A Diagnostic Stewardship Intervention to Improve Utilization of 1,3-β-D-glucan Testing

1,3-β-D-glucan (BDG) is a cell wall component of fungi such as Aspergillus spp., Candida spp., and Pneumocystis jirovecii. BDG assay is used as a screening test to aid early diagnosis of invasive fungal infections (IFI) that are associated with significant morbidity and mortality in immunocompromised patients. The diagnostic performance varies depending on IFI risks among study populations, thus it is important to appropriately select patients with risk factors for IFI to optimize utilization of the BDG test.

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An intervention to improve BDG test utilization was initiated at Truman Medical Center on November 28, 2018. The BDG test order was replaced by a BDG test request. The request was sent to the inbox of an on-call pathology team. Patient information was reviewed and the on-call pathology team called the ordering physician to discuss the case based on the approval algorithm chart. The criteria for BDG test approval were 1) immunocompromised or ICU patient, and 2) on empiric antifungal therapy, or inability to perform specific diagnostic tests such as bronchoscopy. If approved, a BDG test order was immediately processed. Retrospective chart review was conducted for 1 year pre- and post- intervention to obtain demographic, clinical, and laboratory data for 4 patient groups. Group 1 included patients who had BDG tests during pre-intervention period. Group 2 was composed of all patients who had BDG test requests during post-intervention period. Group 2a and 2b were the post-intervention patients with approved and rejected BDG test requests, respectively.

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The number of BDG tests performed per year decreased from 156 pre-intervention to 24 post-intervention. The number of test requests was 65 and 41 of them were rejected which led to $7,380 direct cost savings. There was no significant difference in age or the proportion of immunocompromised and ICU patients between Group 1 and 2. The test positivity rate was significantly higher in Group 2-a compared to Group 1 (45.8 % vs. 25.3%, p=0.038). There was no delay in IFI diagnosis or IFI-related mortality in patients for whom BDG test requests were rejected.

We successfully and safely implemented a diagnostic stewardship intervention for BDG testing and improved test utilization.