by default and generally must submit a written request to join the 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. List of European health information exchanges The Netherlands Frysian Health Information Exchange Connects Medical Centre Leeuwarden and Academic Center in Groningen with community hospitals like Nij Smellinghe Hospital in Drachten. The Friesland Regional Cardiology Network speeds up the referral process, improves both diagnosis and the clinical decision process. On average, it reduces the length-of-stay for patients in hospitals by one or two days. 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. North of the Netherlands – XDS Network Hospitals in the Dutch provinces Groningen, Friesland and Drenthe have created an (diagnostic) image exchange network in order to phase out CD/DVD based exchanges using an IHE (XDS) platform. St. Gerrit, the local HIE organization, has gradually expanded the network since 2014, spanning 10 hospitals to date. Diagnostic images and related reports are exchanged to support a number of use-cases including radiology referrals to the Academic Medical Center Groningen (UMCG), radiotherapy treatments, CVA Stroke Traumas and proton therapy. The HIE network has developed a number of cross-enterprise workflows using IHE XDW. Other Dutch HIEs ZorgNetOost Radboud University Medical Center Jeroen Bosch Ziekenhuis Limburg Exchange Network – Maastricht University Medical Center, Maastro Radiation Therapy Institute, Laurentius Hospital Image Exchange South East-Brabant – Maxima Medical Center, Elkerliek Hospital, Catharina Hospital Eindhoven, St. Anna Hospital Regional Exchange Network West-Brabant Image Exchange Network Breda – Amphia Hospital, BVI, Elisabeth-TweeSteden Hospital Rotterdam Exchange Network RijnmondNet TRIJN Zorgring Noord-Holland Noord United Kingdom Sussex and Surrey Bristol Great Ormond Street Hospital Ireland NIMIS Finland Helsinki-Uusimaa Health district List of United States health information exchanges Individual exchanges Chesapeake