90. Incidence and Risk Factors for Inappropriate Use of Non-culture Based Fungal Assays: Implication for Diagnostic Stewardship

BACKGROUND: Culture-based diagnostic tests are the gold standard for diagnosing invasive fungal diseases (IFDs). Because these tests have low sensitivity, non-culture-based fungal assays (NCBFAs) have been used increasingly to help diagnose IFDs. However, little is known about inappropriate use of NCBFAs. We aimed to investigate inappropriate use of NCBFAs in a tertiary academic hospital in Tokyo, Japan. METHODS: This retrospective cohort study included all patients who underwent testing with beta-D glucan (BDG) between January and March 2018, or galactomannan antigen (GMA) or cryptococcal antigen (CRAG) between January and June 2018. Patients who had received hematopoietic stem cell or solid organ transplantations were excluded. Appropriateness was assessed according to the previously published study. We compared patients with appropriate and inappropriate use of NCBFAs. Risk factors for inappropriate use were evaluated using multivariate logistic regression analysis. RESULTS: Of 1,140 patients (BDG, 1,009; GMA 273; CRAG, 310) who underwent tests, 470 patients (BDG, 394; GMA, 138; CRAG, 164) were included in this study. Four hundred thirty-eight patients (93.2%) were aged 18 or older. About 80% of NCBFAs (BDG, 334 patients [74.8%]; GMA, 117 patients [74.8%]; CRAG, 146 patients [89.0%]) were deemed inappropriate. The factors associated with inappropriate NCBFAs use included specialties of ordering physicians, risk factors for fungal infections, and recommendation from infectious disease physicians (Table). Sixty-four patients (13.6%) underwent three inappropriate NCBFAs simultaneously. Furthermore, during the study period, 408 patients (35.8%) with inappropriate NCBFAs underwent the same assays repeatedly during the study period; 643 times for BDG, 163 times for GMA, and 192 times for CRAG. The Factors Associated with Inappropriate Use of Non-Culture Based Fungal Assays [Image: see text] CONCLUSION: We found a large proportion of NCBFAs were deemed inappropriate and it was mostly driven by ordering physicians who generally care for transplant patients. Because inappropriate use of NCBFAs could lead to additional inappropriate tests and treatment with substantial costs to patients and health systems, diagnostic stewardship targeting NCBFAs is urgently needed. DISCLOSURES: All Authors: No reported disclosures