Impact of Procalcitonin Testing on Antibiotic Use in Patients Hospitalized With Community-Acquired Pneumonia: A Multi-Hospital Cohort Study

BACKGROUND: Procalcitonin (PCT) testing may guide antibiotic decisions in community-acquired pneumonia (CAP), but real-world evidence of its impact on antibiotic prescribing in the era of shorter antibiotic courses remains limited. METHODS: We conducted a retrospective cohort study of adults with CAP admitted to the wards of 12 hospitals between November 2022 and January 2025. Primary analyses included: (1) PCT testing rates at admission, (2) the association between PCT testing and duration of antibiotic therapy, and (3) among patients initiated on extended-spectrum antibiotics (ESAs), the relationship between PCT results and early de-escalation. We compared outcomes between PCT-tested and untested patients and between those with low (<0.1 μg/L) vs high (≥0.1 μg/L) PCT values using propensity score overlap weighting to control for potential confounders. RESULTS: Among 17 290 non-intensive care unit (ICU) admissions for CAP, PCT testing was performed for 10 658 patients (59.5%) within 24 hours of admission. After adjustments, PCT testing was associated with shorter antibiotic duration (adjusted mean difference, -0.32 days; 95% confidence interval [CI], -.52 to -.12) but was not significantly associated with ESA de-escalation compared with no PCT testing (hazard ratio, 1.05; 95% CI, .99-1.12). Patients with low PCT values received shorter antibiotic courses compared with those with high values (adjusted mean difference, -0.56 days; 95% CI, -.85 to -.49). CONCLUSIONS: In non-ICU patients with CAP, PCT testing was associated with modest differences in antibiotic duration, primarily when values were low.