Accurate and complete patient data is a valuable asset for patients and clinicians who may be performing further treatments (Chen et al., 2018). Secure storage with easy accessibility and the protection of the privacy of medical data are therefore important issues. Usman and Qamar (2020) have developed a blockchain-based system for storing highly sensitive and private patient data with which these health data can be efficiently stored and securely distributed. The solution also ensures the data protection of medical records through the use of a permissioned blockchain based on the Hyperledger platform (Cachin, 2016). This system also allows patients to play an active role in managing their medical records and to be in control of who can add new records and view their medical history (Usman and Qamar, 2020).

However, with the increasing use of electronic solutions for processing medical information, the amount of data to be processed is also increasing rapidly (Li et al., 2018). The medical data can easily be stolen, manipulated or deleted while they are being stored and processed, which is why Li et al. (2018) have developed a novel blockchain-based data storage system for relatively large amounts of data. With the system, users can permanently save important data and continuously check for authenticity. During the treatment process, patient data in this study is created in text and multimedia formats, then subsequently protected against unauthorized access and stored in encrypted form. This is done using various cryptographic algorithms and file storage schemes as well as an identity information system in which the user identities are not linked to the medical data. The storage takes place in the form of transactions that are transmitted to the blockchain network and collected and stored in blocks of a defined data size. If the data in the database is then manipulated or damaged, the data information can be accessed and checked via the blockchain (Li et al., 2018).

The healthcare industry already manages personal patient data, diagnostic reports and medical prescriptions or reports in an electronically centralized manner (Kumar et al., 2020). However, with this it is difficult to protect the privacy of the patient, which is why Kumar et al. (2020) developed a blockchain-based system for storing medical data with distributed off-chain data storage via the Interplanetary File System (IPFS) (Protocol Labs Inc., 2021). For this purpose, a consortium blockchain (permissioned) framework with a private identity-based access control for the storage of special data information is implemented in the study. Furthermore, an IPFS off-chain storage model is implemented to manage the original patient data, since in the blockchain, according to Kumar et al. (2020), only a cryptographic hash value (Pilkington, 2016) of the patient information is stored due to the scalability.

Zhou et al. (2018) have developed a blockchain-based storage system for medical health insurance data that is tamper-proof and offers users a high level of credibility for their data. This system is designed to help insurance companies track and receive relevant medical information about patients both rapidly and easily (Zhou et al., 2018).

Before, the secure storage of medical records was still about the secure, digital storage and processing as well as the distribution of mostly incoherent patient data (e.g., diagnoses by a specialist for different patients), it is now more about the storage, processing and, in particular, accessibility of temporal and patient-specific related data in the form of an electronic medical record.

The use of medical patient files for various purposes always requires the consent of the patients, who currently grant or refuse these mostly in paper form and then no longer have any control or overview over their files (Tith et al., 2020). Tith et al. (2020) have developed a system with which patients can flexibly manage their consents and health organizations can also efficiently obtain and manage these consents for various purposes. The electronic system uses a dedicated access control based on a permissioned blockchain with Hyperledger implementation. In this study, all metadata of patient records, consents and data access are immutably stored in the blockchain and shared by the participating parties. In addition, a program code based on smart contracts or rather chaincode (Cachin, 2016) was created, which according to Tith et al. (2020) automates the business logic for managing patient consent.

However, strict regulation and bureaucratic inefficiency have greatly slowed the development of electronic medical records in the past (Azaria et al., 2016). Driven by new developments in electronic information technology, electronic records are now enjoying increasing acceptance (Fan et al., 2018). New technical innovations as well as an increased interest of patients in their personal data caused Azaria et al. (2016) to develop a new, decentralized data management system for the treatment of patient data based on blockchain technology. The system provides patients with a comprehensive, unchangeable log and easy access to their medical data, regardless of the facility and software system. The decentralized data system of these study manages authentication, trustworthiness, accountability and data exchange through the use of characteristic blockchain mechanisms such as smart contracts (Christidis and Devetsikiotis, 2016), mining (Christidis and Devetsikiotis, 2016) and proof of work (Gervais et al., 2016). In addition, it can be integrated into existing local data storage solutions and enables a data economy between patients, researchers and authorities (Azaria et al., 2016).

Generally, digital data for the same patient is collected and stored in different hospitals (Fan et al., 2018). However, for security and data protection reasons it is difficult to summarize or exchange the data between the institutions, which is why Fan et al. (2018) developed a blockchain-based information management system that cryptographically processes patient information and enables a secure exchange of information. With this system, extensive datasets can also be securely managed and patients, doctors, researchers and other third parties can easily have secure access to local databases of various institutions (Fan et al., 2018).

Healthcare management encompasses many different processes (e.g., managing finances, patients, legal issues etc.) and medical workflows related to patient care (Khatoon, 2020). Khatoon (2020) has developed a management system based on smart contracts for the intelligent and digital management of medical data in the healthcare sector and for the optimization of complex medical processes. During the implementation, representations of real medical files are created and various data of medical work processes are stored de-centrally in a blockchain. Access rights to metadata, authorization management and authorization rules for data access are then defined via smart contracts. The information is cryptographically secured and stored in a special, compressed form in a blockchain block (Khatoon, 2020).

Healthcare supply chains have a significant impact on patient safety and the quality of medical treatments (Jayaraman et al., 2014). Effective supply chain management is crucial in healthcare in order to build the best possible procurement, ordering, forecasting and sales system, as well as to reduce costs and improve patient outcomes (Omar et al., 2021). For this reason Omar et al. (2021) have developed a blockchain-based system built on smart contracts and a decentralized storage system that improves the contract process for supply chains in the healthcare system. In this process, manufacturers, sellers, buyers and healthcare providers are connected to one another via a decentralized Ethereum (Buterin, 2014) network. Transparency, data origin and data immutability are already defined in the contract process and used for the implementation of automated procurement processes (Omar et al., 2021).

Blockchain technology has the potential to handle and track supply chain processes in healthcare and other areas very efficiently (Abbas et al., 2020). Abbas et al. (2020) have developed a novel management and recommendation system for drug supply chains based on blockchain and machine learning (ML) (Beam and Kohane, 2018). The system consists of a permissioned Blockchain, through which the drug supply chain is continuously monitored and authentically tracked, as well as an ML module that has been trained with a drug review dataset to recommend the best-rated drugs (Abbas et al., 2020). The ML module is also integrated into the blockchain via a Representational State Transfer Application Programming Interface (RESTful API) (Maleshkova et al., 2010).

Supply chains are complex structures that span multiple organizational and geographical boundaries and represent a critical infrastructure for medical services, especially in the healthcare sector (Musamih et al., 2021). For this, an efficient traceability of products in supply chains in the healthcare sector based on a permissionless blockchain was developed by Musamih et al. (2021). With this solution, products are automatically tracked via smart contracts and decentralized off-chain storage, intermediaries are superfluous and the transaction history is unchangeably and securely documented (Musamih et al., 2021).

In order to track, identify, communicate with and localize products and product data, radio-frequency identification (RFID) systems are increasingly being used in the healthcare sector (Figueroa et al., 2019). Figueroa et al. (2019) have developed a product-based access control system for RFID systems that executes access guidelines from a decentralized application based on a permissionless blockchain. With this implementation, for example, surgical instruments can be equipped with an RFID tag and their use and location can be tracked (Figueroa et al., 2019).