The time course of blood C-reactive protein concentrations in relation to the response to initial antimicrobial therapy in patients with sepsis

Background: C-reactive protein (CRP) may be a useful marker of sepsis but its use in the evaluation of response to therapy remains poorly defined. The aim of this study was to define the time course of CRP levels in septic patients according to their response to initial antimicrobial treatment, and to search for possible correlations between CRP levels and other clinical and biological variables. Patients and Methods: This prospective, observational, multicenter study included all critically ill patients with sepsis admitted to two medico-surgical departments of intensive care in Brussels, Belgium during a 5-month period. CRP levels and standard clinical and biological variables were measured daily from the day of sepsis diagnosis until death, transfer to the general floor, or the seventh day, whichever came first. Patients were divided into three groups according to their clinical course: group 1 - patients with a favorable response to initial antibiotic therapy; group 2 - patients who required a change in antibiotic therapy; group 3 patients who needed a procedure to control the infection. Results: CRP concentrations decreased more rapidly and to a greater degree in group I than in group 2 patients (p = 0.001). An increase in CRP of at least 2.2 mg/dl in the first 48 h was associated with ineffective initial antibiotic therapy with a sensitivity of 77% and a specificity of 67%. No correlation was found between CRP levels and other clinical and biological variables. Conclusion: Changes in CRP levels over the first 48 h of therapy can help to evaluate the response to initial antimicrobial therapy in septic patients.