title: Lead-Time Bias and Interhospital Transfer after Injury: Trauma Center Admission Vital Signs Underpredict Mortality in Transferred Trauma Patients.
abstract: BACKGROUND
  Admission physiology predicts mortality after injury, but may be improved by resuscitation before transfer. This phenomenon, which has been termed lead-time bias, may lead to underprediction of mortality in transferred patients and inaccurate benchmarking in centers receiving large numbers of transfer patients. We sought to determine the impact of using vital signs on arrival at the referring center vs on arrival at the trauma center in mortality prediction models for transferred trauma patients.
  
  
  METHODS
  We performed a retrospective cohort study using a state-wide trauma registry including all patients age 16 years or older, with Abbreviated Injury Scale scores ≥ 3, admitted to level I and II trauma centers in Pennsylvania, from 2011 to 2014. The primary outcomes measure was the risk-adjusted association between mortality and interhospital transfer (IHT) when adjusting for physiology (as measured by Revised Trauma Score [RTS]) using the referring hospital arrival vital signs (model 1) compared with trauma center arrival vital signs (model 2).
  
  
  RESULTS
  After adjusting for patient and injury factors, IHT was associated with reduced mortality (odds ratio [OR] 0.85; 95% CI 0.77 to 0.93) using the RTS from trauma center admission, but with increased mortality (OR 1.15; 95% CI 1.05 to 1.27) using RTS from the referring hospital. The greater the number of transfer patients seen by a center, the greater the difference in center-level mortality predicted by the 2 models (β -0.044; 95% CI -0.044 to -0.0043; p ≤ 0.001).
  
  
  CONCLUSIONS
  Trauma center vital signs underestimate mortality in transfer patients and may lead to incorrect estimates of expected mortality. Where possible, benchmarking efforts should use referring hospital vital signs to risk-adjust IHT patients.
authors.affiliation: Division of Traumatology, Surgical Critical Care and Emergency Surgery, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA; Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA; The Penn Injury Science Center at the University of Pennsylvania, Philadelphia, PA. Electronic address: Daniel.holena@uphs.upenn.edu.
authors.forename: Daniel N
authors.initials: DN
authors.lastname: Holena
authors.affiliation: Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA; The Penn Injury Science Center at the University of Pennsylvania, Philadelphia, PA.
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Wiebe
authors.affiliation: Department of Emergency Medicine, Jefferson University School of Medicine, Philadelphia, PA.
authors.forename: Brendan G
authors.initials: BG
authors.lastname: Carr
authors.affiliation: Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA.
authors.forename: Jesse Y
authors.initials: JY
authors.lastname: Hsu
authors.affiliation: Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA.
authors.forename: Jason L
authors.initials: JL
authors.lastname: Sperry
authors.affiliation: Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Peitzman
authors.affiliation: Division of Traumatology, Surgical Critical Care and Emergency Surgery, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA; The Penn Injury Science Center at the University of Pennsylvania, Philadelphia, PA.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Reilly
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D017052:Hospital Mortality; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D010360:Patient Transfer; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D014193:Trauma Centers; D015599:Trauma Severity Indices; D055986:Vital Signs; D014947:Wounds and Injuries / Q000175:diagnosis / Q000401:mortality* / Q000503:physiopathology