Use of Routine Complete Blood Count Results to Rule Out Anaplasmosis Without the Need for Specific Diagnostic Testing

Sarah E. Turbett, Melis N. Anahtar, Vikram Pattanayak, Marwan M. Azar, K. C. Coffey, George Eng, Joseph W. Rudolf, Kent B. Lewandrowski, Jason Baron, Eric S. Rosenberg, John A. Branda

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Background: Anaplasmosis presents with fever, headache, and laboratory abnormalities including leukopenia and thrombocytopenia. Polymerase chain reaction (PCR) is the preferred diagnostic but is overutilized. We determined if routine laboratory tests could exclude anaplasmosis, improving PCR utilization. Methods: Anaplasma PCR results from a 3-year period, with associated complete blood count (CBC) and liver function test results, were retrospectively reviewed. PCR rejection criteria, based on white blood cell (WBC) and platelet (PLT) counts, were developed and prospectively applied in a mock stewardship program. If rejection criteria were met, a committee mock-refused PCR unless the patient was clinically unstable or immunocompromised. Results: WBC and PLT counts were the most actionable routine tests for excluding anaplasmosis. Retrospective review demonstrated that rejection criteria of WBC ≥11 000 cells/μL or PLT ≥300 000 cells/μL would have led to PCR refusal in 428 of 1685 true-negative cases (25%) and 3 of 66 true-positive cases (5%) involving clinically unstable or immunocompromised patients. In the prospective phase, 155 of 663 PCR requests (23%) met rejection criteria and were reviewed by committee, which endorsed refusal in 110 of 155 cases (71%) and approval in 45 (29%), based on clinical criteria. PCR was negative in all 45 committee-approved cases. Only 1 of 110 mock-refused requests yielded a positive PCR result; this patient was already receiving doxycycline at the time of testing. Conclusions: A CBC-based stewardship algorithm would reduce unnecessary Anaplasma PCR testing, without missing active cases. Although the prospectively evaluated screening approach involved medical record review, this was unnecessary to prevent errors and could be replaced by a rejection comment specifying clinical situations that might warrant overriding the algorithm.

Original languageEnglish (US)
Pages (from-to)1215-1221
Number of pages7
JournalClinical Infectious Diseases
Issue number6
StatePublished - Mar 3 2020

Bibliographical note

Funding Information:
Potential conflicts of interest. M. N. A. has equity as a cofounder of Day Zero Diagnostics. J. A. B. has received research support from Zeus Diagnostics, Immunetics, Alere, DiaSorin, bioMérieux, the Bay Area Lyme Foundation, the Lyme Disease Biobank Foundation, and the National Institute of Allergy and Infectious Diseases (award number 1R21AI119457-01) for other research projects and has served as consultant to DiaSorin, Roche, and T2 Biosystems. J. B. works part-time as a computational pathology consultant for Roche Diagnostics in addition to his academic role. He has also received grant support, paid to his institution, from IBM. E. S. R. has served as a consultant for T2 Biosystems and is an advisor with equity for Total Biocidal Solutions. All other authors report no potential conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

Publisher Copyright:
© 2019 The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail:


  • Anaplasma phagocytophilum
  • PCR
  • diagnosis
  • stewardship
  • utilization management


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