Comparing institutional trauma survival to a standard: current limitations and suggested alternatives.

Many studies have evaluated trauma care in hospitals and systems using a "Preventable Death Rate" (PDR), consisting of the number of deaths judged preventable by some person or committee on the basis of autopsy or chart review divided by the total number of deaths during the same time period.1-3 This quantity may have some value if the denominator is understood to be a proxy for the total number of patients at risk for preventable death. However, interpreting a difference between two measurements of the PDR, even in the same hospital, may be difficult. For example, an increase in the number of unsalvageable patients will decrease the PDR without any change in the quality of care.4 In addition, the subjective determination of preventability is notably unreproducible from one expert committee to another;5,6 this makes the PDR unsuitable for comparison of different institutions.