Predicting intensive care need among adults with community-acquired pneumonia (CAP) remains challenging.
Using a multicenter prospective cohort study of adults hospitalized with CAP, we evaluated the association of serum procalcitonin concentration at hospital presentation with the need for invasive respiratory and/or vasopressor support (IRVS) within 72 hours. Logistic regression was used to model this association, with results reported as the estimated risk of IRVS for a given procalcitonin concentration. We also assessed whether the addition of procalcitonin changed the performance of established pneumonia severity scores, including the pneumonia severity index and American Thoracic Society minor criteria, for prediction of IRVS.
Of 1770 enrolled patients, 115 (6.5%) required IRVS. Using the logistic regression model, procalcitonin concentration had a strong association with IRVS risk. Undetectable procalcitonin (<0.05 ng/ml) was associated with a 4.0% (95% CI: 3.1%, 5.1%) risk of IRVS. For concentrations <10 ng/ml, procalcitonin had an approximate linear association with IRVS risk; for each 1 ng/ml increase in procalcitonin, there was a 1-2% absolute increase in the risk of IRVS. With a procalcitonin concentration of 10 ng/ml, the risk of IRVS was 22.4% (95% CI: 16.3%, 30.1%) and remained relatively constant for all concentrations > 10 ng/ml. When added to each pneumonia severity score, procalcitonin contributed significant additional risk information for prediction of IRVS.
Serum procalcitonin concentration was strongly associated with the risk of requiring IRVS among adults hospitalized with CAP and is potentially useful for guiding decisions about intensive care unit admission.