Increasing blood culture use at US hospital emergency department visits, 2001 to 2004

Study objective: We describe emergency department (ED) visits in which patients had blood cultured and examine changes in blood culture use. Methods: Data from the 2001 to 2004 National Hospital Ambulatory Medical Care Survey, an annual sample survey of visits to US hospital EDs, were analyzed. About 400 EDs reported data for approximately 37,000 visits each year. Trends in blood culture use were examined among persons 3 months of age and older. Visits by admitted/transferred patients were compared to those released. Results: About 3.1 million blood cultures were ordered annually in US EDs; blood cultures were ordered at 2.8% of all visits. From 2001 through 2004, the proportion of visits where a blood culture was ordered increased by 33%, particularly in adults. The proportion of visits with a pneumonia diagnosis where a blood culture was ordered rose by 23% during the study period; these visits accounted for 22% of the increase in blood culture use among admitted patients. Almost half of blood cultures were ordered at visits in which the patient was released from the ED. For visits by released patients 3 years of age and older who had blood cultured, 43% had neither fever nor antibiotic prescriptions. Conclusion: There is an increasing national trend in the use of blood cultures at adult patient ED visits; a large proportion of these cultures were for released patients without apparent indicators for bacteremia, such as fever or antibiotic prescriptions. Factors and impact associated with this dynamically changing practice need further evaluation.