164. Medicare Beneficiaries are Often Readmitted Due to Inadequate Treatment of Infection or Adverse Antimicrobial Events
Session: Oral Abstract Session: Infectious Diseases Practice Challenges
Friday, October 21, 2011: 11:30 AM
Room: 151AB
Background: Adverse effects of antimicrobial therapy are a common reason for ambulatory visits, but there is limited information on its impact on hospital readmission. The purpose of this study was to characterize patients readmitted to the hospital within 30 days due to inadequate or inappropriate treatment of infection (ITI) or adverse antimicrobial events (AAEs).

Methods: An observational retrospective cohort study of Medicare beneficiaries at an 850 bed academic tertiary care center was performed. Cohort patients were exposed to an antimicrobial during a hospital admission in 2010 and were readmitted to the hospital within 30 days. Electronic medical records were examined for both admissions. The primary reason for readmission was determined and further categorized if associated with an ITI or AAE. ITI was defined as inadequate source control, bug-drug mismatch, patient nonadherence to therapy, or inadequate choice or duration of therapy; AAE as Clostridium difficile infection (CDI), hypersensitivity reaction, acute renal failure or pancreatitis, or other adverse effect. Exclusions were 1st hospitalization due to chemo- or radiation therapy, nonemergent dialysis, rehabilitation, childbirth; or resulting in death.

Results: 12,037 Medicare patients were admitted during the study period and 8,117 (67.4%) received an antimicrobial (mean age 60.8yrs, LOS 7.0 days, and duration of antimicrobial 5.6 days). 7,088 patients remained after exclusions, and of these, 505 (7.1%) were readmitted within 30 days (compared to 7.7% of those who did not receive an antimicrobial). Those due to due to an ITI or AAE are shown (Table).

Table:  82 (16.2%) of 505 30-Day Readmissions Due to an ITI or AAE


Number (%)


Number (%)


71 (14.1)


11 (2.1)

    Inadequate source control

41 (8.1)


 3 (0.5)

    Nonadherence to antimicrobial

15 (2.9)


 4 (0.6)

    Bug-drug mismatch

10 (1.9)

   Renal failure

 1 (0.1) 

    Inadequate duration of therapy

  5 (0.9)


 1 (0.1)




 2 (0.2)

Conclusion: A greater proportion of patients received an antimicrobial during their hospitalization than previously reported. Readmission frequently occurs due to an ITI or AAE. Many of these could be addressed through education, consultation, and systems improvements.

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

Vera Luther, MD1, Hyun Yoon, MD2, Christopher Ohl, MD1, Kevin High, MD, MS1, Robert Hamm, PhD3 and Jeff Williamson, MD4, (1)IM-Section on Infectious Diseases, Wake Forest School of Medicine, Winston-Salem, NC, (2)Wake Forest School of Medicine, Winston-Salem, NC, (3)University of Oklahoma Health Sciences Center, Oklahooma City, OK, (4)IM-Gerontology and Geriatrics, Wake Forest School of Medicine, Winston-Salem, NC


V. Luther, Atlantic Philanthropies (USA), Inc., the Infectious Diseases Society of America, the John A. Hartford Foundation, Inc., and the Association of Specialty Professors: Grant Investigator, Research grant

H. Yoon, None

C. Ohl, Optimer: Scientific Advisor, Consulting fee
Ortho-McNeil: , Speaker honorarium
Pfizer: Speaker's Bureau, Speaker honorarium
BD-Gene Ohm: Consultant, Consulting fee

K. High, None

R. Hamm, None

J. Williamson, None

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