2175. Diagnostic Utility of Pneumococcal Urinary Antigen Assay in Clinical Practice: a Retrospective Study in a Community Hospital in Evanston, Illinois

BACKGROUND: While the pneumococcal urine antigen test (PUAT) is a validated tool for diagnosing pneumonia, recent evidence suggested lower sensitivity than expected (approximately 60-65%) and limited impact on clinical outcomes. A lack of clinical indicators for a positive test result and the absence of clear recommendations based on high-quality evidence create grounds for potential test misuse in real practice. METHODS: We performed a Workbench report to retrieve individual orders of Streptococcus pneumoniae urine antigen test (BinaxNOW(TM)) from our community hospital in Evanston, Illinois, between January 1, 2011, and December 31, 2021. We then identified patients with or without clinical pneumonia based on McGeer criteria: new infiltrates on chest x-ray plus cough, shortness of breath, oxygen saturation < 94%, or respiratory rate ≥ 25 plus fever, leukocytosis, or altered mental status. RESULTS: Among 8,110 individuals tested for PUAT, only 273 positive results were identified (3.36%); of those, 83 (30.4%) did not meet criteria for clinical pneumonia (Figure 1). The median age of patients in a group with clinical pneumonia and without was 67 and 69 years, respectively. The prevalence of diabetes mellitus, COPD/asthma, and immunosuppression was not statistically significant between groups (Table 1). The signs and symptoms are presented in Table 2.S. pneumoniae was cultured in only 13.9% of cases in patients with clinical pneumonia, which correlates with the known sensitivities of this test (Table 3). More ICU admissions and NIPPV use were noted in patients with clinical pneumonia (p = 0.04 each). However, there was no difference in the use of antibacterial therapy among the two groups (p = 0.83), mechanical ventilation rates (p = 0.2), and length of hospital stay (p = 0.2) (Table 4). The positive predictive value of PUAT was 69% in our study (Table 5). [Figure: see text] [Figure: see text] [Figure: see text] CONCLUSION: Our study demonstrated a low positivity rate of PUAT despite a large sample size and a significant proportion of positive test results in patients without clinical pneumonia. The widespread use of PUAT should be carefully reconsidered and applied only to a selected category of patients. Such a strategy will reduce the discrepancy between current guidelines and real-world care patterns and provide an additional benefit of cost-effectiveness. [Figure: see text] [Figure: see text] [Figure: see text] DISCLOSURES: All Authors: No reported disclosures.