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Hospital Occupancy Impacts Infection Risk in Unexpected Ways

Analysis  |  By Kenneth Michek  
   July 05, 2018

The greatest risk of patients acquiring a C. diff infection didn't come, surprisingly, when hospitals were at their fullest.

When researchers from the University of Michigan and RAND set out to explore the relationship between hospital occupancy and C. diff infection risk, they expected to find that high census would mean greater risk for infection.   

But, after analyzing data for a new study published in the Journal of Hospital Medicine, they found some surprising results. Patients were more at risk for C. diff infections when the hospital was moderately Patfull.

"The theory that infection rates will go up with occupancy, because of staff cutting corners with steps like handwashing, may seem logical but this model shows it’s not as simple as that," says the study's lead author Mahshid Abir, MD, MSc

Unexpected Results

The study used data from 558,829 patient discharges at 327 hospitals across California, between 2008 and 2012. It focused on patients who had come to the hospitals’ emergency departments for care for a heart attack, heart failure, or pneumonia.

In all, 2,045 patients developed a C. diff infection after reaching the hospital.

The authors compared C. diff infection rates to hospital occupancy information, and looked for a correlation between the two factors.

Occupancy was broken into four levels:

  • Low (0 to 25% occupied)
  • Two classes of moderate (25% to 50% occupied and 51% to 75% occupied)
  • High (76% occupied to completely full)

They found C. diff infection risk was highest when the hospital was in the moderate range of occupancy on the day the patient was admitted. And, when the researchers looked at the average occupancy over a patient’s stay, the risk of C. diff infection was more than three times higher when a hospital was moderately full compared to when they were at low or high occupancy.

"Our initial results indicate a complex relationship between hospital occupancy and outcomes, and merit further evaluation," says Abir, who leads the UM Acute Care Research Unit and is a member of the UM Institute for Healthcare Policy and Innovation.

More Data Collection Needed

Based on their initial findings, Abir and her co-authors call for collection of hospital occupancy data by infection control officers so that more precise measurements of occupancy can be used when examining HAIs and other preventable threats to patient health and safety.

They also recommend analysis of hospital protocols that might be triggered or modified when a hospital is in high or low occupancy.  

"The impacts of emergency department crowding on patient outcomes have been studied extensively, but the effects of occupancy levels on inpatients has been neglected – despite the fact that a crowded ED is often a function of high inpatient occupancy," Abir says. "Some hospitals may be implementing operational factors during high occupancy that improve HAIs. We need to study what those are."

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