i2b2 enables researchers to discover cohorts of patients using data from EHR systems.  Through a point-and-click interface, researchers can build queries drawing from demographics, diagnoses, procedures, medications, and results recorded in Epic, the EHR system of Weill Cornell Physician Organization outpatient clinics (access to data from Eclipsys/Allscripts Sunrise Clinical Manager, the EHR system of NewYork-Presbyterian inpatient units, is planned).  i2b2 supports different types of queries of clinical data, including whether clinical concepts occurred at any point in a patient’s medical history, during a particular visit, or in a sequence of events.  Using de-identified data, investigators can determine potential cohorts of interest for later obtaining identified or limited data sets with Institutional Review Board (IRB) approval