Background: The benefit of tissue plasminogen activator (tPA) in the treatment of acute ischemic stroke is time-dependent. AHA/ASA guidelines recommend a goal door-to-needle (DTN) time of 60 minutes or less. In practice, medically complicated patients can pose challenges leading to prolonged treatment times that skew institutional mean DTN values. We aimed to produce a simple statistical tool to calculate individualized DTN targets while accounting for outliers to help institutions achieve a mean DTN < 60 minutes.
Methods: An IRB approved, single-center, retrospective analysis of consecutive acute stroke code case data from Duke University Hospital (Durham, NC) between January 2014 and July 2016 was conducted. We devised a formula (Figure 1) to calculate the goal DTN time (tg) necessary to achieve an overall mean DTN of < 60 minutes while adjusting for the frequency and magnitude of outliers. This formula was created as a modifiable tool using an individual institution’s outlier definition, current outlier frequency (fm), and outlier DTN average (tm) over a pre-defined time period. As proof of concept, the formula was tested using an outlier definition of ≥100 minutes. The formula was modeled using both real-world institutional data and a simulated sample of 200 patients.
Results: In 1069 consecutive stroke codes, tPA was administered in 135 cases with mean DTN 68.2 minutes (range 15-205). Of these, 18 cases (13.3%) met our definition of outlier, with tm of 134 minutes. Using the developed formula with institutional data resulted in a target DTN of 48.6 minutes for non-outlier cases to achieve overall mean DTN < 60 minutes. Using the simulated dataset, our tool similarly calculated a goal DTN of 49 minutes.
Conclusions: This simple statistical tool is a novel solution for generating an institution-specific goal DTN based on unique organizational data, experiences, and nuances in order to meet the recommended mean DTN. Additionally, these individualized goals may further motivate stroke teams to carry out more efficient clinical care rather than consistently aiming for DTN values < 60 minutes. The tool presented here is easily adaptable to future changes in recommended target goals and can be seamlessly incorporated into institution-wide systems planning.