Estimating the effect of emergency care on early survival after traffic crashes

David E. Clark, Robert J. Winchell, Rebecca Betensky

Research output: Contribution to journalArticle

Abstract

Introduction Traffic crash mortality is higher in rural areas, but it is unclear whether this is due to greater injury severity, time delays, or Emergency Medical Services (EMS) deficiencies. Methods Data from 2002-2003 were combined from the Fatality Analysis Reporting System (FARS) and an "expanded version" of the National Automotive Sampling System (NASS) Crashworthiness Data System (CDS). Weighted Cox and Weibull models for survival time (tSURV) were estimated, with time-varying covariates (TVC) having constant effects for specified time intervals following EMS arrival time (tEMS) and hospital arrival time (tHOS). The Weibull model was repeated with tSURV interval-censored to reflect uncertainty about the exact time of death, using an imputation method to accommodate interval censoring along with TVC. Results FARS contained records for 92,718 persons with fatal or incapacitating injuries, and NASS/CDS contained 5517 (weighted population of 642,716) with incapacitating injuries. All models associated mortality with increasing age, male sex, belt nonuse, higher speeds, and vehicle rollover. The interval-censored model associated EMS intervention with a beneficial effect until tEMS + 30 min, but not thereafter; hospital intervention was associated with a strongly beneficial effect that increased with time. Rural location was associated with a higher baseline hazard; a 50% reduction in rural prehospital time would theoretically reduce 4-h mortality by about 7%. Conclusion Rural/urban disparity in crash mortality is mostly independent of time delays and EMS effects. However, survival models with TVC support clinical intuition of a "golden hour" in EMS care, and the importance of timely transport to a hospital.

Original languageEnglish (US)
Pages (from-to)141-147
Number of pages7
JournalAccident Analysis and Prevention
Volume60
DOIs
StatePublished - Sep 30 2013

Fingerprint

Emergency Medical Services
traffic
Survival
Crashworthiness
medical services
Time delay
Sampling
mortality
reporting system
Mortality
Hazards
Information Systems
time
Wounds and Injuries
Intuition
intuition
Proportional Hazards Models
Uncertainty
rural area
uncertainty

Keywords

  • Emergency medicine
  • Interval censoring
  • Mortality
  • Motor vehicle
  • Survival
  • Time-varying covariates

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Safety, Risk, Reliability and Quality
  • Human Factors and Ergonomics
  • Law
  • Medicine(all)

Cite this

Estimating the effect of emergency care on early survival after traffic crashes. / Clark, David E.; Winchell, Robert J.; Betensky, Rebecca.

In: Accident Analysis and Prevention, Vol. 60, 30.09.2013, p. 141-147.

Research output: Contribution to journalArticle

@article{2eb15b8302f542aa90545e6a328b1cb5,
title = "Estimating the effect of emergency care on early survival after traffic crashes",
abstract = "Introduction Traffic crash mortality is higher in rural areas, but it is unclear whether this is due to greater injury severity, time delays, or Emergency Medical Services (EMS) deficiencies. Methods Data from 2002-2003 were combined from the Fatality Analysis Reporting System (FARS) and an {"}expanded version{"} of the National Automotive Sampling System (NASS) Crashworthiness Data System (CDS). Weighted Cox and Weibull models for survival time (tSURV) were estimated, with time-varying covariates (TVC) having constant effects for specified time intervals following EMS arrival time (tEMS) and hospital arrival time (tHOS). The Weibull model was repeated with tSURV interval-censored to reflect uncertainty about the exact time of death, using an imputation method to accommodate interval censoring along with TVC. Results FARS contained records for 92,718 persons with fatal or incapacitating injuries, and NASS/CDS contained 5517 (weighted population of 642,716) with incapacitating injuries. All models associated mortality with increasing age, male sex, belt nonuse, higher speeds, and vehicle rollover. The interval-censored model associated EMS intervention with a beneficial effect until tEMS + 30 min, but not thereafter; hospital intervention was associated with a strongly beneficial effect that increased with time. Rural location was associated with a higher baseline hazard; a 50{\%} reduction in rural prehospital time would theoretically reduce 4-h mortality by about 7{\%}. Conclusion Rural/urban disparity in crash mortality is mostly independent of time delays and EMS effects. However, survival models with TVC support clinical intuition of a {"}golden hour{"} in EMS care, and the importance of timely transport to a hospital.",
keywords = "Emergency medicine, Interval censoring, Mortality, Motor vehicle, Survival, Time-varying covariates",
author = "Clark, {David E.} and Winchell, {Robert J.} and Rebecca Betensky",
year = "2013",
month = "9",
day = "30",
doi = "10.1016/j.aap.2013.08.019",
language = "English (US)",
volume = "60",
pages = "141--147",
journal = "Accident Analysis and Prevention",
issn = "0001-4575",
publisher = "Elsevier Limited",

}

TY - JOUR

T1 - Estimating the effect of emergency care on early survival after traffic crashes

AU - Clark, David E.

