138 Countywide Hospital Risks of Clostridium difficile Infection (CDI) and the Impact of Including Post-Discharge Events

Friday, March 19, 2010
Grand Hall (Hyatt Regency Atlanta)
Courtney Reynolds, MS , School of Social Ecology and Health Policy Research Institute, University of California Irvine School of Medicine, Irvine, CA
Taliser R. Avery, BS , Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA
Erik R. Dubberke, MD, MSPH , Department of Medicine, Washington University School of Medicine, St. Louis, MO
Susan S. Huang, MD, MPH , Division of Infectious Diseases and Health Policy Research Institute, University of California Irvine School of Medicine, Orange, CA

Background: CDI is a frequent cause of diarrhea in hospitalized patients, and can lead to colectomy and death. Mandatory reporting of hospital-associated CDI (HA-CDI) is being considered in several states, making standardized methods crucial for inter-hospital comparisons. Current capture of HA-CDI may be substantially underestimated because of failure to include post-discharge events.

Objective: To assess burden and trends in HA-CDI and community-associated CDI (CA-CDI), and to assess the changes in hospital-associated risks of CDI when post discharge events were included.

Methods: We conducted a retrospective cohort study of all 29 hospitals serving adults in Orange County, CA from 2000-2007. We used a mandatory statewide hospital discharge dataset which includes up to 25 diagnoses codes per admission, each with a linking variable identifying whether it was present on admission. We estimated HA-CDI risk and trends (chi square tests), and evaluated the effect of assigning CA-CDI cases occurring within 12 weeks post-discharge to the most recent hospitalization (t-tests). Recurrent CA-CDI cases occurring within 8 weeks of a prior episode were excluded.

Results: From 2000-2007, we found that the annual risk of HA-CDI among patients hospitalized in Orange County increased from 15 to 22 per 10,000 admissions (P<0.001), while community risks increased from 17 to 37 cases per 100,000 Orange County residents (P<0.001). We further found that a substantial component of the increase in community CDI risk was due to healthcare exposures. When post-discharge events were attributed to the most recent hospitalization within 12 weeks, HA-CDI risks increased to 29/10,000 admissions in 2000 and 52/10,000 admissions in 2007. Overall, inclusion of post-discharge events increased hospital-specific CDI risks by 150% (range 0->900%; P=0.002). In contrast, reattribution of such events caused community risks to fall by 50% to 9 per 100,000 Orange County residents in 2000 and 19/100,000 in 2007 (figure).

Conclusions: Hospital associated CDI burden was markedly affected by inclusion of CDI events occurring within 12 weeks after hospital discharge. Rising CDI burden in a large metropolitan county appeared attributed to community-associated events until post-discharge reattribution was performed. Inclusion of post-discharge CDI events in hospital-associated rates would greatly improve estimation of CDI risk among inpatient populations.


Figure: Community and hospital risks of C.difficile in Orange County, 2000-2007 with and without reattributing post-discharge events to the most recent hospitalization within 12 weeks. Hospital risk is per 10,000 hospital admissions; community risk is per 100,000 inhabitants.