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564 Beyond 30 Days: Are a Substantial Proportion of SSIs Missed by Adhering to a Limited Surveillance Window

Sunday, April 3, 2011
Trinity Ballroom (Hilton Anatole)
Julie Dunn, MPH , Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA
Susan S. Huang, MD, MPH , Division of Infectious Diseases and Health Policy Research Institute, University of California, Irvine School of Medicine, Irvine, CA
Deborah S. Yokoe, MD, MPH , Brigham and Women's Hospital and Harvard Medical School, Boston, MA
Margaret A. Olsen, PhD, MPH , Washington University School of Medicine, Saint Louis, MO
Richard Platt, MD, MS , Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA

Background:  Consistency and completeness of surgical site infection (SSI) surveillance has gained increased importance due to public reporting and potential non-payment rules for facilities that do not meet national benchmarks.  National Healthcare Safety Network (NHSN) SSI surveillance requires a 365-day postoperative surveillance period for procedures involving implants and 30 days for non-implant procedures.  In contrast, the National Surgical Quality Improvement Program (NSQIP) and the Society of Thoracic Surgeons (STS) systems employ a 30-day post-operative surveillance window regardless of implant status.  As the Centers for Medicare & Medicaid Services (CMS) considers possible SSI outcome measures for required reporting, assessment of the completeness of surveillance using a 30-day window may inform the choice of outcome measures.

Objective: To estimate the proportion of SSI following total knee (TKR) and hip replacement (THR), coronary artery bypass graft (CABG) and mastectomy procedures that would be missed using a 30-day surveillance period.

Methods: We analyzed data from four previously reported cohort studies that used a) administrative claims (CABG), b) inpatient antimicrobial- and diagnosis codes (TKR and THR), and c) prospective surveillance (mastectomy) to identify SSI within 365 days of surgery. For CABG, TKR, and THR, we determined the proportion of deep incisional and organ space SSI identified ≤30 and >30 days after surgery (“late-SSI”). For mastectomy, all SSIs were evaluated.

Results: Deep incisional or organ space (DI/OS) SSI rates were 0.6% (27/4,194) for TKR, 1.2% (21/1,691) for THR, and 2.0% (477/23,376) for CABG. Superficial incisional (SI) or deep incisional SSI rates were 6.5% (27/413) for mastectomy-only and 22.3% (73/327) for mastectomy-plus-implant procedures.  DI/OS SSIs identified > 30 days post-procedure accounted for between 24% and 67% of SSI cases for TKR, THR and CABG. SI/DI SSIs identified > 30 days post-procedure accounted for 51% of SSIs resulting from mastectomy and mastectomy-plus-implant procedures (TABLE1).

 

Conclusions: Limiting post-operative surveillance to a 30-day period would lead to under-reporting of approximately one quarter to two-thirds of late-SSI for procedures that we surveyed.  SSI surveillance measures that include longer surveillance periods for these procedures should be considered.

Table 1:

Surgical Procedure

Number of
Procedures

Number of DI/OS SSIs

DI/OS SSI ≤ 30 Days

DI/OS SSI > 30 Days

Mean Days to Onset

Mean Days to Onset

% ≤ 30 Days

of SSI (SD)

% > 30 Days

of SSI (SD)

TKR 

4,194

40

33.3%

15.7(6.9)

66.7%

114(80.9)

THR 

1,691

30

76.2%

19.8(5.2)

23.8%

50(16.7)

CABG 

23,376

958

67.8%

32.1%

Mastectomy only*

413

27*

51.9%

18.3(7.1)

48.1%

108.8(80.4)

Mastectomy plus implant*

327

73*

47.9%

19.5(7.1)

52.1%

83.4(9.4)

* Superficial incisional and Deep incisional SSIs only