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Quantifying Interhospital Patient Sharing as a Mechanism for Infectious Disease Spread

  • Susan S. Huang (a1), Taliser R. Avery (a2), Yeohan Song (a3), Kristen R. Elkins (a1), Christopher C. Nguyen (a1), Sandra K. Nutter (a4), Alaka A. Nafday, Curtis J. Condon (a4), Michael T. Chang (a1), David Chrest (a5), John Boos (a5), Georgiy Bobashev (a5), William Wheaton (a5), Steven A. Frank (a6), Richard Piatt (a2), Marc Lipsitch (a7), Robin M. Bush (a6), Stephen Eubank (a8), Donald S. Burke (a9) and Bruce Y. Lee (a10)...



Assessments of infectious disease spread in hospitals seldom account for interfacility patient sharing. This is particularly important for pathogens with prolonged incubation periods or carrier states.


We quantified patient sharing among all 32 hospitals in Orange County (OC), California, using hospital discharge data. Same-day transfers between hospitals were considered “direct” transfers, and events in which patients were shared between hospitals after an intervening stay at home or elsewhere were considered “indirect” patient-sharing events. We assessed the frequency of readmissions to another OC hospital within various time points from discharge and examined interhospital sharing of patients with Clostridium difficile infection.


In 2005, OC hospitals had 319,918 admissions. Twenty-nine percent of patients were admitted at least twice, with a median interval between discharge and readmission of 53 days. Of the patients with 2 or more admissions, 75% were admitted to more than 1 hospital. Ninety-four percent of interhospital patient sharing occurred indirectly. When we used 10 shared patients as a measure of potential interhospital exposure, 6 (19%) of 32 hospitals “exposed” more than 50% of all OC hospitals within 6 months, and 17 (53%) exposed more than 50% within 12 months. Hospitals shared 1 or more patient with a median of 28 other hospitals. When we evaluated patients with C. difficile infection, 25% were readmitted within 12 weeks; 41% were readmitted to different hospitals, and less than 30% of these readmissions were direct transfers.


In a large metropolitan county, interhospital patient sharing was a potential avenue for transmission of infectious agents. Indirect sharing with an intervening stay at home or elsewhere composed the bulk of potential exposures and occurred unbeknownst to hospitals.


Corresponding author

University of California Irvine Medical Center, Division of Infectious Diseases, 101 The City Drive South, City Tower, Suite 400, Zot Code 4081, Orange, CA 928683217 (


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1.Ostrowsky, BE, Trick, WE, Sohn, AH, et al.Control of vancomycin-resistant Enterococcus in health care facilities in a region. N Engl J Med 2001;344:14271433.
2.Valentine, SC, Contreras, D, Tan, S, Real, LJ, Chu, S, Xu, HH. Phenotypic and molecular characterization of Acinetobacter baumannii clinical isolates from nosocomial outbreaks in Los Angeles County, California. J Clin Microbiol 2008;46(8):24992507.
3.Arya, N, Howard, J, Isaacs, S, et al.Time for an ecosystem approach to public health? Lessons from two infectious disease outbreaks in Canada. Glob Public Health 2009;4(1):3149.
4.McDonald, LC, Simor, AE, Su, IJ, et al.SARS in healthcare facilities, Toronto and Taiwan. Emerg Infect Dis 2004;10(5):777781.
5.Bootsma, MC, Diekmann, O, Bonten, MJ. Controlling methicillin-resistant Staphylococcus aureus: quantifying the effects of interventions and rapid diagnostic testing. Proc Natl Acad Sci USA 2006;103(14):56205625.
6.Robotham, JV, Jenkins, DR, Medley, GF. Healthcare-associated infection epidemic behaviour and control in a network of hospitals. In: Program and asbtracts of the 18th Annual Scientific Meeting of the Society of Healthcare Epidemiology of America. Arlington, VA: Society of Healthcare Epidemiology of America, 2008.
7.Cohen, SH, Gerding, DN, Johnson, S, et al.Clinical practice guidelines for Clostridium difficile infection in adults: 2010 update by the Society for Healthcare Epidemiology of America (SHEA) and the Infectious Diseases Society of America (IDSA). Infect Control Hosp Epidemiol 2010;31 (5):431455.
8.Baker, SE, Brecher, SM, Robillard, E, Strymish, J, Lawler, E, Gupta, K. Extranasal methicillin-resistant Staphylococcus aureus colonization at admission to an acute care Veterans Affairs hospital. Infect Control Hosp Epidemiol 2010;31(1):4246.
9.Jeyaratnam, D, Whitty, CJ, Phillips, K, et al.Impact of rapid screening tests on acquisition of methicillin resistant Staphylococcus aureus: cluster randomised crossover trial. BMJ 2008;336(7650):927930.
10.Haley, CC, Mittal, D, Laviolette, A, Jannapureddy, S, Parvez, N, Haley, RW. Methicillin-resistant Staphylococcus aureus infection or colonization present at hospital admission: multivariable risk factor screening to increase efficiency of surveillance culturing. J Clin Microbiol 2007;45(9):30313038.
11.Jarvis, WR, Schlosser, J, Chinn, RY, Tweeten, S, Jackson, M. National prevalence of methicillin-resistant Staphylococcus aureus in inpatients at US health care facilities, 2006. Am J Infect Control 2007;35(10):631637.
12.Jarvis, WR, Schlosser, J, Jarvis, AA, Chinn, RY. National point prevalence of Clostridium difficile in US health care facility inpatients, 2008. Am J Infect Control 2009;37(4):263270.
13.Dubberke, ER, Wertheimer, Al. Review of current literature on the economic burden of Clostridium difficile infection. Infect Control Hosp Epidemiol 2009;30(1):5766.
14.Muto, CA, Pokrywka, M, Shutt, K, et al.A large outbreak of Clostridium difficile-associated disease with an unexpected proportion of deaths and colectomies at a teaching hospital following increased fluoroquinolone use. Infect Control Hosp Epidemiol 2005;26(3):273280.
15.Weiss, K, Boisvert, A, Chagnon, M, et al.Multipronged intervention strategy to control an outbreak of Clostridium difficile infection (CDI) and its impact on the rates of CDI from 2002 to 2007. Infect Control Hosp Epidemiol 2009;30(2):156162.


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