Study finds surprising driver of ambulance diversion

A new study looks at the role inpatient volume plays in driving ambulance diversion. (katifcam/iStock/Getty Images Plus/Getty Images)

Hospital inpatient volume may have a bigger impact on ambulance diversion than emergency department volume, according to a new study. 

Researchers examined more than 5.8 million inpatient stays and 18.7 million ED visits across 208 California hospitals between 2005 and 2012. On average, the likelihood that a hospital would go on diversion increased by 5% if inpatient volume increased by 10%, while hospitals were less than 1% more likely to go on diversion if ED volume increased by 10%. 

A 10% increase in inpatient volume also increased the length of time hospitals were on diversion by sevenfold, on average, according to the study. 


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Renee Hsia, M.D., professor of emergency medicine at the University of California, San Francisco, told FierceHealthcare that the role inpatient volume plays in increasing the duration of ambulance diversion is crucial to examine, as providers focus on reducing ED use.

"Most people think of crowded EDs as full of patients—and patients who are coming for minor treatments are often blamed as the source of overcrowding and therefore diversion," said Hsia, the study's lead author.

"But now we have some evidence to show that EDs aren't on diversion because of a bunch of patients with minor ailments crowding our space—it's more related to crowding upstairs in the rest of the hospital." 

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When the inpatient wards are full or at high capacity, it leads to significant backups in the emergency room, Hsia said. And that can stretch out diversion times. 

Hospitals can mitigate the problem by better managing and monitoring inpatient capacity. One solution, Hsia said, is to make better use of licensed of beds, which are not consistently staffed and leads to hospitals having fewer beds available for patients. 

Taking steps to address these issues is especially important in communities with smaller hospitals that may be forced to go on diversion often, which poses a significant risk to people with time-sensitive conditions. 

RELATED: Use predictive data analysis to reduce ER overcrowding, study suggests 

The researchers also looked at how diversion can impact neighboring hospitals. High-occupancy hospitals were more affected when nearby hospitals went on diversion, according to the study, and experienced between 6% and 13% more diversion hours themselves when a neighboring facility went on diversion. 

Hsia said she hopes future study digs more into how diversion can impact patient outcomes and care. Once researchers have painted a better picture of those effects, they can develop more effective strategies to improve inpatient capacity. 

"Ultimately, the effect on patients is what we care about most," she said.