Busiest EDs Have Best Outcomes

Neil Osterweil

July 21, 2014

Patients who present to extremely busy emergency departments (EDs) can count themselves lucky, suggest results of a new study showing that the highest-volume EDs have the best track record.

A review of more than 17 million discharges from 2960 US hospitals showed that patient deaths decreased as emergency department (ED) volume increased, both overall and for each of 8 different diagnoses, report Keith E. Kocher, MD, MPH, an emergency physician at the University of Michigan, Ann Arbor, Health System, and colleagues.

Patients admitted to the hospital after presentation to the highest-volume EDs had a 10% lower risk for in-hospital death compared with patients admitted after presenting to the lowest-volume EDs.

If the level of care at all of the lower-volume institutions could be brought up to that of the busiest EDs, an estimated 24,000 additional lives could be saved annually, the investigators write in an article published online July 16 in the Annals of Emergency Medicine.

"Our analysis demonstrated a positive correlation between higher-volume EDs and improved patient outcomes for early 2-day and for overall inpatient mortality. To our knowledge, this is the first comprehensive analysis describing the overall trend linking higher ED volume to better outcomes among hospitalized patients. This relationship persisted for all patients admitted through the ED, as well as for those with 8 higher-risk clinical conditions commonly observed in the ED," the authors write.

"It's too early to say that based on these results, patients and first responders should change their decision about which hospital to choose in an emergency," Dr. Kocher said in a university news release. "But the bottom line is that emergency departments and hospitals perform differently — there really are differences in care, and they matter."

The authors drew data from the Nationwide Inpatient Sample, a national database of hospital discharges, They looked at overall mortality rates and deaths for 8 diagnoses commonly seen in the ED: pneumonia, congestive heart failure, sepsis, acute myocardial infarction, stroke, respiratory failure, gastrointestinal bleeding, and acute and unspecified renal failure.

After excluding hospitals with fewer than 1000 annual admissions and fewer than 30 cases of each of the clinical diagnoses, they arrived at a final sample including 17,554,356 cases from 2960 hospitals from 2005 through 2009.

In regression analyses looking at the relationship between ED volume (in quintiles) and early in-hospital mortality (within 2 days of admission) and overall mortality, the authors found an inverse relationship between mortality and hospital volume, with the EDs in the highest quintiles having the lowest incidence of mortality.

Notably, the greatest absolute difference in adjusted mortality rates between the highest-volume and lowest-volume EDs was a −5.6% (95% confidence interval [CI], −6.5% to −4.7%) change in incidence of deaths from sepsis. The smallest but still significant difference between the busiest and least busy EDs was a −0.2% (95% CI, −0.6% to 0.1%) difference in incidence of pneumonia-related deaths in high-volume centers.

The overall difference in mortality among all admitted patients was a −0.4% (95% CI, −0.6% to −0.3%) change in incidence in the highest vs lowest quintiles by ED volume.

"Deciding how best to make operational the volume-outcome relationship to emergency care delivery will be determined by identifying the underlying mechanisms for variation in patient outcomes. For example, in surgical patients it has been found that pre- and perioperative interventions explain some of the variation in patient outcomes related to volume. Therefore, future research to understand differences or similarities between care processes and implementation of best practices at high- versus low-volume EDs will better identify how to intervene to optimize outcomes across all EDs," the authors write.

The authors have disclosed no relevant financial relationships.

Ann Emerg Med. Published online July 16, 2014. Abstract


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