Interpreting process indicators in trauma care: construct validity versus confounding by indication.

OBJECTIVE Quality indicators (QIs) are routinely used in health systems, often on the assumption that they provide a valid reflection of the outcome of care. This study investigated the construct validity of 14 trauma QIs through their ability to identify patients at risk of poor outcomes, including increased mortality, longer lengths of stay and greater use of the intensive care unit (ICU). METHODS Data were analysed from the Victorian State Trauma Registry from January 2001 to March 2006. Patients included blunt trauma, injury severity score >15 and aged >16 years. Univariate analyses and logistic regression modeling were used to adjust for significant covariates. RESULTS The study included 5104 cases. Three QIs were associated with increased mortality (abdominal surgery >24 h after arrival, blunt compound tibial fracture treatment >8 h after arrival and non-fixation of femoral diaphyseal fracture) and three with increased lengths of stay (cranial or abdominal surgery >24 h after arrival and patients developing deep vein thromboses, pulmonary emboli or decubitus ulcers, the latter also associated with increased ICU use). All remaining QIs exhibited reduced risks of poor outcomes or no significant associations. CONCLUSION The investigated QIs generally demonstrated poor construct validity and limited usefulness in predicting outcomes. Although QIs associated with poor patient outcomes may represent an avenue for further refinement, additional investigation of QIs in comparative trauma systems could provide insight into the utility of these measures at the system level.