β-d-Glucan Testing Is Overused in Patients Without Solid Organ/Stem Cell Transplant or Hematologic Malignancies

BACKGROUND: The β-d-glucan (BDG) assay aids in diagnosis of some invasive fungal infections (IFI) in at-risk patients. Due to an increase in the number of BDG tests ordered at Johns Hopkins Hospital in patients not at high risk for IFI, we evaluated the appropriateness of testing and conducted a survey to understand providers’ knowledge about the test. METHODS: From December 2015 to July 2016, we identified inpatients >17 years with at least one BDG test. We did not evaluate patients with solid organ/stem cell transplant or hematologic malignancies as they generally have indications for BDG testing. Using a standard data collection form, one infectious disease (ID) physician reviewed all test for appropriateness; 20% of cases were reviewed by an additional ID physician. Students, housestaff and allied staff from departments of medicine and surgery were surveyed regarding their knowledge of BDG test characteristics including indications and causes of false-positive results. RESULTS: 355 patients with at least one BDG were included. 33% (n = 116) had a risk factor for IFI (e.g., AIDS, immunosuppressing medication, malignancy, total parenteral nutrition, and prolonged ICU stay) although only 13% (n = 48) of these had proved or possible IFI. 49% (n = 173) had no indication for testing. Of these, 4% (n = 8) had inappropriate antifungals started based on BDG results. Being at an intensive care unit or having cirrhosis was associated with inappropriate BDG use (P = 0.03). Most of the 47 clinicians surveyed recognized the utility of BDG in the diagnosis of candidiasis (63%) and Aspergillosis (78%) but only 49% recognized its utility in diagnosis of Pneumocystis. Fifty-two percent identified its lack of utility for diagnosis of Cryptococcus infection but only 44% recognized lack of utility for diagnosing Zygomycetes. The majority of those surveyed were unable to identify causes of false-positive results of the assay. CONCLUSION: In patients without solid organ/stem cell transplant or hematologic malignancies, clinicians ordered the BDG assay in the absence of clinical risk or evidence of IFI in almost 50% of patients. Survey results suggest an incomplete understanding of organisms associated with positive BDG tests. Clinicians must be educated about the correct patient population in which a new test should be used. DISCLOSURES: All authors: No reported disclosures.