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The distribution of survival times after injury
Filetype[PDF - 439.21 KB]


Details:
  • Pubmed ID:
    22402976
  • Pubmed Central ID:
    PMC3779685
  • Funding:
    R01 CA075971/CA/NCI NIH HHS/United States
    R01CE001594/CE/NCIPC CDC HHS/United States
  • Document Type:
  • Collection(s):
  • Description:
    Introduction

    The distribution of survival times after injury has been described as “trimodal”, but several studies have not confirmed this. The purpose of this study was to clarify the distribution of survival times after injury.

    Methods

    We defined survival time (ts) as the interval between injury time and declared death time. We constructed histograms for ts <=150 minutes from the 2004-2007 Fatality Analysis Reporting System (FARS, for traffic crashes) and National Violent Death Reporting System (NVDRS, for homicides). We estimated statistical models in which death times known only within intervals were treated as interval-censored. For confirmation, we also obtained EMS response times (tr), prehospital times (tp), and hospital times (th) for decedents in the 2008 National Trauma Data Bank (NTDB) with ts=tp+th<=150. We approximated times until circulatory arrest (tx) as tr for patients pulseless at the injury scene, tp for other patients pulseless at hospital admission, and ts for the rest; for any declared ts, we calculated mean tx / ts. We used this ratio to estimate tx for hospital deaths in FARS or NVDRS, and provide independent support for using interval-censored methods.

    Results

    FARS and NVDRS deaths were most frequent in the first few minutes. Both showed a second peak at 35-40 minutes after injury, corresponding to peaks in hospital deaths. Third peaks were not present. Estimated tx in FARS and NVDRS did not show second peaks, and were similar to estimates treating some death times as interval-censored.

    Conclusions

    Increases in frequency of survival times at 35-40 minutes are primarily artifacts created because declaration of death in hospitals is delayed until completing resuscitative attempts. By avoiding these artifacts, interval censoring methods are useful for analysis of injury survival times.