## 5 Opportunities and Future Directions  
Integrating cutting-edge technologies into HIE systems has witnessed great advancements due to the huge efforts made from researchers and experts. This study aimed to answer the research questions mentioned in Section 2 as follows:  
* RQ1: The literature review showed that HIE systems have no unified architecture and should depend on the health organization requirements. However, most of the existing architectures have common components including data sources, HIE infrastructure, medical services, data analytics, security and privacy layers, and governance policies. * RQ2: Unfortunately, the building of HIE systems is facing severe challenges that may be classified into three main categories: technical, organizational and legal. To overcome such challenges, a deep understanding of system requirements with the help of experts should be performed to ensure highly efficient HIE systems. * RQ3: We demonstrated that blockchain and AI technologies play a vital role in increasing the security and privacy of modern HIE systems. On one hand, blockchain helps in ensuring the privacy of patient data through consensus algorithms and \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Ref.** & **Year** & **Method** & **Data Set** & **Performance** \\ \hline
[106] & 2022 & \
\begin{tabular}{c} Personal health \\ records sharing \\ scheme \\ \end{tabular} & Not available &
\begin{tabular}{c} Privacy = 90.16\%, \\ Integrity = 89.35\% \\ \end{tabular} \\ \hline
[107] & 2022 & \
\begin{tabular}{c} Authentication and \\ authorization framework \\ \end{tabular} & NA &
\begin{tabular}{c} Low execution \\ time, and \\ throughput, \\ high scalability \\ \end{tabular} \\ \hline
[49] & 2022 & \
\begin{tabular}{c} Blockchain-based \\ information scheme \\ management system \\ \end{tabular} & NA &
\begin{tabular}{c} Attack Resist = 91\% \\ Privacy = 92\% \\ Latency \textless{} 1000 ms \\ /100 users \\ \end{tabular} \\ \hline
[108] & 2021 & \
\begin{tabular}{c} Integration of \\ EMR and EHR \\ using blockchain \\ \end{tabular} & NA &
\begin{tabular}{c} High security, \\ and privacy \\ \end{tabular} \\ \hline
[109] & 2019 & \
\begin{tabular}{c} Combining machine \\ learning and \\ blockchain \\ \end{tabular} & NA &
\begin{tabular}{c} Accuracy = 93.57\%, \\ High efficiency \\ \end{tabular} \\ \hline
[56] & 2023 &
\begin{tabular}{c} AI and Public \\ Perception \\ \end{tabular} & 5128 papers & Not available \\ \hline
[110] & 2020 & \
\begin{tabular}{c} Blockchain and \\ AI-based multi \\ agent system \\ \end{tabular} & NA &
\begin{tabular}{c} Privacy = 93.2\%, \\ Integrity = 89.9\%, \\ Security = 93.77\% \\ \end{tabular} \\ \hline
[111] & 2023 & \
\begin{tabular}{c} Four-States blockchain \\ and AI framework \\ \end{tabular} & OPNET &
\begin{tabular}{c} Security = 94.8\%, \\ Success = 89.9\%, \\ Performance = 96.4\% \\ \end{tabular} \\ \hline
[112] & 2020 & \
\begin{tabular}{c} Machine learning \\ models \\ \end{tabular} & Data Breaches &
\begin{tabular}{c} Recall, Precision, \\ F1-score \\ Accuracy = 0.889 \\ \end{tabular} \\ \hline
[113] & 2019 & SVM, K-means & \
\begin{tabular}{c} Bitcoins \\ Transactions \\ \end{tabular} &
\begin{tabular}{c} High accuracy, \\ Confusion matrix \\ \end{tabular} \\ \hline
[114] & 2021 & \
\begin{tabular}{c} Machine learning \\ models, Blockchain \\ \end{tabular} & Kaggle &
\begin{tabular}{c} Accuracy, \\ Precision, \\ Recall, F1 score \\ \end{tabular} \\ \hline
[115] & 2021 & \
\begin{tabular}{c} Blockchain, \\ AI services \\ \end{tabular} & Web of Sciences &
\begin{tabular}{c} High efficiency, \\ low cost \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Integration of AI and blockchain into HIE Systems: A Summary. smart contract mechanisms. On the other hand, AI represents an extra security layer that could detect any risky transactions routed on blockchain networks based on learning models.