Infection risk highest when hospital occupancy rates between 25%-75%

Higher occupancy rates in hospitals don’t necessarily mean more infections. Rather, a facility can have the highest risk for Clostridium difficile infections when capacity was in a Goldilocks zone—not too full, not too empty—between 25 and 75 percent, according to new research from the University of Michigan and RAND Corporation.

A team—led by Mahshid Abir, MD, an assistant professor at UM Medical School—published its findings June 27 in the Journal of Hospital Medicine.

“Hospital occupancy is related to CDI,” Abir et al. wrote. “However, contrary to expectation, we found that higher admission and average occupancy over hospitalization were not related to more hospital-acquired CDI. CDI rates were highest for intermediate levels of average occupancy with lower CDI rates at high and low occupancy. CDI had an inverse relationship with admission occupancy.”

The researchers analyzed data from 550,000 patient discharges between 2008 and 2012 in California hospitals for older Medicare recipients with a discharge diagnosis of acute myocardial infarction, heart failure or pneumonia.

Intermediate occupancy groups—25 to 50 percent and 51 to 75 percent—were three times more likely of CDI compared to low and high occupancy groups. For admission occupancy, those above 50 percent had a 15 percent lower risk of CDI, though the adjusted results were similar.

“These findings suggest that an exploration of the processes associated with hospitals accommodating higher occupancy might elucidate measures to reduce CDI,” Abir and colleagues wrote. “How do staffing, implementation of policies, and routine procedures vary when hospitals are busy or quiet? What aspects of care delivery that function well during high and low occupancy periods breakdown during intermediate occupancy?

“Hospital policies, practices, and procedures during different phases of occupancy might inform best practices. These data suggest that hospital occupancy level should be a routinely collected data element by infection control officers and that this should be linked with protocols triggered or modified with high or low occupancy that might affect [hospital-acquired conditions].”