Abstract TMP66: Eight-year Trends in Ambulance Use in a National Sample of Medicare Beneficiaries With Stroke

Abstract

Thrombolysis for acute stroke must be administered within a short time after stroke onset. Since ambulance use has been shown to ensure timely arrival leading to higher use of thrombolysis, we evaluated the trend in ambulance use among all Medicare beneficiaries with stroke and compared the utilization of ambulance transport among subgroups of patients. Method: The study analyzed the first hospitalization of aged 66+ patients where the primary diagnosis was ischemic stroke from Medicare claims (2007-2014). We excluded patients without continuous enrollment in Parts A+B in the year prior to stroke hospitalization. The primary outcome measure was ambulance arrival among stroke patients who were treated in the emergency department. Ambulance transport was identified from Medicare carrier and outpatient claims (HCPCS A0425-A0436). We calculated Cochran-Armitage trend tests to assess changes in utilization over time and chi-square tests to compare utilization by patient and hospital characteristics. Results: Among 240,486 patients, the ambulation utilization rate increased from 61.2% in 2007 to 63.5% in 2014 (p<0.001). Small but significant increasing trends were observed among most age, racial, and area subgroups, but was not observed among Hispanic patients. Patient and hospital characteristics were associated with the ambulance utilization (all p 0.002). Older patients were much more likely to arrive by ambulance (age 86+ 72.4%, 76-85 62.1%, 66-75 52.4%, Figure). Higher utilization rates were also observed for Non-Hispanic White patients (63.1%, Hispanic 58.5%, Black 57.6%, Asian 54.3%) and patients in rural areas (63.1%, urban 62.1%). Conclusion: Although ambulance use has increased, more than one-third of Medicare beneficiaries with stroke use other forms of transportation. In this ongoing multi-year study, we will assess thrombolysis use by transport modality and estimate the impact of prehospital care on thrombolysis and functional outcomes.