Descriptive epidemiology of hereditary angioedema emergency department visits in the United States, 2006-2007.

Hereditary angioedema (HAE) is a rare inherited disorder of complement factor C1 inhibitor. In 2007 there were over 2000 HAE-related emergency department (ED) visits, nearly one-half of which culminated in a hospitalization. This study examines epidemiology and outcomes of hospital ED visits among HAE patients. We evaluated epidemiology, resource use, and discharge destinations of HAE (International Classification of Diseases, Version 9, clinical modification [ICD-9-CM] code 277.6) ED visits within the Nationwide Emergency Department Sample, part of Agency for Healthcare Research and Quality Healthcare Costs and Utilization Project, in 2006 and 2007. In 2006-2007, there were 5040 ED visits with HAE, of which 2705 (53.7%) had HAE as the principal diagnosis (HAE-PD). The mean age for all HAE visits was 38.2 years, and women accounted for 56.5% of all HAE visits. When HAE was not the primary reason for the visit, abdominal pain was the most prevalent (10%) presenting diagnosis. Two thousand fifty-nine (40.9%) resulted in a hospitalization. Although of all HAE ED visits that did not require a hospitalization, the vast majority was discharged routinely home, further care either at a skilled nursing facility or at home was required after 45 (0.9%) of all the HAE visits and 10 (0.4%) of the HAE-PD visits. Mean HAE ED visits costs were $1479 (95% confidence interval, $1028-1929). HAE ED visit volume is substantial. Although likely representing a fraction of the entire HAE population, prevention and acute treatment strategies aimed at those at risk for frequent exacerbations and disproportionate resource use need to be examined.