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also stated that “. . . there is little doubt that this trend is in Although there is no doubt that hospital care saves lives, data
large part caused by the more systematic and rapid application and metrics to measure the degree of impact of each life-saving
of evidence-based trauma care to injured service personnel.” hospital capability have been difficult to capture, as many hos-
Although the timely application of trauma care most certainly pital capabilities are interdependent and intertwined. While
played a major part in the reduction of the CFR, how large it is reasonable to hypothesize that hospital improvements
a part trauma care actually played, and the degree to which occurred, it has been difficult to measure the impact of each
each specific trauma care intervention contributed, is difficult specific hospital intervention on reducing the battle-injured
to determine accurately given just the CFR. Also needing con- CFR or %DOW because advancements in data and metrics to
sideration for their part in reducing the CFR (i.e., preventive evaluate the trauma care system with this level of precision still
fraction) are non-medical interventions (e.g., logistics; tactics, need to be developed. Further, adequate assessment requires
techniques, procedures [TTPs]; personal protective equipment that a meaningful number of casualties with life-threatening
[PPE]). 7 injuries amenable to specific hospital interventions survive
long enough to benefit from such care. Evidence of improve-
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When a subsequent comprehensive review of available factors ment in hospital care and outcomes certainly exists. However,
was published in 2019, three military medicine efforts were data and metrics are currently unable to tease out which spe-
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attributed to reducing the battle-injured CFR: 1) increased use cific hospital interventions were responsible for improvements
of limb tourniquets, 2) increased use of blood transfusions, and that also had a large enough impact to be reflected in aggre-
3) rapid prehospital transport to facilities with surgical capa- gate statistics such as the CFR or %DOW. This is an opportu-
bilities. Based on the available data, these three interventions nity for improvement of data capture, metrics, and research on
accounted for an estimated 44% of the observed reduction hospital combat casualty care.
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in combat fatalities from 2001 to 2017. The remaining 56%
of the observed reduction was multifactorial and attributed Integrating Mortality Review Statistics
to either other or unexplained factors. The other factors such
as differences in mechanism of injury and injury severity may To better understand the specific impact of military medicine
be proxies for non-medical factors that could not be assessed on reducing the battle-injured CFR, we recommend integrat-
because of insufficient data for changes in environment, PPE, ing the CFR with two additional statistics derived from the
munitions, or offensive and defensive TTPs. Similarly, these Military Trauma Mortality Review process 10–14 : percentage
unexplained factors may be improvements in medical care that of fatalities with potentially survivable (PS) injuries and po-
lacked the adequate precision of documentation, data capture, tentially preventable (PP) deaths (Table 1). Excluding fatali-
and metrics to meaningfully evaluate these improvements. No- ties deemed to have non-survivable injuries to formulate a PS
tably, it was the focus on robust documentation and capture case fatality rate (PS-CFR) and excluding fatalities deemed to
of tourniquet use and blood transfusions that allowed for the have non- preventable deaths to formulate a PP case fatality
historically meaningful assessments of these interventions. Al- rate (PP-CFR) allows for a clearer understanding of the op-
though the use of limb tourniquets and blood transfusions was timal distribution of investments in medical and non-medical
a lesson relearned from prior conflicts and not unique military interventions that will yield a reduction in fatalities. The sub-
medical advancements of the 21st century, such interventions tle but important distinction between PS-CFR and PP-CFR
were first implemented in the hospitals and then used aggres- resides in the difference between the definitions of injury
sively and ubiquitously during recent conflicts, resulting in im- survivability and death preventability. 12–14 Injury survivabil-
provements large enough to be reflected in the CFR. ity determinations (survivable [S], potentially survivable [PS],
non- survivable [NS]) are based on assumptions of ideal circum-
Although primarily prehospital and resuscitative interventions stances, immediate knowledge of all injuries, and immediate
were able to be measured, and not hospital or surgical inter- availability of all Level I trauma center capabilities; whereas,
ventions, the data support that reaching a surgical capability death preventability determinations (preventable [P], poten-
alive afforded survival benefit. Teasing out the individual con- tially preventable [PP], non-preventable [NP]) are based on the
tributions of the multiple simultaneous hospital-based inter- reality of actual circumstances and the tactical influences of the
ventions is difficult. Additionally, it can also be assumed that environment and enemy, which impose limitations on optimal
casualties that have life-saving prehospital interventions are re- and timely care.
liant on subsequent timely and effective surgical interventions
to affect ultimate survival. Thus, it is reasonable to hypothesize These revised combat casualty statistics highlight three main
that casualty status transitions occurred due to non-medical, hypothetical scenarios (Figure 1). By incorporating data from
prehospital, and hospital interventions; that is, fatality catego- both injury survivability and death preventability, these three
ries were shifted from KIA to DOW, KIA to alive, and DOW to scenarios can better inform the use of both medical and non-
alive. Analyses of these transitions supported the interpretation medical opportunities for improvements to reduce preventable
that thousands of Servicemembers ultimately survived who death.
would have otherwise died without non-medical, prehospital,
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and hospital interventions. In turn, this suggests that hospital Hypothetical Scenario 1
and surgical capabilities met the challenge of caring for more Military medical investment argues for an opportunity to in-
critically injured casualties who reached their facilities alive. vest specifically in medical capabilities (e.g., revised prehospi-
However, the extent to which reductions in these aggregate tal and hospital clinical practice guidelines; increased medical
statistics reflect adherence to current evidence-based trauma personnel, training, and equipment; faster transport and more
care practices or specific innovations or changes in hospital ca- efficient hand-off of casualties) to reduce preventable death.
pability (e.g., novel procedures, standardized clinical practice The rationale is that the battle-injured CFR, PS-CFR, and PP-
guidelines, medical logistics, medical training, rapid transport CFR statistics are similar. Therefore, in scenario 1 a high pro-
to higher roles of care) remains difficult to discern. portion of the fatalities sustained injuries deemed PS and did

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