Table 1.

Comparison of Studies.

Study	Approach & Details	Key Findings/ Contribution	Limitations
[21]	Decentralized auditing scheme for IIOT using Ethereum smart contracts. Supports batch and dynamic auditing.	Ensures strong security of data auditing using nonce, delay function, BLS signature, and bilinear pairing technology. Supports batch and dynamic auditing, paying for auditing and punishing malicious behavior using smart contract deposits. Absence of Audit Trails and Compliance Auditing information	Absence of Audit Trails and Compliance Auditing information
[22]	Introduces HSC-PRE scheme for auditable, EHR systems using blockchain technology.	Proposes HSC-PRE scheme addressing security challenges of EHR systems, integrates with blockchain for auditability and interoperability. Absence of Audit Trails information and Compliance Auditing	Absence of Audit Trails information and Compliance Auditing
[34]	Utilizes EHR audit log data to analyze contextual factors affecting clinical process outcomes.	By utilizing EHR audit log data, finds that greater prior team experience, especially with acute ischemic stroke cases, leads to shorter DNT. Not backbone by Blockchain Absence of Audit Trails and Compliance Auditing information	Absence of Audit Trails and Compliance Auditing information
[24]	Utilized Ethereum blockchain EHR+ IoMT Healthcare data sharing with a decentralized Trusted Third Party Auditor (TTPA).	Using of cloud servers might generate security issues Absence of Audit Trails and Compliance Auditing information	Absence of Audit Trails and Compliance Auditing information
[37]	Utilized Hyperledger blockchain for EHR management, access control and for audit.	Proposed a mechanism to save hashes of stored EHR data and control access when retrieving it helpful for auditing. Lacks detailed discussions on the implementation, experiments, and results regarding EHR auditing, Absence of Audit Trails and Compliance Auditing information	Absence of Audit Trails and Compliance Auditing information