Ambulance transport to the emergency department: A patient-selected signal of acuity and its effect on resource provision

Published:August 29, 2018DOI:



      To determine whether ambulance arrival to the emergency department has remained an unidentified signal of perceived medical acuity. Informed by economic signaling theory, does arrival via ambulance affect resource utilization given varying levels of patient acuity?


      The analysis examined a nationally representative sample of de-identified emergency department patient encounters from 2011 to 2015, gathered from the National Hospital Ambulatory Medical Care Survey (NHAMCS). Multivariate logistic regression analysis was employed using regional and time-fixed effects. The provision of twenty diagnostic and imaging services was analyzed. Patient encounters were also categorized into five acuity-levels.


      Drawing from the NHAMCS dataset, 98,888 emergency department records were analyzed, weighted to represent 504.5 million estimated emergency department patient encounters. Findings suggest that patients transported to the hospital via ambulance are more likely than those who arrive by other means to receive 19 of the 20 analyzed diagnostic testing and imaging services. Furthermore, when analyzed by acuity-level, the disparity of service provision is the greatest among low-acuity patients, where medical complaints are argued to be the most subjective.


      The results are consistent with the notion that emergency department medical providers readily accept ambulance transport as a valid signal of patient acuity, regardless of true acuity level. Consequently, patients transported to the hospital via ambulance may be receiving a disproportionate amount of medical resources in an increasingly cost-conscious environment.


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