Abstract 157: Increased Rates of Intravenous Thrombolysis for Acute Stroke in California Correlate with Expansion of Acute Stroke EMS Routing Protocols, 2006-2010

Abstract

Background: Primary stroke centers (PSCs) have been observed to have better stroke outcomes, and to have higher IV intravenous tissue-type plasminogen activator (IV tPA) utilization rates. Emergency medical services (EMS) began using routing protocols to direct suspected acute stroke patients to PSCs in the first decade of the century. We sought to determine the impact of county-level EMS stroke routing protocols on IV tPA utilization rates in California (CA). Methods: We extracted county-level patient discharge data from Office of Statewide Health Planning and Development database, an all-payer database including all hospitalizations in CA from 2006-2010. We used Diagnosis Related Group codes to identify all patients hospitalized for stroke, and patients who received a thrombolytic agent for stroke. We contacted EMS departments in CA and worked with the American Heart Association to determine which counties were utilizing EMS routing protocols and the year implemented. Using chi-square, we compared tPA usage in routing counties vs. non-routing counties. Among counties that implemented routing protocols, we compared tPA usage 1 year pre- and post-routing protocol implementation. Results: Of 58 counties in CA, 19 were identified to have implemented acute stroke EMS routing protocols in years 2006 and 2010. Across this 5 year period, use of tPA among counties without a concurrent EMS routing protocol was 2.1% [1663/79148], whereas use of tPA among counties with a concurrent EMS routing protocol was 3.1% [4853/154962] (p<0.001). Among the 39 counties that have not yet implemented EMS routing protocols, tPA use increased from 1.3% to 3.1% from 2006-2010. In the same time period, the 19 counties with EMS routing protocols showed tPA use increased from 2.3% to 4.4%. Further analysis was performed for counties whose data for tPA usage 1 year pre- and post-routing were available: San Francisco County (2007); Alameda, Kern, San Mateo Counties (2008); Los Angeles, Orange, Sacramento, San Diego Counties (2009). Counties that implemented EMS acute stroke routing protocols increased tPA rates usage from 2.6% in the year before routing to 4.0% in the year after routing (p<0.001). Conclusions: Counties with EMS protocols to route acute stroke patients to PSCs have higher IV tPA rates than non-routing counties. Routing counties are also seen to increase their rate of IV tPA after beginning implementation of routing protocols. To continue to improve acute stroke care through the usage of IV tPA, current non-routing counties should consider implementing routing protocols to transport acute stroke patients to PSCs.