526. An EMR-based diagnostic stewardship intervention for GI mPCR aimed at reducing inappropriate C. difficile tests
Session: Poster Abstract Session: Healthcare Epidemiology: Updates in C. difficile
Thursday, October 4, 2018
Room: S Poster Hall
  • ID week inappropriate c diff tests_poster_final final.pdf (685.5 kB)
  • Background: Diagnostic stewardship is an emerging tool that can be used to prevent overuse of diagnostics.  Because GI mPCR (GI multiplex PCR panel) tests can be ordered on formed stool, the test has lower pre-test probability for C. diff infection than traditional singleplex PCR.  Furthermore, after 48hrs of admission, most other targets on the GI mPCR are no longer clinically relevant. Any C. diff testing on inappropriate specimens may increase the rate of Lab ID events (positive C. diff tests after 3 days of admission) without improving detection of true infections.

    Methods: In Jan 2018, our 700-bed academic medical center implemented an informatics-based intervention that restricted ordering of the GI mPCR to the first 48hrs of hospitalization. After 48hrs, providers were required to contact microbiology to request an exception (see Fig 1).  Singleplex PCR testing for C diff was available throughout admission. Orders for the GI mPCR test require the provider to note whether the patient had >3 loose stools in the previous day.  Statistical analysis performed with STATA software.

    Results: 282 late (after 48hrs of admission) GI mPCR tests were ordered in the 104 days before restriction and 210 late tests were ordered in the 104 days after. Late GI mPCR tests (before and after restriction) resulted in diagnoses other than C. diff less than 5% of the time (20 of 492 tests). 11.7% (24 of 210) of late GI mPCR tests were ordered for patients who did not have >3 loose stools in the previous day.  Prior to restriction, 15% (41 of 282) of Lab ID events from GI mPCR were for patients who had already tested positive for C. diff earlier in the same admission.  Following the intervention, there was a decreased proportion of GI mPCR tests that were positive for C. diff (from 14.5% to 11.3%, p=0.26), as well as a significantly decreased rate of Lab ID events detected by GI mPCR, from 7.2/10000 patient days to 4.0/10000 patient days (p=0.01).

    Conclusion:   Accurate diagnosis of C. diff infection is important for treatment and prevention efforts, yet this data show that many rapid GI mPCR tests are inappropriately ordered on patients who may not have loose stools and who are unlikely to have an alternate diagnosis. EMR-based restriction on the GI mPCR ordering time reduced Lab ID events of C. diff infection without missing important alternate diagnoses.

    Fig 1.


    Margaret E. Newman, MD1, Emily Landon, MD1, Allison Bartlett, MD, MS2, Rachel Marrs, DNP, RN, CIC3, Alexandra Seguin, BSN, RN3, Cynthia Murillo, M(ASCP), CIC3, Kathleen G. Beavis, MD4 and Jessica P. Ridgway, MD, MS5, (1)Infectious Diseases and Global Health, The University of Chicago Medicine, Chicago, IL, (2)Department of Pediatrics, Section Infectious Disease, University of Chicago / Comer Children Hospital, Chicago, IL, (3)Infection Control Program, The University of Chicago Medicine, Chicago, IL, (4)Department of Pathology, The University of Chicago, Chicago, IL, (5)Section of Infectious Diseases and Global Health, University of Chicago Medicine, Chicago, IL


    M. E. Newman, None

    E. Landon, None

    A. Bartlett, None

    R. Marrs, None

    A. Seguin, None

    C. Murillo, None

    K. G. Beavis, None

    J. P. Ridgway, None

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