AU - Winchell, Robert J.

AU - Betensky, Rebecca

PY - 2013/9/30

Y1 - 2013/9/30

N2 - Introduction Traffic crash mortality is higher in rural areas, but it is unclear whether this is due to greater injury severity, time delays, or Emergency Medical Services (EMS) deficiencies. Methods Data from 2002-2003 were combined from the Fatality Analysis Reporting System (FARS) and an "expanded version" of the National Automotive Sampling System (NASS) Crashworthiness Data System (CDS). Weighted Cox and Weibull models for survival time (tSURV) were estimated, with time-varying covariates (TVC) having constant effects for specified time intervals following EMS arrival time (tEMS) and hospital arrival time (tHOS). The Weibull model was repeated with tSURV interval-censored to reflect uncertainty about the exact time of death, using an imputation method to accommodate interval censoring along with TVC. Results FARS contained records for 92,718 persons with fatal or incapacitating injuries, and NASS/CDS contained 5517 (weighted population of 642,716) with incapacitating injuries. All models associated mortality with increasing age, male sex, belt nonuse, higher speeds, and vehicle rollover. The interval-censored model associated EMS intervention with a beneficial effect until tEMS + 30 min, but not thereafter; hospital intervention was associated with a strongly beneficial effect that increased with time. Rural location was associated with a higher baseline hazard; a 50% reduction in rural prehospital time would theoretically reduce 4-h mortality by about 7%. Conclusion Rural/urban disparity in crash mortality is mostly independent of time delays and EMS effects. However, survival models with TVC support clinical intuition of a "golden hour" in EMS care, and the importance of timely transport to a hospital.

AB - Introduction Traffic crash mortality is higher in rural areas, but it is unclear whether this is due to greater injury severity, time delays, or Emergency Medical Services (EMS) deficiencies. Methods Data from 2002-2003 were combined from the Fatality Analysis Reporting System (FARS) and an "expanded version" of the National Automotive Sampling System (NASS) Crashworthiness Data System (CDS). Weighted Cox and Weibull models for survival time (tSURV) were estimated, with time-varying covariates (TVC) having constant effects for specified time intervals following EMS arrival time (tEMS) and hospital arrival time (tHOS). The Weibull model was repeated with tSURV interval-censored to reflect uncertainty about the exact time of death, using an imputation method to accommodate interval censoring along with TVC. Results FARS contained records for 92,718 persons with fatal or incapacitating injuries, and NASS/CDS contained 5517 (weighted population of 642,716) with incapacitating injuries. All models associated mortality with increasing age, male sex, belt nonuse, higher speeds, and vehicle rollover. The interval-censored model associated EMS intervention with a beneficial effect until tEMS + 30 min, but not thereafter; hospital intervention was associated with a strongly beneficial effect that increased with time. Rural location was associated with a higher baseline hazard; a 50% reduction in rural prehospital time would theoretically reduce 4-h mortality by about 7%. Conclusion Rural/urban disparity in crash mortality is mostly independent of time delays and EMS effects. However, survival models with TVC support clinical intuition of a "golden hour" in EMS care, and the importance of timely transport to a hospital.

KW - Emergency medicine

KW - Interval censoring

KW - Mortality

KW - Motor vehicle

KW - Survival

KW - Time-varying covariates

UR - http://www.scopus.com/inward/record.url?scp=84884566581&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84884566581&partnerID=8YFLogxK

U2 - 10.1016/j.aap.2013.08.019

DO - 10.1016/j.aap.2013.08.019

M3 - Article

C2 - 24056285

AN - SCOPUS:84884566581

VL - 60

SP - 141

EP - 147

JO - Accident Analysis and Prevention

JF - Accident Analysis and Prevention

SN - 0001-4575

ER -