Discussion

Pneumococcal urinary antigen testing demonstrated frequently negative results and infrequently altered antibiotic management, which is consistent with prior studies reporting low PUAT positivity rates and limited impact on antimicrobial prescribing. ^{Reference Troy, Wong and Barnes1,Reference Bellew, Grijalva and Williams2,Reference Schoepflin and Lubinski5,Reference Athlin, Magnuson, Spindler, Hedlund, Strålin and Nauclér7} Appropriate ordering remained below 25% throughout the study period and was not significantly improved following either intervention. However, systemwide PUAT utilization decreased from approximately 509 tests per month during phase 1 to 193 tests per month during phase 3, suggesting that the interventions reduced overall testing volume, representing a diagnostic stewardship benefit, without improving guideline-concordant ordering. Therapy modification following positive PUAT results occurred infrequently, resulting in only 20 days of atypical antibiotic therapy avoided among 300 reviewed patients. While PUAT did not eliminate empiric atypical antibiotic exposure, it modestly reduced the duration of therapy in a small number of patients.

Similar findings have been reported by Falguera et al., who observed no clinical or economic benefit of PUAT-guided targeted therapy compared with empiric treatment, although antibiotics were narrowed in some patients. ^{Reference Falguera, Schoenenberger and Ruiz-González3} More recently, Davis et al evaluated 1,428 PUATs and found that only a single test resulted in a change in antimicrobial therapy, ultimately leading their institution to discontinue routine PUAT ordering. ^{Reference Davis, McCreary and Trzebucki4} Our findings similarly demonstrated limited clinical impact despite substantial test utilization, further supporting consideration of PUAT removal as a diagnostic stewardship strategy.

Limitations include the low PUAT positivity rate, the potential for antibiotic decision-making to have been influenced by unmeasured clinical factors not captured in the data set, and seasonal variation in respiratory illness that may have influenced PUAT ordering across study phases. Additionally, this project was retrospectively designed, which relied on electronic health record documentation and was conducted within a single health system. Given PUAT’s low opportunity to meaningfully alter care pathways and minimal clinical impact when positive, these findings support reconsideration of routine PUAT availability and suggest its removal as an orderable test may be appropriate within diagnostic stewardship frameworks.