690. Use of Medicare Diagnosis and Procedure Codes to Improve Detection of Surgical Site Infections Following Hip Arthroplasty, Knee Arthroplasty, and Vascular Surgery
Session: Poster Abstract Session: Skin, Soft Tissue and Joint Infections
Friday, October 21, 2011
Room: Poster Hall B1
  • Calderwood_IDSA2011_Poster.pdf (489.1 kB)
  • Background: Conventional surveillance of surgical site infections (SSI) is both labor intensive and subject to reporting bias. We evaluated the use of routinely collected electronic health data in Medicare claims to identify SSI following hip arthroplasty, knee arthroplasty, and vascular surgery.

    Methods: We conducted a retrospective cohort study at four hospitals that had been performing prospective SSI surveillance for these procedures. We developed comprehensive lists of ICD-9 and CPT diagnosis and procedure codes to identify possible SSIs. We then screened for these codes in inpatient and outpatient Medicare claims submitted by each hospital on patients ≥65 years old who had undergone one of these procedures during 2007. Each site reviewed full medical records for patients identified by either claims-based surveillance or traditional infection control surveillance looking for CDC/National Healthcare Safety Network (NHSN) criteria for SSI. We assessed the sensitivity of both methods against all chart-confirmed SSIs identified by either method. We also evaluated the positive predictive value of claims-based surveillance.

    Results: The performance of the two SSI detection methods is shown in the table:

    Procedure type

    # of procedures

    Total SSIs identified

    Rate ratio, claims vs traditional

    Either Method

    Traditional surveillance (Sensitivity)

    Claims only (Sensitivity)

    Hip arthroplasty



    3 (21%)

    14 (100%)


    Knee arthroplasty



    4 (57%)

    7 (100%)


    Vascular surgery



    16 (55%)

    29 (100%)


    Claims-based surveillance identified 80% to 270% more SSIs than traditional surveillance, including detection of all previously identified cases. For hip, knee, and vascular surgery, there was a 5-fold, 0-fold, and 1.6-fold increase in detection of deep and organ space infections, respectively. The use of claims-based surveillance to trigger chart review led to confirmation of SSI in 1 out of 3 charts for hip arthroplasty, 1 out of 5 charts for knee arthroplasty, and 1 out of 2 charts for vascular surgery.

    Conclusion: Claims-based SSI surveillance markedly increased the number of SSIs detected following hip arthroplasty, knee arthroplasty, and vascular surgery. It deserves consideration as a more effective approach to identifying potential SSIs.

    Subject Category: N. Hospital-acquired and surgical infections, infection control, and health outcomes including general public health and health services research

    Michael Calderwood, MD1, Allen Ma, PhD2, Yosef Khan, MBBS, MPH3, Margaret Olsen, PhD, MPH4, Dale Bratzler, DO, MPH2, Deborah Yokoe, MD, MPH5, David Hooper, MD6, Kurt Stevenson, MD, MPH3, Victoria Fraser, MD4, Richard Platt, MD MS1 and Susan Huang, MD, MPH7, (1)Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, (2)Oklahoma Foundation for Medical Quality, Oklahoma City, OK, (3)The Ohio State University Medical Center, Columbus, OH, (4)Washington University School of Medicine, St. Louis, MO, (5)Brigham and Women's Hospital, Boston, MA, (6)Massachusetts General Hospital, Boston, MA, (7)UC Irvine School of Medicine, Orange, CA


    M. Calderwood, None

    A. Ma, None

    Y. Khan, None

    M. Olsen, None

    D. Bratzler, None

    D. Yokoe, None

    D. Hooper, None

    K. Stevenson, None

    V. Fraser, None

    R. Platt, None

    S. Huang, None

    Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.