Serial procalcitonin levels for predicting prognosis in community-acquired pneumonia.

BACKGROUND AND OBJECTIVE: This study aimed to investigate the usefulness of addition of serial measurements of procalcitonin (PCT) to C-reactive protein (CRP) values and pneumonia severity scores, such as CURB-65 (confusion, urea > 7 mmol/L, respiratory rate ≥ 30 breaths/min, low blood pressure (systolic < 90 mm Hg or diastolic ≤ 60 mm Hg) and age ≥ 65 years) and the Pneumonia Severity Index, and attempted to create and evaluate a new scoring system for predicting mortality risk using the biomarkers and pneumonia severity scores.

METHODS: A total of 365 hospitalized community-acquired pneumonia (CAP) patients in an observational cohort study in which PCT was measured serially from admission to 2-3 days after admission between December 2010 and December 2014 were reviewed retrospectively. PCT and CRP were measured on admission (PCT D1 and CRP D1) and within 48-72 h after admission (PCT D3 and CRP D3).

RESULTS: Twenty-one patients died (5.8%), and 52 patients (14.2%) did not respond to initial therapy. On multivariate analysis, CRP D1 ≥ 100 mg/L (P = 0.002), CURB-65 ≥ 3 (P < 0.001) and PCT D3/D1 ≥ 1 (P < 0.001) were significant predictors of 30-day mortality. Peak CRP (P = 0.02) and PCT D3/D1 ≥ 1 (P = 0.03) were significant predictors of initial treatment failure. Using the new scoring system that defines CRP D1 ≥ 100 mg/L as 2 points, CURB-65 ≥ 3 as 1 point and PCT D3/D1 ≥ 1 as 1 point, in CAP patients with both CRP D1 ≥ 100 mg/L and CURB-65 ≥ 3 on admission, the 30-day mortality rate was 21.8%, and with PCT D3/D1 ≥ 1, it increased to 50.0%.

CONCLUSION: It is useful to add serial measurements of PCT to CRP measurement and assessment of CURB-65 on admission of CAP patients to predict prognosis and initial treatment failure.