Mid-regional proadrenomedullin: An early marker of response in critically ill patients with severe community-acquired pneumonia?

Abstract

Background: Mid-regional proadrenomedullin (MR-proADM) is a novel biomarker with potential prognostic utility in patients with community-acquired pneumonia (CAP). Purpose: To evaluate the value of MR-proADM levels at ICU admission for further severity stratification and outcome prediction, and its kinetics as an early predictor of response in severe CAP (SCAP). Materials and methods: Prospective, single-center, cohort study of 19 SCAP patients admitted to the ICU within 12 h after the first antibiotic dose. Results: At ICU admission median MR-proADM was 3.58 nmol/l (IQR: 2.83–10.00). No significant association was found between its serum levels at admission and severity assessed by SAPS II (Spearman's correlation = 0.24, p = 0.31) or SOFA score (SOFA < 10: <3.45 nmol/l vs. SOFA ≥ 10: 3.90 nmol/l, p = 0.74). Hospital and one-year mortality were 26% and 32%, respectively. No significant difference in median MR-proADM serum levels was found between survivors and non-survivors and its accuracy to predict hospital mortality was bad (aROC 0.53). After 48 h of antibiotic therapy, MR-proADM decreased in all but 5 patients (median −20%; IQR −56% to +0.1%). Its kinetics measured by the percent change from baseline was a good predictor of clinical response (aROC 0.80). The best discrimination was achieved by classifying patients according to whether MR-proADM decreased or not within 48 h. No decrease in MR-proADM serum levels significantly increased the chances of dying independently of general severity (SAPS II-adjusted OR 174; 95% CI 2–15,422; p = 0.024). Conclusions: In SCAP patients, a decrease in MR-proADM serum levels in the first 48 h after ICU admission was a good predictor of clinical response and better outcome. Keywords: Proadrenomedullin, Biomarkers, Severe community acquired pneumonia, Outcome, Critically ill patients