The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. Please improve this article and discuss the issue on the talk page.(March 2014)
Health information exchange (HIE) is the mobilization of healthcare information electronically across organizations within a region, community or hospital system. In practice the term HIE may also refer to the organization that facilitates the exchange.
HIE provides the capability to electronically move clinical information among disparate health care information systems while maintaining the meaning of the information being exchanged. The goal of HIE is to facilitate access to and retrieval of clinical data to provide safer and more timely, efficient, effective, and equitable patient-centered care. HIE is also useful to public health authorities to assist in analyses of the health of the population.
HIE systems facilitate the efforts of physicians and clinicians to meet high standards of patient care through electronic participation in a patient's continuity of care with multiple providers. Secondary health care provider benefits include reduced expenses associated with:
the manual printing, scanning and faxing of documents, including paper and ink costs, as well as the maintenance of associated office machinery
the physical mailing of patient charts and records, and phone communication to verify delivery of traditional communications, referrals, and test results
the time and effort involved in recovering missing patient information, including any duplicate tests required to recover such information
According to an internal study at Sushoo Health Information Exchange, the current method of exchanging patients' health information accounts for approximately $17,160 of expenses annually for a single-clinician practice.
Formal organizations are now emerging to provide both form and function for health information exchange efforts, both on independent and governmental/regional levels. These organizations are, in many cases, enabled and supported financially by statewide health information exchange grants from the Office of the National Coordinator for Health Information Technology. These grants were legislated into the HITECH components of the American Reinvestment and Recovery Act in 2009. The latter organizations (often called Regional Health Information Organizations, or RHIOs) are ordinarily geographically defined entities which develop and manage a set of contractual conventions and terms, arrange for the means of electronic exchange of information, and develop and maintain HIE standards.
In the United States, federal and state regulations regarding HIEs and HIT (health information technology) are still being defined. Federal regulations and incentive programs such as "Meaningful Use", which is formally known as the EHR Incentive Program, are rapidly changing the face of this relatively new industry. In addition to changes driven by federal activities the lessons learned in the ongoing implementation of some state-sponsored HIEs (such as the North Carolina HIE) and the fluctuating nature of health care regulations at the level of the state governments themselves is leading to additional refinement. However, HIEs and RHIOs continue to struggle to achieve self-sustainability and the vast majority remain tied to Federal, State, or Independent grant funding in order to remain operational. Some exceptions exist, such as the Indiana HIE.
Storage and Gathering of Information in HIEs
Data Architecture Models for HIEs
There are two main models for the data architecture of Health Information Exchanges. One is a federated, or decentralized model, and the second is a centralized one. There is also a hybrid model that contains elements of both. In a centralized HIE there is a central (or master) database which holds a complete copy of all of the records of every patient contained in the HIE. In a federated HIE there is no master database.
In a federated model each health care provider is responsible for maintaining the records of their individual patients. In this model the main function of the HIE is to facilitate providers with exchanging patient records among themselves as the need arises. For example, if a physician in a federated HIE requests the records of Patient Y a query is sent to each server in the system asking to return any records that they have pertaining to Patient Y. Each federated HIE may accomplish this in a slightly different way, but the salient distinction is that in a federated model there is no central database from which a previously compiled comprehensive medical record is stored and can be downloaded.
In short, in a federated HIE records are exchanged electronically among providers when they need them. In a centralized model all patient information is uploaded to a single database from which any provider in the HIE can download a patients full medical record. 
There are two methods for gaining patient consent. One is explicit consent and is termed Opt-In. With this method a patient is not automatically enrolled into the HIE by default and generally must submit a written request to join the Health Information Exchange.
The other method is implicit patient consent and is termed Opt-Out. In this method patients give implicit consent to join an HIE when they agree to use the services of a health care provider who is submitting data into an HIE and sign the provider's Notice Of Privacy Practices. In this model patients can request to Opt-Out of the HIE, generally with a written form.
DHIN is a non-profit public-private partnership enacted by the Delaware General Assembly in 1997, for the benefit of all citizens of Delaware to advance the creation of a statewide health information network and to address Delaware's needs for timely, reliable and relevant health care information. DHIN has adopted regulations to govern its operations and has policies and procedures in place to support privacy and security of patient information. DHIN enhances a health care information exchange started in May 2007. In February 2012, The Delaware Health Information Network announced full participation of all acute care hospitals and skilled nursing facilities in the state, along with the vast majority of Delaware providers, in the first statewide community health record. As of June 2013, DHIN has attracted the participation of 97 percent of Delaware providers, tracks nearly 88 percent of Delaware's population, and delivers more than 10 million clinical results and reports to participating providers annually.
