C-reactive protein as a marker of septic shock and outcome in the intensive care unit

Introduction

As an acute phase protein C-reactive protein (CRP) is directly related to the inflammatory response and it has been used to monitor the course of infection. The association of CRP levels and septic shock are not known. In this study we will examine the relationship of CRP levels to septic shock and to the outcome.

Methods

A prospective study on a six-bed ICU of a university hospital and on a five-bed medical ICU of a tertiary care hospital. Data were collected prospectively over a period of 1.5 years. Sixty-eight patients were included in the study. Patient that stayed in the ICU for less than 5 days were excluded from the study, as well as patients that had infection at the time of admission. CRP, APACHE II score, SOFA, WBC, platelets and use of inotropes were recorded on days 1, 3, 6, 9, 12 and 15. Patients were followed up for a septic episode up to day 15 and were followed up to their discharge for outcome. All patients that were included in the study met the ACCP/SCCM consensus criteria for sepsis and septic shock. Serum CRP levels are expressed as mean ± standard deviation.

Results

The group of patients were divided into septic (n = 28) and nonseptic (n = 40). Septic shock showed a strong relationship to CRP levels. Twenty-eight patients (41%) developed septic shock and all these patients had significantly higher CRP levels not only upon admission (13.3 ± 8.9 mg/dl vs 5.2 ± 7.1 mg/dl), but the high values persisted the following days as well. The overall mortality rate was (27.8%). Nonsurvivors had significantly higher CRP levels than survivors. Patients that showed further increase of CRP on day 3 showed a higher mortality rate (64%) when compared with patients that showed a reduction of CRP on day 3 (22%) and remained low. CRP values that remained high (>15 mg/dl) after day 9 were associated with an even higher incidence of death (72%). APACHE II and SOFA scores, leucocyte count and platelets showed no significant relationship to CRP on either groups. Furthermore, APACHE II and SOFA scores were similar for both groups upon admission.

Conclusions

In our ICU elevated CRP values upon admission correlate strongly with increased risk of death. Persistently high CRP values correlate with even poorer outcome. Moreover, CRP is a good marker of septic shock. Overall, persistently high CRP values are associated with longer stay in the ICU, with septic shock, and with higher mortality. Since CRP seems to be a marker of an ongoing inflammatory process, then following the trends of such a marker might help in decision-making for further interventions on septic patients.