EMS World

DEC 2018

EMS World Magazine is the most authoritative source in the world for clinical and educational material designed to improve the delivery of prehospital emergency medical care.

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THE TRIP REPORT: TURNING RESEARCH INTO PRACTICE 18 DECEMBER 2018 | EMSWORLD.com was rigorous in that they not only evaluated the impact of this time interval on mortality, but they adjusted their results for potential confounding variables. Specifically they used multivariable logis- tic regression modeling to adjust for patient age, sex, initial blood pressure, presence of cardiogenic shock, prior history of MI, and risk level. Risk level was categorized as high or low. High-risk patients were at least 70 years of age, presented in cardiogenic shock, and had an initial blood pressure of less than 100 mmHg or a prior history of MI. Results There were 551 patients enrolled in this study. There were 8.0% of patients with confirmed mortality at one year and 5.1% at one month. Average time from 9-1-1 call to PCI was 81.8 minutes. Patients who died had a significantly longer time to PCI when compared to those who survived. For those who died the time from 9-1-1 call to PCI was 93.6 minutes, with a 95% confidence interval of 88.1–99.7 minutes. Those who survived had a 9-1-1-to-PCI time of 80.8 minutes, with a 95% confidence interval of 79.1–82.5 minutes. This difference was statistically significant, with a p-value less than 0.001. Patients who died were also older (67.8 vs. 59.1 years) and more likely to be classified in the high-risk category (11.0% vs. 4.4%). In the multivariable logistic regression model, the only confounding variable that remained after adjustment was age. The model revealed that for every one-minute increase in the time between the 9-1-1 call and PCI, the odds of survival at one year deceased by 3% (OR 0.97; 95% CI, 0.96–0.99). Results were similar for patient mortality at one month (OR 0.97; 95% CI, 0.95–0.98). This study identified an important metric that can be used as an effective predictor of mortality. But while this metric can be con- sistently and reliably recorded and assessed, simply measuring the time from 9-1-1 to PCI is not sufficient. The authors importantly emphasized the need for coordination in a STEMI system of care. Specifically they said, "PCI centers interested in decreasing mortal- ity must engage their EMS systems to devel- op a comprehensive approach to STEMI care. EMS systems interested in achieving their mission of providing emergency care to patients when and where they are needed should engage with their PCI centers and measure their system performance as it relates to STEMI patients." Limitations The authors here did a good job in detail- ing their study's limitations. Again, this is a mature system with a highly integrated STEMI system of care, so these results may not be generalizable. The authors also noted that patients may have been excluded from the study because they were not classified as STEMI patients in the prehospital setting. They also may have misclassified patients as survivors if they didn't have a follow-up visit or a death certificate was not identified. Finally, the authors noted they may have introduced selection bias by only including patients who received primary PCI. These limitations are common with this research design. The authors took multiple steps to reduce bias, and the system design certainly reduced the impact of these limitations. ABOUT THE AUTHOR Antonio R. Fernandez, PhD, NRP, FAHA, is research director at the EMS Performance Improvement Center and an assistant professor in the Department of Emergency Medicine at the University of North Carolina–Chapel Hill.

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