multiple hospitals, heshe needs to go to the hospital where a medicine was prescribed to get the corresponding needs such as prescription or medical certification to record the prescription information on hisher own. Alternatively, the patient needs to record the prescription information on hisher own. This is very time consuming, inconvenient, and even worse, not reliable method because of input errors. Therefore, in this study, we developed Patientcentric medication history recording system using blockchain, which is directly capturing QR code printed on the envelop by drug store based on prescription. All the information are stored using the hash value of the data in a blockchain and it prevents the tampering of the data. In addition, this system adopted Fast Healthcare Interoperability Resources, which is the international health information exchange standard, as way to improve interoperability.

Scaling Blockchains to Support Electronic Health Records for Hospital Systems Electronic Health Records (EHRs) have improved many aspects of healthcare and allowed for easier patient management for medical providers. Blockchains have been proposed as a promising solution for supporting Electronic Health Records (EHRs), but have also been linked to scalability concerns about supporting realworld healthcare systems. This paper quantifies the scalability issues and bottlenecks related to current blockchains and puts into perspective the limitations blockchains have with supporting healthcare systems. Particularly we show that well known blockchains such as Bitcoin, Ethereum, and IOTA cannot support transactions of a large scale hospital system such as the University of Kentucky HealthCare system and leave over 7.5M unsealed transactions per day. We then discuss how bottlenecks of blockchains can be relieved with sidechains, enabling wellknown blockchains to support even larger hospital systems of over 30M transactions per day. We then introduce the PatientHealthchain architecture to provide future direction on how scaling blockchains for EHR systems with sidechains can be achieved.