## 2 Overview of Health Information Systems  
According to [PERSON] et al. [11] HIS can be defined as an IS that is used in a Healthcare setting and consists of multiple components that are related and dependent on each other. The main functions of an HIS are to gather, process, store, and distribute information of healthcare providers and their stakeholders, thereby improving the efficiency and effectiveness of healthcare [11; 12]. HIS consists of humans, procedures, technology, and the interaction between them [13]. HIS may also be described as a socio-technical subsystem in hospitals that consist of information processing systems and human or technical staff that perform the processing, supporting hospital affairs [14]. The 1960s saw the introduction of computerized systems targeting healthcare [15]. The aim of these systems was to automate some operational and administrative tasks and manage staff and patient financials. The evolution in medicine and medicaid sciences and the introduction of evidence-based medicine led to increased focus on medical records [15; 16]. The advances in IT and systems in 1970s led to the introduction of EHR. [PERSON] el al. [17] define EHR as the virtual record of all health-related events of an individual during his whole lifespan that includes but is not limited to medication history and allergies, admissions, and/or outpatient clinic visit. International Organization for Standardization (ISO) defines EHR as a repository of information regarding the health status of a subject of care, in computer processable form [18]. Subsequently, decision support features were included in HIS to provide better diagnostics and treatment [15; 19; 20; 21; 22]. HIS has also benefited from the wider adoption of IT and the improvements in the communications and computer networks. The availability of internet through multiple data networks has led to the introduction of many centralized and decentralized systems that facilitate information sharing and distribution between different parties. These systems are termed as Health Information Exchange (HIE). An HIE is a regional or national organization that facilitates the electronic sharing of healthcare data among providers, facilities, health information organizations, government agencies, and patients [23]. HIE allow healthcare organizations to appropriately access and securely share a patient's medical information electronically, before, during, and at the conclusion of an episode of healthcare [14; 23]. HIS play an important role in this sharing through the sharing of EHR through HIE. However, there are several interoperability challenges when it comes to sharing EHR that still need to be resolved using standardization at several layers of technology, data, human, and institutions [24]. Even when interoperability may not be an issue, HIEs report that EHS vendors and health systems engage in information blocking [25]. Cloud-based HIS may alleviate some of the technical concerns of sharing EHR data via HIEs, however, the idea of collecting personal health information into a single repository elicits serious security and privacy concerns from patients, and control and ultimate usage concerns from providers [26]. Currently, with the expansion of cloud services and providers, concepts like e-health and Personal Electronic Health Records (pEHR) have been introduced to increase patient empowerment [16; 20; 27; 28]. Due to the advancement in IT, and medical and medicaid sciences, current HIS have become more complex and capable [12] and are expected to perform the following functions [14; 15]:  
* Clinical information management: This relates to patient information and includes EHR, information extracted from the internal submodules, or the integration with other third-party systems. These sources can be from laboratories, radiology, inpatient, outpatient, emergency department, or pharmacies. Clinical decision support, knowledgebase, and order communication systems are also considered in this category.