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.

On the Design of a BlockchainasaServiceBased Health Information Exchange (BaaSHIE) System for Patient Monitoring The digitization of health records has massively increased Health Information Exchange (HIE) activities among different practitioners, but it has lagged behind Electronic HealthMedical Records (EHRsEMRs) adoption for numerous reasons, including confidentiality, interoperability, integrity, and privacyrelated concerns. In this paper, we present a BlockchainasaService based solution for HIE (BaaSHIE). In particular, our design work involves the use of a private Blockchain and smart contracts as access control manager to medical records. In order to maintain high level of performance for applications, thus that such applications could be economically viable, all of the health data are encrypted and stored into a decentralised InterPlanetary File System (IPFS) and the hash of the assets URI is stored in blockchain. Our experimental results demonstrate the feasibility of the proposed approach in offering a decentralized and finegrained accessibility mechanism for the patient and the doctor in a given healthcare system.