There is currently a strong focus worldwide on the potential of large-scale Electronic Health Record (EHR) systems to cut costs and improve patient outcomes through increased efficiency. This is accomplished by aggregating medical data from isolated Electronic Medical Record databases maintained by different healthcare providers. Concerns about the privacy and reliability of Electronic Health Records are crucial to healthcare service consumers. Traditional security mechanisms are designed to satisfy confidentiality, integrity, and availability requirements, but they fail to provide a measurement tool for data reliability from a data entry perspective. In this paper, we introduce a Medical Data Reliability Assessment (MDRA) service model to assess the reliability of medical data by evaluating the trustworthiness of its sources, usually the healthcare provider which created the data and the medical practitioner who diagnosed the patient and authorised entry of this data into the patient's medical record. The result is then expressed by manipulating health record metadata to alert medical practitioners relying on the information to possible reliability problems.
Key words: Electronic Health Records, Trustworthiness, Reputation,Reliability, Subjective Logic
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The healthcare domain stands to gain enormously from the increased adoption of Information and Communications Technologies (ICT). Electronic Health Record (EHR) systems are the latest evolution of healthcare ICT, and countries such as Australia, the United Kingdom, and the USA are working on plans for national EHR systems .
An Electronic Health Record is defined by Iakovidis  as "digitally stored healthcare information about an individual's lifetime with the purpose of supporting continuity of care, education and research, and ensuring confidentiality at all times". It is a mechanism for integrating healthcare information currently collected in both paper files and Electronic Medical Record (EMR) databases by a variety of healthcare providers . Electronic Health Records (EHRs) enable the efficient communication of medical information, and thus reduce costs and administrative overheads , . Furthermore, they aim to provide authorised healthcare professionals with legitimate access to a wealth of historical medical data at one access point.
However, to achieve these potential benefits, the healthcare industry needs to overcome several significant obstacles, in particular having confidence in the reliability of the EHRs' medical data. Concern about data reliability is a crucial factor that may have a strong effect on how medical practitioners use EHRs . This issue arises because the EHR's medical data is composed from different healthcare providers' Electronic Medical Record (EMR) systems and from paper-basedmedical reports and referrals that patients received from those healthcare providers who do not have an EMR system or an electronic connection to the EHR system. By using the EHR system, a medical practitioner will be exposed to historical medical data with varying levels of reliability; the data might originate from a healthcare provider that does not satisfy patient safety requirements, e.g. is known to habitually enter inaccurate or incomplete data, or be entered by a medical practitioner who fails to satisfy medical safety practices, e.g. is known to violate medical procedures. As a consequence, the reliability of the EHR medical data depends on the trustworthiness of the source and the creator of the captured data. However, in medical practice medical data is usually assumed reliable a priori so, in the absence of a reliability evaluation technique, all data will be valued equally. In the following scenario we demonstrate the harmful impact that may occur if a measure of medical data reliability is not incorporated in the EHR system. …