The Friesland Regional Cardiology Network speeds up the referral process, improves both diagnosis and the clinical decision process, and on average reduces by one or two days the length-of-stay for patients in hospitals. From their office workstations, cardiologists are able to consult the advanced clinical images provided by any hospital linked to the network. The distributed storage of records eliminates the duplication of records across multiple sites. Once uploaded to the cardiology network, records remain available for consultation at any time so that previous episodes of a patient’s care can be consulted in detail no matter where the care was provided in the region.
HPHC is a non-profit insurance provider which serves members throughout Massachusetts, New Hampshire, and Maine. The provider offers variety health insurance options for companies, families and individuals. Customers health insurance expectations are met through a tailored options from preferred provider organization (PPO), point-of-sale (POS), and health maintenance organization (HMO). HPHC implements CRM, Master Data Management and is now implementing Oracle Policy Automation to support integrated call center and online self-service for plan purchase and management across their various customer groups additionally, HPHC is using their platform to support recruitment and to better analyze and improve service levels in a heavily competitive market.
The Indiana Health Information Exchange (IHIE) operates the U.S.'s largest HIE and one of the oldest with data on more than 7 million patients, connecting hospitals, rehabilitation centers, long term care facilities, laboratories, imaging centers, clinics, community health centers and other healthcare organizations. Created and ran by the Regenstrief Institute, a medical informatics think tank, the Indiana Network for Patient Care (INPC), a secure network provides a patient records to participating doctors. The IHIE provides current data about admissions, discharges, and transfers to help health plans and accountable care organizations reduce nonurgent emergency department visits. This HIE grew over time from 12 hospitals in the center of the state with approximately 5,000 physicians, to 93 hospitals out of 114 in the state and more than 14,000 physicians in Indiana.
MHIN is one of the first HIEs in the United States and offers unprecedented levels of integration and connectivity to healthcare professionals and providers. In 1998, MHIN was incorporated, and the team went right to work improving, securing, and facilitating communication among providers. Today, MHIN continues to assist communities throughout the Midwest to establish a regionally based HIE. Organizations across the healthcare spectrum - from hospitals to specialty groups to medical labs and diagnostic centers - find solutions in MHIN's diverse service platform. MHIN's core applications provide an efficient, secure way for providers to exchange information and facilitate high-quality, coordinated care.
Michigan Health Connect (MHC) is a Regional Health Information Organization (RHIO) that facilitates and manages Health Information Exchange (HIE) services in the State of Michigan. MHC was founded in 2009 when 3 independent health systems in West Michigan (Spectrum Health, Trinity Health, and Metro Health) realized they had licensed the same vendor’s clinical messaging technology and had plans to deploy that technology to many of the same community provider organizations. Agreeing to collaborate and not compete on clinical data exchange, the health systems began meeting to determine what they could do together in conjunction with their vendor, Medicity. In the subsequent weeks, both Lakeland Health System and Northern Michigan Regional Health System were added to the collaborative discussions, each also independently licensing Medicity’s clinical messaging platform. After collaborating for many months and with good progress and momentum developed related to common robust health information exchange in their respective communities, in March of 2010 MHC was formally launched as a charitable [509(a)2] non-profit corporation in Michigan.
The Utah Health Information Network (UHIN) is a broad-based coalition of Utah healthcare insurers, providers, and other interested parties, including the Utah State government. Since 1993, UHIN members have come together for the common goal of reducing healthcare costs and improving the quality of care through the use of electronic data interchange (EDI) for healthcare transactions. Exchanging information electronically rather than by phone, fax or surface mail means that data can get to those who need it securely, economically and efficiently. UHIN currently serves nearly all the hospitals, ambulatory surgery centers, national laboratories, insurers, and approximately 90% of the medical providers in Utah as well as the Utah State government. As a community organization the focus is on creating data exchange solutions that work for the entire healthcare community, from large integrated networks to single-provider offices. The Clinical Health Information Exchange (cHIE) is a secure electronic way for medical professionals to share and view patient information that is needed at the point of care. The cHIE makes this information accessible, with patient consent, to authorized users while maintaining the highest standards of patient privacy.
DICOM (Digital Imaging and Communications in Medicine)
LOINC (Logical Observation Identifiers Names and Codes)