Usefulness of Early C-Reactive Protein Kinetics in Response and Prognostic Assessment in Infected Critically III Patients: An Observational Retrospective Study

Introduction: The ideal biomarker to assess response and prognostic assessment in the infected critically ill patient is still not available. The aims of our study were to analyze the association between early C-reactive protein kinetics and duration and appropriateness of antibiotic therapy and its usefulness in predicting mortality in infected critically ill patients. Material and Methods: We have carried out an observational retrospective study in a cohort of 60 patients with community-acquired pneumonia, aspiration pneumonia and bacteremia at an intensive care unit. We have collected C-reactive protein consecutive serum levels for eight days as well as duration and appropriateness of initial antibiotic therapy. C-reactive protein kinetic groups were defined based on the levels at days 0, 4 and 7. With a follow-up of one year, we have evaluated mortality at different time-points. Results: We have obtained three different C-reactive protein kinetic groups from the sample: fast response, delayed but fast response and delayed and slow response. We did not find statistically significant associations between C-reactive protein kinetics and early (intensive care unit, hospital and 28-days) or late (six months and one year) mortality and antibiotic therapy duration (p > 0.05). Although there were no statistically significant differences between the appropriateness of antibiotic therapy and the defined groups (p = 0.265), no patient with inappropriate antibiotic therapy presented a fast response pattern. Discussion: Several studies suggest the importance of this protein in infection. Conclusion: Early C-reactive protein kinetics is not associated with response and prognostic assessment in infected critically ill patients. Nevertheless, a fast response pattern tends to exclude initial inappropriate antibiotic therapy.