Emergency Department Visits Attributable to Asthma in North Carolina, 2008

Abstract

A sthma is a prevalent chronic disease that is associated with substantial morbidity, health care utilization, and cost [1][2][3]. Both the US Department of Health and Human Services and the Centers for Disease Control and Prevention recognize that surveillance of population-level trends in prevalence, health care utilization, and morbidity can support efforts to plan for and reduce the consequences of asthma [3][4][5]. Currently, national estimates of asthma prevalence and health care utilization allow comparisons across states and regions [6][7][8] but cannot be used by states to support more targeted efforts to reduce the burden of asthma.The North Carolina Disease Event Tracking and Epidemiologic Collection Tool (NC DETECT) collects statewide population data on all emergency department (ED) visits [9,10]. ED visits are critical to asthma surveillance, because they may identify preventable asthma exacerbations and because they may be the occasion for implementation of evidence-based public health interventions that can support state and local efforts to improve asthma control [11][12][13]. Using 2008 NC DETECT data, we examine statewide patterns of ED use in North Carolina for asthma, both overall and by age, sex, geography, insurance status, and month (seasonality). We also identify patterns of frequent use of the ED for asthma treatment. Methods Data SourcesWe used NC DETECT [10] to identify all visits to civilian, acute care, hospital-affiliated EDs in North Carolina made by residents of the state during 2008. While analysis focuses on ED visits made by NC residents during 2008, additional NC DETECT data was used to identify additional ED visits made by the patients between December 1, 2007 and December 31, 2009. NC DETECT received data for an estimated 99.5% of all ED visits in the state that year. We used county-level population estimates for 2008 from the North Carolina Office of State Budget and Management [14]. Our estimate of the percentage of North Carolina residents who were uninsured in 2008 comes from Current Population Survey data [15]. MeasuresAsthma ED visits. We defined asthma ED visits as visits with an ICD-9-CM code of asthma (493.xx) as the first or second diagnosis, a strategy supported by our analysis of NC DETECT visit data (abstract under review). With the NC DETECT data, we were able to link visits made by an individual to the same facility, but not visits made by an individual to different facilities, because there is no common patient identifier used by all facilities. We began by prospectively counting the number of asthma ED visits made by each patient to the same facility during the 365 days following his