ATCEMS Performance Dashboard > Stroke Alert Scene Time > Performance Measure Definition: Stroke Alert Scene Time
Performance Measure Definition: Stroke Alert Scene Time

Description: This indicator measures how long ATCEMS units remain on scene, assessing and treating patients who meet Stroke Alert criteria. It fulfills the specifications for CPI 2.5 from the ATCEMS System Office of the Medical Director (OMD).
Desired Outcome: ATCEMS crews rapidly identify patients meeting Stroke Alert criteria and then minimize time spent on scene, quickly beginning transport to an appropriate Stroke Center.
Relevance: Stroke Alert patients require rapid access to definitive care for their condition. In these cases, ATCEMS personnel must prioritize initiation of transport over non-lifesaving care.
Measure Domain: Clinical Care
Type of Measure: Process

Operational Specifications
Formula Description: Arrange the scene time interval data points (for the quarter) from lowest to highest. Count the total number of data points and note the number as N. Multiply 0.90 by the number N (round up if needed) and note as P. Determine the P-th data point in the set counting form the lowest to the highest value. That data point is the 90th percentile scene time interval. This may be accomplished using MS Excel’s percentile function.
Unit of Analysis: Patient Contact
  • Numerator: All patients meeting Stroke Alert criteria who are transported to a receiving facility.
  • Denominator: Not applicable.
Measure Frequency: Quarterly
Minimum Population/Sample: 20 contacts
Performance Standard: Maintain a 90th percentile scene interval of less than 15 minutes every quarter.
Acceptable Quality Level: Not defined
Interval Description: The time interval beginning with the Scene Arrival Time for the first on scene transporting unit and ending with the Scene Departure time (from CAD) for the unit transporting the patient.
Reporting Value: 90th percentile scene time, i.e. the time interval (in mm:ss) for which 90% of the incident scene time intervals are less than or equal.
  • Time-based aggregations (month, quarter, etc.) are based on [Time – Phone Pickup].
  • Geographic aggregations are based on incident location.
Stratification: None
Limitations: A population of less than 20 patients may result in calculation errors.
Related Measures:
  • Stroke Alert Scene Time Compliance: The compliance indicator uses the same filter set as the CPI measure, but reports performance as a percentage of patient contacts meeting performance goal. This format supports inclusion in and support of Stroke Alert Bundle reporting.
Notes: Transport delays may be unavoidable in some cases, such as delayed access to patients due to scene safety issues, difficulty identifying or reaching patient, etc. These cases are excluded from measure calculation.
Performance is reported on a quarterly basis due to generally small monthly patient counts.

ATCEMS Open Performance Dashboard
City of Austin Open Data Portal

Office of the Medical Director, Austin/Travis County EMS System (2014). “Clinical Performance Indicator 2.5: Scene Time Interval for Stroke Alert Patients.”
Office of the Medical Director, Austin/Travis County EMS System (2016). “Clinical Standard CS-34: Stroke Alert Criteria.” Austin-Travis County Emergency Medical Service System Clinical Operating Guidelines version 021716.

Development Status: Actively reporting
Definition Version: Version A
Revision Date: 2017-01-24
Revised By: David Andersen