282 Impact of Emergency Medical Services Vehicle Use by Acute Ischemic Stroke Patients on Functional Outcomes: An Observational Study

Abstract

Previous studies have documented the impact of emergency medical services (EMS) vehicle use on speedy thrombolytic treatment, but not on patient functional outcomes. We assessed the association of EMS use with likelihood and timeliness of intravenous (IV) thrombolytic treatment and functional outcomes at discharge and 90 days. Prospective observational study using Get With The Guidelines Stroke data on AIS patients with cerebrovascular imaging evidence, discharged 4/2016 to 10/2017 from a non-profit hospital’s primary stroke center unit in Columbia, South Carolina. Key outcomes of interest were: National Institutes of Health Stroke Scale (NIHSS) change from arrival to discharge (continuous variable), discharge disposition (discharged to home versus otherwise), and 90-day modified Rankin Scale, mRS 0-1 versus otherwise, (ascertained by phone calls to patients discharged from 4/2018 to 8/2017 within 75-105 days of discharge using a standardized script, supplemented by medical record data on neurology follow-up visits). Multiple logistic and linear regression analyses were used as appropriate. Of 1,166 total AIS discharges, 328 were excluded (transfer patients or hospice assigned pre-admission). Among 838 study-eligible patients, 52.4% were black, 72.2% arrived by EMS, mean admission NIHSS (available for 96.7% of patients) was 6.8 (±7.3; median 4.0, range 0 - 37), mean stroke-relevant comorbidities per patient 3.7 (±1.9), alteplase received 114 (13.6%), and 92 expired or assigned to hospice. Mean door to imaging (DTI) time was 98.8 minutes (±151.0; median 49), and mean door to needle (DTN) time for IV alteplase recipients, 46.2 minutes (±31.2; median 38.0). In bivariate analyses, EMS arrivals were older (mean age 70 years versus 63.6 for other transport), more severe (mean NIHSS 8.3 (±7.7) versus 2.9 (±3.7), more likely to have contraindications to alteplase, and had worse discharge outcomes. Adjusted for demographic and other factors, EMS use was highly associated with stroke severity (adjusted odds 4.1 for moderate stroke (NIHSS 6-15) versus mild stroke (NIHSS 0-5), and 12.3 for severe stroke (NIHSS>15), p<0.001). Adjusted for stroke severity, comorbidities, endovascular treatment and other relevant factors as appropriate, EMS arrival (relative to other transport) was associated with: 5-fold higher odds of IV alteplase, 88.5 minutes lower DTI (p<0.01; 57% reduction), and, among severe stroke patients, 5.7 points better improvement in discharge NHISS over admission NIHSS (all p<0.001). Insurance status and race were not significant factors in alteplase use, DTI or DTN. Discharge disposition was not significantly associated with arrival mode. 90-day mRS was ascertained for 430 patients (59.2% of eligible, despite 87.1% of eligibles fully pursued per protocol). The study lacked statistical power to assess EMS impact on 90-day mRS, given the effect magnitude of stroke severity on both EMS use and 90-day outcomes. However, discharge NIHSS accurately predicted 90-day mRS, (adjusted beta 0.20; score ranges of the 2 scales, 0-37 versus 0-6; model R2 = 0.42), supporting that EMS use may produce better long-term outcomes in severe stroke patients. This study breaks new ground, documenting a positive impact of EMS use on functional outcomes in severe stroke. Given evidence of equitable care regardless of insurance status/race at the study center, findings may be generalizable despite being a single-center observational study.