Access to primary health care is a problem for many patients in the U.S., leading many to seek care through the emergency department (ED). While the majority of ED visits are appropriate, many may be “prevented” by timely and potentially less costly ambulatory care. Several systems of estimating potentially avoidable ED visits have therefore been developed, including the NYU/Billings ED algorithm. Many health care organizations use these tools in actuarial risk stratification and individually oriented interventions to improve patient outcomes and lower costs.