Spatial patterns of epilepsy-related emergency department visits in california

Socio-demographic factors are associated with increased emergency department (ED) use among patients with epilepsy. However, there has been limited spatial analysis of such visits.

California ED visit at the patient ZIP Code level were examined using Kulldorf's spatial scan statistic to identify clusters of increased risk for epilepsy-related visits. Logistic regression was used to examine the relative importance of patient socio-demographics, Census-based and hospital measures.

During 2009-2011 there were 29,715,009 ED visits at 330 hospitals, of which 139,235 (0.5%) had epilepsy (International Classification of Disease-9 345.xx) as the primary diagnosis. Three large urban clusters of high epilepsy-related ED visits were centred in the cities of Los Angeles, Oakland and Stockton and a large rural cluster centred in Kern County. No consistent pattern by age, race/ethnicity, household structure, and income was observed among all clusters. Regression found only the Los Angeles cluster significant after adjusting for other measures.

Geospatial analysis within a large and geographically diverse region identified a cluster within its most populous city having an increased risk of ED visits for epilepsy independent of selected socio-demographic and hospital measures. Additional research is necessary to determine whether elevated rates of ED visits represent increased prevalence of epilepsy or an inequitable system of epilepsy care. Significance for public healthThere have been few spatial analyses regarding treatment for epilepsy. This paper significantly expands upon previous work by simultaneously considering multiple urban centres and sparsely populated agricultural and desert/mountain areas in a large state. Furthermore, most epilepsy studies involve one system of care or funding source (such as Department of Veterans Affairs, Medicare, Medicaid, or private insurance plans). This paper considers all funding sources at community-based hospitals. Patient socio-demographics, area-based summaries of socio-demographics, and basic hospital characteristics explain most of the observed spatial variation in rates of emergency department (ED) visits related to epilepsy. However, preliminary spatial analysis demonstrated that an area within downtown Los Angeles did have a higher rate of epilepsy-related visits compared to the rest of the state. A more comprehensive surveillance approach with ED visit data could be readily applied to other large geographic areas and be useful both for on-going monitoring and public health intervention.