1313. Defining “Nosocomial” – Differences in MDRO and C. difficile Rates Using 2-Day vs. 3-Day Definitions
Session: Oral Abstract Session: Challenges in C. difficile Infection Surveillance
Saturday, October 20, 2012: 10:45 AM
Room: SDCC 29 ABCD

Background: The CDC's 48-hour nosocomial definition is commonly implemented as a two or three-calendar day rule by hospitals. Our prior work in Orange County (OC), CA hospitals found that one-third of hospitals each used 48-hour, >2 day, >3 day case definitions.  We now assess the impact of definition choice on acquisition and infection rates.

Methods: We conducted a prospective survey of Infection Prevention Programs in OC hospitals to assess the impact of using a >2 day vs. >3 day definition for nosocomial rates of MRSA, VRE, ESBL (Klebsiella and E. coli), and MDR Acinetobacter acquisition, as well as MRSA bacteremia and C. difficile infection. Respondents provided monthly data using both definitions from January-December 2010. Total patient day denominators were retrieved from a mandatory state discharge dataset. Differences in mean rates between the two nosocomial definitions were assessed using two-tailed t-tests.

Results: Nineteen of 31 countywide hospitals participated, with a total of 1,062,242 patient days in 2010. Across pathogens, we found that use of the >3-day nosocomial definition resulted in acquisition rates that were, on average, 17% (range 9-24%) lower than use of a >2-day definition.

Table. Percent Lost to Capture by using >3d vs. >2d Day Nosocomial Definitions

Pathogen

Mean Hospital

Nosocomial Rate Using >2d Definition

(Events/10,000 total patient days)

Mean Hospital

Nosocomial Rate

Using >3d Definition

(Events/10,000 total patient days)

Paired t-test

p-value

% Countywide Events Lost by Using >3d vs. >2d Definition

Acquisition

 

 

 

 

MRSA

5.74

4.36

0.002

24%

VRE$

3.20

2.93

0.01

9%

ESBL*

2.65

2.18

0.001

17%

MDR Acinetobacter

1.12

0.99

0.03

12%

Infection

 

 

 

 

MRSA Bacteremia

0.39

0.29

0.03

24%

C. difficile Infection

6.24

5.29

<0.001

15%

*ESBL (Klebsiella and E. coli) combined; $Data from 18 hospitals

Conclusion: The common use of a >3-day definition for reporting nosocomial acquisition and infections produces significantly lower rates than a >2-day definition. This difference could substantially impact hospital rankings for public reports based upon differences in definitions alone. These data support the CDC's decision to standardize nosocomial assessment using a >2 calendar day rule in January 2013.

Adrijana Gombosev, BS1, Salah Fouad, MS2, Eric Cui, BS3, Leah Terpstra, BA4, Diane Kim, BS3, Hildy Meyers, MD MPH5, Michele Cheung, MD MPH5 and Susan S. Huang, MD, MPH, FIDSA3, (1)Department of Medicine, University of California Irvine, School of Medicine, Irvine, CA, (2)Saddleback Memorial Medical Center, Laguna Hills, CA, (3)Department of Medicine, University of California Irvine, Irvine, CA, (4)University of California Irvine, School of Medicine, Irvine, CA, (5)Epidemiology and Assessment, Orange County Health Care Agency (OCHCA), Santa Ana, CA

Disclosures:

A. Gombosev, None

S. Fouad, None

E. Cui, None

L. Terpstra, None

D. Kim, None

H. Meyers, None

M. Cheung, None

S. S. Huang, None

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