Survival after severe trauma and survival benchmarked against predicted risk improved significantly at our center during the past 12 years despite generally increasing age and worsening injuries. Advances in trauma care have kept pace with an aging population and greater severity of injury, but overall survival has not improved.

Maintaining good hospital records during military conflicts can provide medical personnel and researchers with feedback to rapidly adjust treatment strategies and improve outcomes. But to convert the resulting raw data into meaningful conclusions requires clear terminology and well thought out equations, utilizing consistent numerators and denominators. Our objective was to arrive at terminology and equations that would produce the best insight into the effectiveness of care at different stages of treatment, either pre or post medical treatment facility care. We first clarified three essential terms: 1) the case fatality rate (CFR) as percentage of fatalities among all wounded; 2) killed in action (KIA) as percentage of immediate deaths among all seriously injured (not returning to duty); and 3) died of wounds (DOW) as percentage of deaths following admission to a medical treatment facility among all seriously injured (not returning to duty). These equations were then applied consistently across data from the WWII, Vietnam and the current Global War on Terrorism. Using this clear set of definitions we used the equations to ask two basic questions:What is the overall lethality of the battlefield? How effective is combat casualty care? To answer these questions with current data, the three services have collaboratively created a joint theater trauma registry (JTTR), cataloging all the serious injuries, procedures, and outcomes for the current war. These definitions and equations, consistently applied to the JTTR, will allow meaningful comparisons and help direct future research and appropriate application of personnel. Key Words:Combat, Casualty, Statistics. A ccurate understanding of the epidemiology and outcome of battle injury is essential to improving combat casualty care, but combat trauma data are acquired under notoriously difficult circumstances and involve degrees and contexts of injury and care unfamiliar to many practitioners, civilian or military. Further, the ready availability of raw battle casualty data on the Internet invites misinterpretation by those not familiar with its pitfalls. Much of the potential for such misinterpretation boils down to familiar epidemiologic problems of consistency of numerators and denominators.The United States Department of Defense (DoD) maintains two Internet Websites providing information on battle casualties. 1,2The Defense link website has data on return to duty casualties (RTD) 1 white the site maintained by the Directorate for Information Operations and Reports (DIOR) 2 provides information from the current and past conflicts in sufficient detail for calculation of proportional mortality (that is, the fraction of an exposed groupthose injured in combat-who die, expressed as a percent), suggesting that battle mortality for injured United States forces has dropped from 30% in World War II to 24% in Vietnam to less than 10% in the current conflict.