International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 08 Issue: 06 | June 2021 www.irjet.net p-ISSN: 2395-0072 © 2021, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 1123 A Survey: Blockchain-based Electronic Health Record System Gaurang Awatade 1 , Gaurav Kasure 2 , Suyog Padole 3 , Yash Choudhary 4 , Shital Sungare 5 , Anil Kumar Gupta 6 1,2,3,4 Student, Department of Computer Engineering, Dr. D. Y. Patil Institute of Technology, Pune, India 5 Professor, Department of Computer Engineering, Dr. D. Y. Patil Institute of Technology, Pune, India 6 Senior IEEE Member ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - The emergence of new technologies brings in lots of features, which can increase the efficiency of existing systems. One such system which needs improvement is the management of health record. The existing Electronic Health Record (EHR) system faces some challenges regarding data security, interoperability, management, etc. Therefore, hospitals must use more efficient and secure technology to implement Electronic Health Record system. This can be achieved by Blockchain technology. Blockchain Technology is a very interesting research area, and now it is at its peak in revolutionizing the way in which we used to handle the data regarding healthcare while storing it and finally during its utilization. Various blockchain-based solutions have been proposed for the same. The motive of this literature is to put forward a comprehensive survey of these solutions. Key Words: Electronic Health Record, Blockchain, Decentralized, Interoperability, Immutability, Scalability, Hyperledger Fabric. 1.INTRODUCTION The earlier hand-written mechanism, i.e. paper-based system, was used to store the patient's health record [1]. This system was not efficient as it had some issues, out of which one was; this system was a time-consuming process as each record was required to be stored manually. Other issues include: if any patient visited multiple hospitals, then multiple records would have to be maintained for the same patient, which leads to data redundancy, this system was not tamper-proof, which means it wasn't secured system if any record got misplaced, then its recovery was a difficult task. All these problems state that this was insecure and inefficient. Therefore, the need for a digital system arises to overcome such challenges. Hence, the Electronic Health Record System was introduced to store the medical records of patients. Many hospitals are using this Electronic Health Record system due to its benefits such as security and high efficiency than the paper-based system. It efficiently stores the health records like lab reports, MRI reports, etc. Though this system is more efficient than earlier, one issue that still occurs in this system is data redundancy. It also has some other issues related to Interoperability, Information Asymmetry, Security, etc. [1] that are explained below:  Interoperability: Exchange of data between different organizations or hospital must be effective. Records that are stored must be exchangeable so that they can be used further. As there is not a universally defined standard various hospitals may have systems with different technical and functional capabilities, which may lead to a lack of interoperability [2].  Information Asymmetry: It refers to one party having better access to the system than other parties [1]. As this is a centralized system, if patients want to access their records, they would have to follow a long process which is time- consuming because only the hospitals or organizations have access to the patient's record.  Security: One of the significant drawbacks of an EHR system is data security. Hospital database systems are often the target of hackers. Hence the security of EHR is compromised. Due to these challenges, the need for a more secured and efficient health record system arises. One such technology which is secured and can overcome these challenges is Blockchain. 1.1 Overview of Blockchain: Blockchain is a decentralized system created by Satoshi Nakamoto [3] as the technology behind Bitcoin, a popular cryptocurrency. Soon this backend technology became popular and began to spread its branches in various fields, starting from digital currency to finance, supply chain management, healthcare, market monitoring etc. Blockchain technology contains a chain of blocks that are consecutively connected. In each of these blocks, a specific number of transactions are stored. This chain can continuously grow in one direction as more transactions are added. This chain is stored in a decentralized manner, meaning each node in the blockchain network holds these records. The blockchain contains transactions in groups that are hashed together. Thus any change in any of the transactions will change the hash code generated by each of the consecutive blocks. Therefore hackers have to change the whole series of blocks in the chain. This is not possible, given the number of blocks in the chain is massive. Hence security is provided, and they are managed by a peer-to-peer network. Blockchain has three types: private, permissionless and hybrid. Cryptocurrencies like Bitcoin and Ethereum are