Real-world use of procalcitonin for antimicrobial stewardship in severe community-acquired pneumonia

BACKGROUND: Real-world evidence is limited regarding the use and impact of procalcitonin (PCT) on antibiotic duration in severe community-acquired pneumonia (SCAP) patients. METHODS: A retrospective cohort study of adult patients with SCAP (defined by modified American Thoracic Society [ATS] criteria) to 12 hospitals between November 2022 and June 2025. We analyzed clinical characteristics and estimated the association between PCT testing within 24 hours of hospital admission and antibiotic duration, and between low (<.5 µg/L) and high (≥.5 µg/L) PCT values and antibiotic duration. Clinical stability was determined based on ATS criteria (temperature <100 °F with ≤1 sign of instability within 24 hours of admission). RESULTS: Among 1,553 SCAP admissions, 325 (21%) were clinically stable on admission and 924 patients (59.5%) had PCT testing within 24 hours; 452 (48.9%) of PCTs were low. Clinical stability was not associated with testing. PCT testing was associated with fewer antibiotic days (mean 6.9 vs 7.4 days adjusted mean difference, -.5 days, 95% CI: -.8, -.3), particularly in stable (mean 6.6 vs 7.3 days, adjusted mean difference, -.8 days, 95% CI: -1, -.1) versus unstable patients (mean 7.2 vs 7.5 days, adjusted mean difference, -.4 days, 95% CI: -.8, -.05). Low PCT values were associated with shorter antibiotic durations than high values (mean 6.5 vs 7.6 days, adjusted mean difference, -1.1 days, 95% CI: -1.9, -.3). CONCLUSIONS: PCT testing was associated with shorter antibiotic duration, especially among stable patients, but was performed without regard to clinical stability. Reserving PCT testing for stable patients may improve efficiency.