DOI: 10.5811/westjem.2013.8.19100

Recently policymakers, payers, and the media have focused attention on avoiding ‘inappropriate ’ or ‘unnecessary’ emergency department visits.1 Some states and payers have tried to institute co-pays or deny coverage for visits deemed to be non urgent with the goal of decreasing unnecessary emergency department (ED) visits.2,3 The discussion is predicated upon the ‘common knowledge ’ that by diverting unnecessary ED visits, substantial healthcare spending will be avoided. This ‘common knowledge ’ is wrong. Many of the frequently used methodologies to classify ED visits are based on the NYU ED algorithm, developed in the late 1990s to classify ED use.4 Using expert opinion, charts were reviewed to determine if a particular visit was urgent. The algorithm was constructed to generate a probability that a particular discharge diagnosis results from a non-emergen