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- Title
Accuracy of Prehospital Transport Time Estimation La Precisión de la Estimación del Tiempo de Traslado Extrahospitalario.
- Authors
Wallace, David J.; Kahn, Jeremy M.; Angus, Derek C.; Martin‐Gill, Christian; Callaway, Clifton W.; Rea, Thomas D.; Chhatwal, Jagpreet; Kurland, Kristen; Seymour, Christopher W.; Meisel, Zachary F.
- Abstract
Objectives Estimates of prehospital transport times are an important part of emergency care system research and planning; however, the accuracy of these estimates is unknown. The authors examined the accuracy of three estimation methods against observed transport times in a large cohort of prehospital patient transports. Methods This was a validation study using prehospital records in King County, Washington, and southwestern Pennsylvania from 2002 to 2006 and 2005 to 2011, respectively. Transport time estimates were generated using three methods: linear arc distance, Google Maps, and Arc GIS Network Analyst. Estimation error, defined as the absolute difference between observed and estimated transport time, was assessed, as well as the proportion of estimated times that were within specified error thresholds. Based on the primary results, a regression estimate was used that incorporated population density, time of day, and season to assess improved accuracy. Finally, hospital catchment areas were compared using each method with a fixed drive time. Results The authors analyzed 29,935 prehospital transports to 44 hospitals. The mean (± standard deviation [± SD]) absolute error was 4.8 (±7.3) minutes using linear arc, 3.5 (±5.4) minutes using Google Maps, and 4.4 (±5.7) minutes using Arc GIS. All pairwise comparisons were statistically significant (p < 0.01). Estimation accuracy was lower for each method among transports more than 20 minutes (mean [± SD] absolute error was 12.7 [±11.7] minutes for linear arc, 9.8 [±10.5] minutes for Google Maps, and 11.6 [±10.9] minutes for Arc GIS). Estimates were within 5 minutes of observed transport time for 79% of linear arc estimates, 86.6% of Google Maps estimates, and 81.3% of Arc GIS estimates. The regression-based approach did not substantially improve estimation. There were large differences in hospital catchment areas estimated by each method. Conclusions Route-based transport time estimates demonstrate moderate accuracy. These methods can be valuable for informing a host of decisions related to the system organization and patient access to emergency medical care; however, they should be employed with sensitivity to their limitations.
- Subjects
DIAGNOSIS methods; DEMOGRAPHY; EMERGENCY medicine; RESEARCH methodology; STATISTICS; T-test (Statistics); TIME management; DATA analysis; TRANSPORTATION of patients; DATA analysis software
- Publication
Academic Emergency Medicine, 2014, Vol 21, Issue 1, p9
- ISSN
1069-6563
- Publication type
Article
- DOI
10.1111/acem.12289