Changes in Emergency Department Care Intensity from 2007–16: Analysis of the National Hospital Ambulatory Medical Care Survey

INTRODUCTION: Emergency departments (ED) in the United States (US) have increasingly taken the central role for the expedited diagnosis and treatment of acute episodic illnesses and exacerbations of chronic diseases, allowing outpatient management to be possible for many conditions that traditionally required hospitalization and inpatient care. The goal of this analysis was to examine the changes in ED care intensity in this context through the changes in ED patient population and ED care provided. METHODS: We analyzed the National Hospital Ambulatory Medical Care Survey (NHAMCS) from 2007–2016. Incorporating survey design and weight, we calculated the changes in ED patient characteristics and ED care provided between 2007 and 2016. We also calculated changes in the proportion of visits with low-severity illnesses that may be safely managed at alternative settings. Lastly, we compared ED care received and final ED dispositions by calculating adjusted relative risk (aRR) comparing ED visits in 2007 to 2016, using survey weighted multivariable logistic regression. RESULTS: NHAMCS included 35,490 visits in 2007 and 19,467 visits in 2016, representing 117 million and 146 million ED visits, respectively. Between 2007 and 2016, there was an increase in the proportion of ED patients aged 45–64 (21.0% to 23.6%) and 65–74 (5.9% to 7.5%), while visits with low-severity illnesses decreased from 37.3% to 30.4%. There was a substantial increase in the proportion of Medicaid patients (22.2% to 34.0%) with corresponding decline in the privately insured (36.2% to 28.3%) and the uninsured (15.4% to 8.6%) patients. After adjusting for patient and visit characteristics, there was an increase in the utilization of advanced imaging (aRR 1.29; 95% confidence interval [CI], 1.17–1.41), blood tests (aRR 1.16; 95% CI, 1.10–1.22), urinalysis (aRR 1.22; 95% CI, 1.13–1.31), and visits where the patient received four or more medications (aRR 2.17; 95% CI, 1.88–2.46). Lastly, adjusted hospitalization rates declined (aRR 0.74; 95% CI, 0.64–0.84) while adjusted discharge rates increased (aRR 1.06; 95%CI 1.03–1.08). CONCLUSION: From 2007 to 2016, ED care intensity appears to have increased modestly, including aging of patient population, increased illness severity, and increased resources utilization. The role of increased care intensity in the decline of ED hospitalization rate requires further study.