In researching our cover package on aeromedical evacuation, one of the hardest things to grapple with was how to count casualties. It turns out that even those experienced in the field can become confused on what metric is the most appropriate to use in any given circumstance.
So for help, I turned to Col. (Dr.) Mark Ervin, the medical director for the US Air Force's Critical Care Air Transport Team and Tactical Critical Care Evacuation Team programs, who took me through a fascinating -- and illuminating -- comparison of the three main ways physicians and researchers involved in trauma medicine measure how well servicemembers fare after they've been wounded: Case Fatality Rate, or CFR, Killed in Action (KIA) and Died of Wounds (DOW).
Dr. Ervin believes, and I think convincingly demonstrates, that if we want to understand the overall lethality of a given conflict the Case Fatality Rate is the most meaningful.
"Only the CFR takes into account all wounded combatants and assesses the totality of the risk of death" from the moment and location in which a servicemember is hurt through the entire span of medical care, transport and the return home, he says.
While KIA and DOW seem pretty straightforward, their principal shortcoming is that they only measure the isolated likelihood of survival at specific moments during the patient's passage through the medical care system. Mathematically, KIA is the percentage of significantly injured servicemembers who die before reaching a deployed medical facility. Died of Wounds looks at what percentage of the badly injured who arrive alive at a deployed medical facility die later on for reasons that relate to those wounds.
Compare those with CFR. This statistic counts all combatants wounded in action who ultimately die from their injuries, at any point along the care continuum from point of injury all the way to medical centers in the U.S. In a talking paper prepared to clear up confusion about these metrics for Operation Enduring Freedom, Ervin notes that "the lethality of the employed weapons, the efficacy of battlefield/en-route pre-hospital care, and the effectiveness of deployed trauma hospital treatments will all impact the calculated value of the CFR."
Using the CFR calculation, Operation Enduring Freedom has experienced an overall case fatality rate of 8.6%. During the Vietnam conflict, CFR was 16.1%, and in World War II it was 19.1%. Using airpower to put more advanced care into forward areas than ever before possible is saving many more lives than had been saved under previous care models -- and that's math that means all the world to servicemembers and their families.