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Share and share alike: Transfer pts, infections?
Patient sharing 'grossly underestimated'
Findings from the first in-depth study of patient sharing show that hospitals share large numbers of patients with other acute care facilities without knowing it. The findings do not bode well for containing emerging organisms like carbapenem-resistant Klebsiella pneumoniae because they suggest that once a pathogen enters a region, it may soon be shared among many area hospitals. Reported recently in San Diego at the annual meeting of the Society for Healthcare Epidemiology of America (SHEA), the study found that only one in nine shared patients is directly transferred from one hospital to another. Most patients were discharged before being readmitted to another hospital. This high underestimation of patient sharing has important implications for handling the potential spread of infectious disease among acute care facilities, since patient sharing could be an avenue of transmission if a major disease outbreak were to occur, the lead researcher noted.
"We were surprised to find extensive interlinking of all the hospitals included in the study," says Susan S. Huang, MD, MPH, assistant professor and hospital epidemiologist, University of California Irvine School of Medicine. "The level of patient sharing among hospitals is grossly underestimated because patients often don't transfer directly between hospitals."
The study included nearly 240,000 patient admissions.1 Researchers assessed direct and indirect transfers among all 31 acute care hospitals in Orange County, CA, a large metropolitan county of 3 million people, using a retrospective evaluation of 2005 California Hospital Discharge Data. Huang and colleagues examined the likelihood that adult patients admitted to each hospital in 2005 would subsequently be transferred or admitted to another hospital in the county in the 365 days following their discharge. The research did not include skilled nursing homes, psychiatric hospitals, or rehabilitation facilities, which, according to Huang, could mean that the amount of patient sharing among all health care facilities is even higher than their study found.
Only 16% by direct patient transfer
In 2005, 239,456 patients were admitted to OC hospitals with a median length of stay of three days. Patients were shared widely, with hospitals sharing at least one patient with a median of 28 other hospitals. Only 16% of interfacility patient sharing occurred by direct patient transfer. Among those discharged, 22% were readmitted to a median of two hospitals in the subsequent year. Median time to readmission was 23 days. When using a threshold of 10 shared patients, hospitals "exposed" 30% of other county hospitals within five months and 50% of county hospitals within 10 months.
"If you consider, for example, 10 patients as an exposure — so, I give 10 patients to you — we found that within five months, every hospital in the county, on average, exposed 30% of other county hospitals to 10 of their patients," Huang said at a SHEA press conference. "Overall, this has implications, for example, for outbreak control or control of prevalent organisms like multidrug-resistant organisms such as MRSA. If we can understand a little bit more about where high-prevalent sectors are, then understanding these traffic patterns can really favorably affect public health containment."
Huang attributed the intricate and broad connections among hospitals to three primary factors: patient choice, insurer agreements among hospitals, and immediacy of needing care.
"There was a time when patients would stay for long times in the hospital and could transfer largely directly between hospitals," she said. "But now, health care delivery is increasingly complex, and patients are sent home with home health or to a rehabilitation center or a nursing home before their next admission. That means hospitals may not know exactly who they're sharing patients with. We may not know the true value of this work until a specific pathogen is tested within this context."