Surveillance bias and deep vein thrombosis in the national trauma data bank: the more we look, the more we find.

Background: Deep vein thrombosis (DVT) has been identified as a marker of quality of care by various governmental and consumer groups. However, the lack of standardized DVT screening systems across trauma centers may introduce surveillance bias in the rates of DVT reported. We hypothesize that trauma centers with higher rates of duplex ultrasound detect more DVTs and subsequently report higher DVT rates to the National Trauma Data Bank.

Hazards of benchmarking complications with the National Trauma Data Bank: numerators in search of denominators.

Background: Complication rates after trauma may serve as important indicators of quality of care. Meaningful performance benchmarks for complication rates require reference standards from valid and reliable data. Selection of appropriate numerators and denominators is a major consideration for data validity in performance improvement and benchmarking.