## 5 Critical Challenges of BC Adoption in HMS  
Although blockchain is very efficient in overcoming the issues and loopholes in healthcare management systems, there are still challenges in integrating BC into HMS. There is still hesitation in adopting the BC technology by different organizations and people. Some of the critical challenges are identified and discussed below:  
* **Data Storage and Scalability** The blockchain gets heavier every day as a result of the rising transaction volume. The network may have fewer nodes with sufficient processing capacity to handle and validate data on the blockchain as a result of the increased storage and computational power demands. However, large block sizes could slow down propagation and result in blockchain branches. Therefore, voluminous data storage and scalability are challenging issues [1]. * **Data Access and Reliability** The decentralized idea of BC has both strengths and weaknesses. A decentralized network avoids the risk of a single point of failure, but still, the blockchain suffers from data access and reliability issues. It is because some blockchain characteristics leave BC vulnerable to a digital attack. As a result, one of the key challenges in blockchain is data access and reliability [4, 75]. * **Privacy and Security** Encryption provides protection and security, but healthcare stakeholders still believe the accessibility of a database, even in encrypted form, is a critical problem. Therefore, in the context of blockchain, it is crucial to managing access control appropriately [17]. Healthcare information is acquired from several stakeholders, which may result in unintentional invasions of protection, privacy, and security. Therefore, it is necessary to analyze and foresee the information before granting access control [4, 49]. * **Complex Decentralized Architecture** Since blockchain combines complex technologies, it is tough to adapt to working on blockchain frameworks. In addition, medical services, doctor suppliers, and insurance payers still rely on paper-based records rather than electronic medical records, so adapting \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Key Factors** & **Traditional HMS** & **Blockchain-Based HMS** \\ \hline Documentation & More & Less/Not required \\ \hline Data storage & Manual/Centralized & Decentralized \\ \hline Data availability & Delayed & Up to date \\ \hline Integrity & Less & More \\ \hline Security & Less & More \\ \hline Immutable records & No & Yes \\ \hline Consensus & No & Yes \\ \hline Single trusted record & Multiple copies & Single universal copy \\ \hline Access & Internal & Anywhere \\ \hline Patient-centric & No & Yes \\ \hline Hash key & No & Yes \\ \hline Data recovery/Backup & Vulnerable to data loss & Minimal risk of data loss \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Traditional HMS and blockchain-based HMS. the blockchain framework is challenging [68]. It is exceptionally hard to arrange every one of these elements to receive blockchain as an innovation [4]. * **Lack of Legislative Standards** For the blockchain-based healthcare system to function, both public and private blockchains must be interoperable. This highlights the requirement for internationally coordinated standards and agreements that span national boundaries and jurisdictions [17]. Numerous associations, such as IEEE and ITU, are attempting to deliver new BC innovation norms that are yet to be finalized. Various tasks are going on in blockchain principles by IEEE to make blockchain usage for the future; however, it requires legitimate rules, laws, guidelines, and approaches [4,9]. * **Ownership and Governance** The development of suitable rules for global governance rights of ownership relating to medical transactions for the blockchain-based healthcare system is challenging. It will be hard to convert the current regulatory framework to the new administration's policy objectives managing blockchain's digitally documented, automated, and ubiquitous nature.