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Comparative Study
. 2014 May;45(5):1275-9.
doi: 10.1161/STROKEAHA.113.003955. Epub 2014 Mar 18.

Accuracy of emergency medical services-reported last known normal times in patients suspected with acute stroke

David Curfman  1 , Lisa Tabor Connor, Hawnwan Philip Moy, Laura Heitsch, Peter Panagos, Jin-Moo Lee, David K Tan, Andria L Ford
Affiliations
Comparative Study

Accuracy of emergency medical services-reported last known normal times in patients suspected with acute stroke

David Curfman et al. Stroke. 2014 May.

Abstract

Background and purpose: The last known normal (LKN) time is a critical determinant of IV tissue-type plasminogen activator (IV tPA) eligibility; however, the accuracy of emergency medical services (EMS)-reported LKN times is unknown. We determined the congruence between neurologist-determined and EMS-reported LKN times and identified predictors of incongruent LKN times.

Methods: We prospectively collected EMS-reported LKN times for patients brought into the emergency department with suspected acute stroke and calculated the absolute difference between the neurologist-determined and EMS-reported LKN times (|ΔLKN|). We determined the rate of inappropriate IV tPA use if EMS-reported times had been used in place of neurologist-determined times. Univariate and multivariable linear regression assessed for any predictors of prolonged |ΔLKN|.

Results: Of 251 patients, mean and median |ΔLKN| were 28 and 0 minutes, respectively. |ΔLKN| was <15 minutes in 91% of the entire cohort and <15 minutes in 80% of patients with a diagnosis of stroke (n=86). Of patients who received IV tPA, none would have been incorrectly excluded from IV tPA if the EMS LKN time had been used. Conversely, of patients who did not receive IV tPA, 6% would have been incorrectly included for IV tPA consideration had the EMS time been used. In patients with wake-up stroke symptoms, EMS underestimated LKN times: mean neurologist LKN time-EMS LKN time=208 minutes. The presence of wake-up stroke symptoms (P<0.0001) and older age (P=0.019) were independent predictors of prolonged |ΔLKN|.

Conclusions: EMS-reported LKN times were largely congruent with neurologist-determined times. Focused EMS training regarding wake-up stroke symptoms may further improve accuracy.

Keywords: Emergency Medical Services; last known normal time; stroke.

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Figures

Figure
Figure
Frequency histograms for the differences in EMS-reported and neurologist-determined LKN times (ΔLKN) for: (A) patients with an ED diagnosis of Stroke (gray) compared to Non-Stroke (black) and (B) patients without wake-up stroke symptoms (gray) and with wake-up stroke symptoms (black).
See this image and copyright information in PMC

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