While working at various academic medical centers as a researcher, Lindsey Woodworth, PhD, noticed that many patients in the ED waited hours to be seen.

“Along with that, I would hear stories of patients crashing and occasionally dying in the waiting room,” says Woodworth, an assistant professor in economics at the University of South Carolina.

Woodworth suspected there was a strong relationship between how crowded an ED is at a patient’s time of arrival and that patient’s likelihood of surviving. She decided to see whether data supported this by looking at existing South Carolina EDs in locations where a new ED opened recently. “There is an instantaneous reduction in crowding in existing EDs when a new ED opens nearby,” she explains.

Woodworth used hospital records to determine how many patients visited the EDs each day, and analyzed the patient volume and death rates. She found that if ED patient volume is alleviated by just 10%, it significantly lowers the average patient’s chance of mortality.1 Woodworth observed decreased mortality rates both during the ED visit and after discharge.

“What was surprising was the suggestive evidence that patients are more likely to die after their visit when they are exposed to more crowding,” Woodworth says.

Patients are more likely to leave without being seen when care is delayed because of ED crowding.2,3 “It could be that some of the increased mortality is due to patients walking out of the ED, going home, and then dying,” Woodworth offers.

Considering this unexpected finding, says Woodworth, “EDs could focus on reducing their rates of patients leaving without being seen. Clearly, lowering wait times would be one way to encourage patients to stay.”

The first step is for EDs to be aware of the direct link between patient volumes and patient outcomes. “EDs can then take steps to improve patient flow when crowding is high,” Woodworth explains.


  1. Woodworth L. Swamped: Emergency department crowding and patient mortality. J Health Econ 2020;70:102279.
  2. Stang AS, McCusker J, Ciampi A, Strumpf E. Emergency department conditions associated with the number of patients who leave a pediatric emergency department before physician assessment. Pediatr Emerg Care 2013;29:1082-1090.
  3. Rowe BH, Channan P, Bullard M, et al. Characteristics of patients who leave emergency departments without being seen. Acad Emerg Med 2006;13:848-852.