498. Evaluation of Surgical Site Infections (SSIs) Excluded by the Updated SSI Surveillance Definitions
Session: Poster Abstract Session: Surgical Site Infections
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Background: The 2013 CDC/NHSN definitions for SSI included 2 major changes: the need for prolonged surveillance was standardized by procedure type rather than presence of implanted material, and the duration of prolonged surveillance was reduced from 1 year to 90 days post-operatively (DPO).  We assessed how these changes would impact SSI detection.

Methods: We analyzed prospectively collected SSI surveillance data from 35 acute care hospitals and 2 ambulatory surgical centers participating in the Duke Infection Control Outreach Network (DICON) to compare the number of SSI detected by the old and new definitions.  All surgeries performed between January 1, 2010 and December 31, 2011 were included in the analysis.

Results: Out of 235,574 surgeries, 2,420 SSIs were detected using the prior SSI definitions (rate 1.03 SSI/100 procedures) and 2,187 were detected using the new definitions (rate 0.93 SSI/100 procedures).  Of the 233 (9.6%) SSIs that were excluded by the new definitions, 71 (30%) occurred > 30 DPO in procedure types no longer designated for prolonged surveillance.  The remaining 162 (70% of excluded SSIs) occurred in procedure types designated for prolonged surveillance and were excluded because they occurred >90 DPO. Sixty-five (40%) of these occurred > 180 DPO.  The proportion of excluded SSI varied depending on procedure type (Table 1).  Notably, the new definition excluded a substantial number of SSIs occurring after knee replacement surgeries (25%) and open fracture repairs (21%). 

Conclusion: Use of the 2013 SSI surveillance definitions leads to omission of almost 10% of previously identified SSIs.  Rates of SSI using the new definitions for procedures involving implanted material, particularly knee prostheses and open fracture repairs, cannot be reasonably compared to rates derived using prior surveillance definitions. 

Table 1.  Comparison of SSI by old and new definitions for select procedure types.

Procedure type

Total surgeries

SSI old definition

SSI new definition

SSI excluded, n (%)

Knee prosthesis (KPRO)

20,767

203

152

51 (25)

Open fracture repair (FX)

14,361

149

117

32 (21)

Coronary Artery Bypass Grafting (CBGC, CBGB)

5,065

68

60

8 (12)

Breast surgery (BRST)

17,468

142

127

15 (11)

Hip prosthesis (HPRO)

12,200

181

165

16 (9)

Kristen Dicks, MD, Sarah S. Lewis, MD, Rebekah W. Moehring, MD, MPH, Luke F. Chen, MBBS, MPH, CIC, FRACP, Michael Durkin, MD, Arthur Baker, MD, Daniel J. Sexton, MD, FIDSA and Deverick Anderson, MD, MPH, Duke University Medical Center, Durham, NC

Disclosures:

K. Dicks, None

S. S. Lewis, None

R. W. Moehring, None

L. F. Chen, Merck, Inc.: Grant Investigator, Research support
Optimer Pharmaceuticals: Investigator and Speaker's Bureau, Research grant and Speaker honorarium
Cubist Pharmaceuticals: Speaker's Bureau, Speaker honorarium

M. Durkin, None

A. Baker, None

D. J. Sexton, None

D. Anderson, None

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