Cost effectiveness of pneumococcal urinary antigen in Emergency Department: a pragmatic real-life study.

Community-acquired pneumonia (CAP) is frequent and can be life-threatening. Streptococcus pneumoniae is the main bacteria involved, and is susceptible to penicillin A. Rapid microbiological diagnosis could then help reduce the antimicrobial spectrum. The pneumococcal urinary antigen (PUA) test is fast and easy to perform, but its impact on antimicrobial prescription and cost-effectiveness in emergency departments (ED) is not well known. We performed a pragmatic real life retrospective study in an adult ED to assess its usefulness: proportion of positive results, impact on antimicrobial prescriptions and cost-effectiveness. Over 3 years (from January 1st 2012 to December 31st 2014), 979 PUA tests were reutilized in our ED among 1224 patients who consulted for CAP; 51 (5.2%) were positive. Among them, 10 led to a modification of the antimicrobial treatment, but only 7 (14.3%) were in accordance with the results. The total cost of a PUA test is 27€. As only 7 PUA tests led to appropriate antimicrobial modification, we deemed that 972 had no impact, and the potential cost savings, if the test had not been used, would have been 26,244 € (972 × 27) during 3 years, that is 8748 € per year. Thus, it seems that the PUA test should not be generally used in the ED considering its low rate of positivity and the difficulties for physicians to adapt antibiotic treatment accordingly. This attitude change in utilization would lead to substantial cost savings.