@article {Locker398, author = {Thomas E Locker and Simon Baston and Suzanne M Mason and Jon Nicholl}, title = {Defining frequent use of an urban emergency department}, volume = {24}, number = {6}, pages = {398--401}, year = {2007}, doi = {10.1136/emj.2006.043844}, publisher = {British Association for Accident and Emergency Medicine}, abstract = {Objective: This study aimed to develop a definition of frequent use of an emergency department (ED) by comparing differences in the observed frequency distribution with that of a theoretical frequency distribution. Methods: A retrospective analysis of attendance of ED and minor injury unit attendances in one city over 1 year was conducted. From these data, the expected frequency distribution was determined based upon a Poisson distribution. Results: During the period studied, 75 141 people attended on 98 908 occasions. The theoretical frequency distribution showed that there were 2764 (3.7\%) {\textquotedblleft}frequent users{\textquotedblright} presenting repeatedly due to non-random events. These patients made 12 316 (12.4\%) attendances. Frequent users were older than chance users (mean age 49.7 vs 44.5 years). A greater proportion arrived by ambulance (55.3\% vs 27.5\%), presented with psychiatric problems (5.8\% vs 1.1\%) or alcohol intoxication (1.3\% vs 0.5\%), and were admitted to hospital (37.4\% vs 19.6\%). Conclusion: We have identified that there is a group of patients who present repeatedly due to non-random events, confirming the existence of {\textquotedblleft}frequent users{\textquotedblright}. Their characteristics are clearly different to other patients in the ED. We propose that {\textquotedblleft}frequent users{\textquotedblright} be defined as any patient who makes more than four attendances per year.}, issn = {1472-0205}, URL = {https://emj.bmj.com/content/24/6/398}, eprint = {https://emj.bmj.com/content/24/6/398.full.pdf}, journal = {Emergency Medicine Journal} }