Abstract 69: A Time Series Analysis of Cardiac Arrest Incidence in Denver, Colorado

Abstract

Background: Out-of-hospital cardiac arrest (OHCA) is estimated to cause 250,000 deaths annually in the U.S. Previous research has shown seasonal variation in cardiac arrest incidence. However, little is known about how cardiac arrest varies in Denver, CO across time. Objectives: To analyze cardiac arrest incidence in Denver for 2009-2012 to assess for trends in incidence, seasonal variation and predict future cardiac arrest incidence. Methods: Design: Secondary analysis of the Denver, Colorado component of the Cardiac Arrest Registry to Enhance Survival (CARES) dataset. Setting: Large urban metropolitan community with a two-tiered EMS system. The catchment area for this community is approximately 150 square miles with an approximate residential census of 600,000 people and includes 10 adult acute-care receiving hospitals. Population: Consecutive arrests from January 15, 2009 through March 31, 2012 entered by Denver Health Paramedic Division staff into the CARES dataset. Data Analysis: Arrests were grouped by month using Stata. R software was used to estimate the trend, seasonality and random error associated with events. An ARIMA model was used to fit the data and predict future OHCA incidence for the subsequent 24 months. Results: There were a total of 2,270 cardiac arrests patients during the 39 months. Overall, there appears to be a decreasing trend in the incidence of cardiac arrest in Denver (Figure 1). There does also appear to be seasonality in cardiac arrest events. The maximum number of arrests occurred in October 2010 (97). An ARIMA Model (0,2,2) was used to predict future cardiac arrest occurrence over the next 24 months. Conclusion: It is possible that wide-scale cardiac arrest and prevention efforts have contributed to the decreasing trend in OHCA incidence. Future research will need to examine what factors (e.g., season, temperature, etc.) may be contributing to the observed seasonal variation pattern.