Mortality Benefit of Transfer to Level I versus Level II Trauma Centers for Head-Injured Patients


  • K. John McConnell,

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    • Address correspondence to K. John McConnell, SW Sam Jackson Park Road, Mail code CR-114, Portland, OR 97239-3098. John McConnell, Craig D. Newgard, and Jerris R. Hedges are with Center for Policy and Research in Emergency Medicine, Department of Emergency Medicine, Oregon Health & Science University, Portland, OR. Richard J. Mullins is with Trauma/Critical Care Section, Department of Surgery, Oregon Health & Science University, Portland, OR. Melanie Arthur is with Department of Sociology, Portland State University, Portland, OR.

  • Craig D. Newgard,

  • Richard J. Mullins,

  • Melanie Arthur,

  • Jerris R. Hedges


Objective. To determine whether head-injured patients transferred to level I trauma centers have reduced mortality relative to transfers to level II trauma centers.

Data Source/Study Setting. Retrospective cohort study of 542 patients with head injury who initially presented to 1 of 31 rural trauma centers in Oregon and Washington, and were transferred from the emergency department to 1 of 15 level I or level II trauma centers, between 1991 and 1994.

Study Design. A bivariate probit, instrumental variables model was used to estimate the effect of transfer to level I versus level II trauma centers on 30-day postdischarge mortality. Independent variables included age, gender, Injury Severity Scale (ISS), other indicators of injury severity, and a dichotomous variable indicating transfer to a level I trauma center. The differential distance between the nearest level I and level II trauma centers was used as an instrument.

Principal Findings. Patients transferred to level I trauma centers differ in unmeasured ways from patients transferred to level II trauma centers, biasing estimates based on standard statistical methods. Transfer to a level I trauma center reduced absolute mortality risk by 10.1% (95% confidence interval 0.3%, 22.2%) compared with transfer to level II trauma centers.

Conclusions. Patients with severe head injuries transferred from rural trauma centers to level I centers are likely to have improved survival relative to transfer to level II centers.