Diagnostic markers of infection : comparison of procalcitonin with C reactive protein in critically ill patients

الملخص EN

Although sepsis defines the typical body response to infection, acutely ill patients frequently present signs of sepsis such as fever, tachycardia, hyperventilation, and leukocytosis, even when no infection can be demonstrated.

There is a need for effective and accurate biological or biochemical tests to support, or exclude, the diagnosis of infection as well as its severity In addition to the white blood cell (WBC) count, C-reactive protein (CRP) is currently the most widely used parameter to support the diagnosis of infection.

.

Recently, Procalcitonin (PCT) has been proposed as a marker of infection in critically ill patients; its level is related to the severity of infection.

The present study was conducted to determine the value of plasma PCT concentrations in the diagnosis of infection compared to the traditional marker CRP concentrations, in 100 acutely ill patients divided according to the presence or absence of infection into 2 groups ; infected (80) and non infected(20).

As well as its role in differentiation between bacterial and viral infections.

Infected group was further subclassified into three subgroups; (la) with viral infection, (lb) localized bacterial infection and (Ic) with septic shock.

The procalcitonin samples, (were taken at days 0, 2, 4, 6), measured in batches by immunoluminometric assay (Brahms Diagnostica, Berlin, Germany), and C reactive protein was measured by a routine turbidimetry assay Statistical analysis of our results reveals that both PCT and CRP can highly significant differentiate between infected and non infected groups in all observation days (0, 2, 4 and 6).

Consistently, in all studied groups increasing PCT concentrations (mean) were associated with severity in the whole course of sepsis.

In contrast, CRP did not significantly reflect the different levels of severity of sepsis.

In patients, who survived, peak procalcitonin concentrations during the first two days after admission were a strong predictor of sepsis.

Peak levels also predicted severe cases of septic shock.

Procalcitonin differed significantly across the three categories of infection (p < 0.

001).

Procalcitonin was higher in patients with septic shock compared with all other groups (p < 0.

001).

PCT more rapidly returned to the normal range or decreased to plasma levels slighly above the normal range, whereas CRP remained elevated in a pathological range Admission procalcitonin was significantly higher in patients with septic shock (8.

02 ± 8.

07 ; range 2.

96-31.

29ng / ml, p < 0.

001), compared with localised bacterial infection (2.

0+2.

15; 0.

01-10.

24ng / ml, p > 0.

05), viral infection (1.

65 ± 1.

51 ; 0.

01-6.

22ng / ml, p > 0.

05), and non-infected group(0.

22 ± 0.

19; 0.

01-0.

62ng / ml).

Admission CRP was significantly higher in patients with septic shock (103±25.

8; range 36-138mg / L ;P < 0.

01), and significant increase compared with localised bacterial infection (86.

7 ±36.

9; 20-148 mg / L ; p<0.

05), and a non significant difference in group of viral infection (56.

1 ± 24.

0; 20-109 mg/L ; p > 0.

05), and non-infected controls (59.

1±28.

6; 22.

0-110mg / L ; p>0.

05).

As well as regarding the sixth day results, they reveal the same conclusion, Area under the ROC curve was 0.

924 for procalcitonin, and 0.

753 for C reactive protein.

Cut off concentrations for optimum prediction of septic shock were: procalcitonin > 20 ng/ml and C reactive protein >150 mg / L.

Admission procalcitonin concentration > 1 ng / ml identified all patients with bacterial infection.

In conclusion in critically ill patients the admission procalcitonin concentration is a better diagnostic marker of infection than C reactive protein.

A procalcitonin concentration of 1 ng / ml might be "useful in ■differentiating severe life-threatening bacterial -infection from--loealised and viral disease in critically ill patients.

C reactive protein did distinguish septic shock from localised bacterial and viral infection (p > 0.

05).

severe cases of septic shock.

Procalcitonin differed significantly across the three categories of infection (p < 0.

001).

Procalcitonin was higher in patients with septic shock compared with all other groups (p < 0.

001).

PCT more rapidly returned to the normal range or decreased to plasma levels slighly above the normal range, whereas CRP remained elevated in a pathological range Admission procalcitonin was significantly higher in patients with septic shock (8.

02 ± 8.

07; range 2.

96-31.

29ng / ml, p < 0.

001), compared with localised bacterial infection (2.

0 ± 2.

15; 0.

01-10.

24ng / ml, p > 0.

05), viral infection (1.

65+ 1.

51 ; 0.

01-6.

22ng / ml, p > 0.

05), and non-infected group (0.

22 ± 0.

19; 0.

01-0.

62ng / ml).

Admission CRP was significantly higher in patients with septic shock (103 ± 25.

8; range 36-138mg / L ;P < 0.

01), and significant increase compared with localised bacterial infection (86.

7±36.

9; 20-148 mg / L;p < 0.

05), and a non significant difference in group of viral infection (56.

1 ± 24.

0; 20-109 mg / L ; p> 0.

05), and non-infected controls (59.

1± 28.

6; 22.

0-110mg / L;p > 0.

05).

As well as regarding the sixth day results, they reveal the same conclusion, Area under the ROC curve was 0.

924 for procalcitonin, and 0.

753 for C reactive protein.

Cut off concentrations for optimum prediction of septic shock were: procalcitonin >20ng/ml and C reactive protein >150mg/L.

Admission procalcitonin concentration > 1 ng/ml identified all patients with bacterial infection.

In conclusion in critically ill patients the admission procalcitonin concentration is a better diagnostic marker of infection than C reactive protein.

AprocaIcite-riiiVCt > ncenfra*ift5n dfl ng / ml might be useful in differentiating severe life threatening bacterial infection from localised and viral disease in critically ill patients.

C reactive protein did distinguish septic shock from localised bacterial and viral infection (p > 0.

05)