2121. Shifting Surgical Site Infection Denominators and Implication on NHSN Reporting
Session: Poster Abstract Session: Healthcare Epidemiology: Surgical Site Infections
Saturday, October 6, 2018
Room: S Poster Hall
Posters
  • SSI denominators ID week 2018 9_25 final.pdf (240.5 kB)
  • Background: Per National Healthcare Safety Network (NHSN) rules, when multiple procedures are performed during a single operation, the operation is counted in the surgical site infection (SSI) denominator of each NHSN surgical procedure category. SSIs, however, are counted only in the highest-ranking procedure category. These rules result in procedures that are ineligible to have an associated SSI being counted in SSI denominators.

    Methods: We analyzed 3 years (1/1/15-12/31/17) of laminectomy and rectal surgery SSI data from hospitals in the Duke Infection Control Outreach Network (DICON) that used ICD procedure codes to assign denominators per NHSN definitions. We compared SSI rates using 2 different denominators: NHSN denominators versus reduced denominators that counted only primary laminectomy and rectal surgery procedures. We calculated rate ratios (RR) to compare the NHSN and adjusted SSI rates for each procedure for all hospitals that reported at least 1 SSI.

    Results: 11 hospitals reported 87 infections following 17,247 laminectomy procedures. The overall SSI rate increased by 44% when only primary procedures were counted in the denominator (RR 1.44); but individual hospital RR ranged from 1.10 to 2.20 (Table 1). 5 hospitals reported 7 SSIs following 740 rectal procedures. The overall SSI rate increased by 143% when only primary procedures were counted in the denominator (RR 2.43), but individual hospital RR ranged from 2.00 to 5.00 (Table 1).

    Conclusion: NHSN’s method for calculating SSI denominators underestimates true SSI rate. The current method particularly impacts procedures that are frequently performed in conjunction with higher-ranking NHSN procedures. Counting only primary procedures in procedure category denominators would provide higher, more accurate SSI rates.

    Table 1. Comparison of SSI rates calculated using adjusted denominators versus NHSN denominators

    Laminectomy Procedures

    Hospital

    Adjusted Rate

    NHSN Rate

    RR

    1

    0.55

    0.50

    1.10

    2

    0.61

    0.53

    1.15

    3

    0.63

    0.55

    1.16

    4

    0.26

    0.22

    1.22

    5

    1.18

    0.90

    1.30

    6

    1.43

    1.06

    1.34

    7

    0.24

    0.18

    1.34

    8

    0.99

    0.70

    1.41

    9

    0.82

    0.46

    1.77

    10

    0.84

    0.41

    2.05

    11

    1.09

    0.50

    2.20

    Overall

    0.72

    0.50

    1.44

    Rectal Surgeries

    Hospital

    Adjusted Rate

    NHSN Rate

    RR

    1

    9.52

    4.77

    2.00

    2

    0.60

    0.27

    2.27

    3

    2.53

    1.07

    2.37

    4

    2.70

    0.81

    3.35

    5

    5.00

    1.00

    5.00

    Overall

    2.30

    0.95

    2.43

    Jessica Seidelman, MD1, Becky Smith, MD2, Kirk Huslage, MSPH, BSN, RN, CIC2, Arthur W. Baker, MD, MPH3, Deverick J. Anderson, MD, MPH, FIDSA, FSHEA4, Daniel Sexton, MD, FIDSA, FSHEA5 and Sarah S. Lewis, MD MPH2, (1)Duke Center for Antimicrobial Stewardship and Infection Prevention, Durham, NC, (2)Infection Prevention and Hospital Epidemiology, Duke University Medical Center, Durham, NC, (3)Division of Infectious Diseases, Duke University School of Medicine, Durham, NC, (4)Duke Infection Control Outreach Network, Duke University Medical Center, Durham, NC, (5)Division of Infectious Diseases, Duke University Medical Center, Durham, NC

    Disclosures:

    J. Seidelman, None

    B. Smith, None

    K. Huslage, None

    A. W. Baker, None

    D. J. Anderson, None

    D. Sexton, None

    S. S. Lewis, None

    Previous Abstract | Next Abstract >>

    Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 3rd with the exception of research findings presented at the IDWeek press conferences.