643 - Trends, outcomes and cost analysis of Streptococcus urinary antigen testing.

Background: Streptococcus pneumoniae urinary antigen (SUAg) testing detects the capsular polysaccharide of S. pneumoniae; which has a sensitivity and specificity of about 75% and 95%, respectively. IDSA/ATS guidelines recommend empirically covering those who present with community acquired pneumonia (CAP) for common pathogens including S. pneumoniae. These guidelines also recommend against routinely performing SUAg testing in adults with CAP unless the presentation is severe. However, the guidelines acknowledge that this a conditional recommendation based on a low quality of evidence. This study aims to investigate the utility of testing patients with pneumonia for S. pneumoniae and the economic burden.

Methods: We performed a retrospective study of all patients who received the SUAg test at University of Mississippi Medical Center (UMMC) from January 3, 2013 to December 31, 2019. Patient Cohort Explorer was used to obtain de-identified patient data from EPIC. We obtained the number of encounters and patients on whom the SUAg test was performed. Coding and billing offices provided the self pay cost of $101.37 per SUAg test in 2019 USD.

Results: The SUAg was ordered 2,507 times with 105 (4.18%) total positives results. Age range was 1 to 89 years with a median age of 57 years for ordering the test. 136, 256, 314, 419, 433, 382, 566 SUAg tests were ordered respectively from 2013 to 2019. 59% of the positive results were in female patients while 54% percent of the negative results were in male patients. Current every day smokers were more likely to test positive (29% versus 18% negative). Median length of stay was longer for a negative test (6 days versus 5 days). 16% of the patients with a positive result expired compared to 10.5% with a negative result.
Over the study period, 2,507 tests cost an estimated $254,134.59 using the 2019 pricing. Therefore, approximately $2420.32 was spent in testing to identify each positive result. 

Conclusion: With low positive rate and Streptococci pneumonia that is already covered with empirical antibiotics, we recommend following the current ATS/IDSA guidelines and order the test in select patients as recommended, in efforts to reduce diagnostic burden and health care costs. However a positive result showed a decreased length of stay and higher mortality.