Increased Risk of Adverse Events Linked to Long Emergency Waiting Times

Long emergency department waiting times are associated with an increased risk of hospital admission or death within 7 days among non-admitted patients, according to a population-based cohort study from Ontario, Canada.

Long waiting times are associated with delays in care and several countries have set targets for the time patients wait. Most (85%) of emergency department patients go home after their visit, but whether waiting times adversely affect their outcomes is unknown.

So researchers in Canada set out to determine whether patients who present to emergency departments during shifts with long waiting times are at risk for adverse events (hospitalization or death within 7 days).

Using data from high volume emergency departments in Ontario, Canada from 2003 to 2007, they identified 13,934,542 “seen and discharged” patients and 617,011 “left without being seen” patients.

The risk of short term adverse events increased with average emergency department length of stay. Although the overall risk is low, risk of hospital admission increased by up to 95%, while risk of death increased by up to 79% among the sickest patients.

Risk of death increased incrementally with each additional hour of average shift waiting time and the authors calculate that reducing emergency department length of stay by one hour, on average, could have potentially cut the number of deaths in this study in higher risk patients by 558 (6.5%) and in lower risk patients by 261 (12.7%).

Contrary to popular belief, patients who left without being seen were not at higher risk of short term adverse events compared with patients who were seen and discharged, nor were patients who attended emergency departments with high “left without being seen” rates.

This is reassuring as there has been much uncertainty surrounding outcomes of “left without being seen” patients. However, these results suggest that presenting to emergency departments during shifts with long average waiting times may have serious patient safety implications.

“We need to extend the evaluation of emergency care to either the resolution of the problem or transfer of care to a provider better suited to tackle the patient’s needs,” Melissa McCarthy, associate professor, George Washington University, stated in an accompanying editorial.

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