41305. The Value of Clinical Prediction in Repeat Testing with Enzyme Immunoassay for Clostridium difficile
Session: Poster Abstract Session: Medical Student Poster Session
Friday, October 4, 2013
Room: Yerba Buena Ballrooms
Posters
  • National IDSA - EIA testing.pdf (415.5 kB)
  • Background: Enzyme immunoassay (EIA), with sensitivity of 70-80% and specificityof 94%, is the most commonly used diagnostic tool in the diagnosis of Clostridium difficile because of its rapid turnaround time and low cost. Repeat testing with EIA has been a practice among hospitalists to compensate for the low sensitivity but this has been recently questioned. Clinical prediction rules on diagnosis of C. diff with acceptable specificity and sensitivity has recently emerged and may have a role in diagnosis. This study aimed to determine the value of repeat testing in our facility and whether the addition of clinical data can help in clinical decision making.

    Methods: A retrospective chart review of 91 patients with suspected C diff-associated diarrhea (CDAD) who had subsequent testing after an initially negative result was conducted. The primary outcome was positive yield with repeat EIA testing within 7 days of an initial negative test.  Known clinical predictors for C diff, including recent hospitalization, WBC, albumin level,immune-suppression, PPI or H2B use, were also identified in each patient to find out if individually or as a composite they favor repeat testing.

    Results: Ninety three percent (93%) of the subjects were negative, and 7% turned out positive within 7 days after the initial negative test. Of clinical variables examined, no individual variable or even a composite of variables was found to strongly predict positivity after an initial negative test.

    Conclusion: The positivity rate in this study with repeat EIA testing is about three times more common than in reported literature (~1.9-2.5%), and favors repeat testing if EIA remains the only the diagnostic test available.  While clinical prediction may be useful in decision making in the initial diagnosis of CDAD, this study found no role in using it in deciding repeat testing with EIA.

    Lemuel Non, MD1, Jerry Zuckerman, MD2 and Anastasios Dimou, MD3, (1)Einstein Medical Center, Philadelphia, PA, (2)Infectious Diseases, Albert Einstein Medical Center, Philadelphia, PA, (3)Department of Medicine, Einstein Medical Center, Philadelphia, PA

    Disclosures:

    L. Non, None

    J. Zuckerman, None

    A. Dimou, None

    Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 2nd with the exception of research findings presented at the IDWeek press conferences.