Electronic Medical Records-EMR has been an increasingly major area of research in order to improve quality of health services, by reducing attention time, probability of errors and helping all the actors in the ecosystem for accountability and traceability. However, patients are probably one of the actors that, despite being the main actor to be protected by regulations, have the least access to its information and control over what, who, when, how and why other actors in the healthcare system are doing with their information, especially in cases where just the existence of some tests may reveal an illness or a condition that should remain private. There is existing work and regulations on defining user-centered access control to the data, but the options are usually focused on defining policies on who has access to the information. This work introduces an incremental data access options in order to increase privacy over the data by considering the possibility of offering slightly altered or obfuscated data as an option to protect the original information, revealing just enough to enable the desired services. A differential privacy classification of access is presented, tested on lab data and evaluated, showing that different levels of privacy protection can be used in certain cases and for a limited number of services, while preserving privacy of the data. In addition, this technique can be integrated with other access-control techniques in literature.
