320. Variation in use of chronic antibiotic suppression (CAS) for treatment of Staphylococcus aureus prosthetic joint infection (PJI)
Session: Poster Abstract Session: Bone and Joint Infections
Thursday, October 4, 2018
Room: S Poster Hall
  • IDWEEK 2018 - CAS Facility level variation poster_v3.pdf (5.1 MB)
  • Background: The Infectious Diseases Society of America (IDSA) guidelines observed that prescribing CAS for treatment of PJI is an unresolved issue. We aimed to characterize variation in use of CAS while accounting for patient-level factors to identify targets for antimicrobial stewardship in the Veterans Affairs system.  


    Methods: A retrospective cohort study was conducted using data on veterans with a diagnosis of S. aureus PJI between 2003-2015. Patients managed with debridement, 1-stage exchange (OSE), or 2-stage exchange (TSE) were included. Differences in characteristics between any CAS and no CAS treatment (None) were determined by the Mann-Whitney U test for continuous variables and Fisher’s Exact test for dichotomous variables. Generalized linear mixed models were used to calculate the risk standardized measure (observed to expected (O/E) ratio) of a hospital’s CAS use.       

    Results: 944 (75%), 310 (25%), and 11 (<1%) were managed with debridement, TSE, and OSE, respectively among the 1265 included patients. CAS was prescribed in 80% of debridement patients, 49% of TSE patients, and 100% of OSE patients. Patient factors associated with CAS use were different for debridement and TSE [Table]. Risk adjusted models demonstrated greater variability among facilities using CAS after TSE compared with debridement and the overall cohort [Figure].  

    Conclusion: There is substantial variation in use of CAS by patient characteristics for S. aureus PJI across the VHA system. This variation differs between debridement and TSE surgery patients. Further research is warranted to guide CAS recommendations.


    Table Characteristics for overall cohort and by type of surgery





    Patient factors different between Any vs None CAS groups

    Site of PJI




    Body Mass Index (p=0.008)



    Coagulopathy (p=0.03)

    Serum creatinine# (p=0.04)

    Erythrocyte Sedimentation Rate# (p=0.0003)




    Serum creatinine# (p=0.0002)

    Average income$ (p=0.01)


    C-Reactive Protein# (p=0.0003)

    Severity of illness at time of PJI



    White blood cell count#


    Receipt of dialysis# (p=0.0007)


    Receipt of dialysis (p=0.006)



    #After PJI revision surgery and prior to initiation of CAS

    $Year prior to PJI


    Rajeshwari Nair, PhD, MBBS, MPH1,2, Marin Schweizer, PhD2, Kay M. Tomashek, MD, MPH3, Patricia Winokur, MD4, Eli Perencevich, MD, MS, FIDSA, FSHEA1, Yunshu Zhou, MS5 and Michihiko Goto, MD, MSCI2, (1)Iowa City VA Health Care System, Iowa City, IA, (2)Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, (3)Dengue Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention (CDC), San Juan, PR, (4)University of Iowa, Iowa City, IA, (5)Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA


    R. Nair, None

    M. Schweizer, None

    K. M. Tomashek, None

    P. Winokur, None

    E. Perencevich, None

    Y. Zhou, None

    M. Goto, None

    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.