Diagnostic value of procalcitonin and CRP in critically ill patients admitted with suspected sepsis

BACKGROUND Identifying early markers of septic complications can aid in the diagnosis and therapeutic management of hospitalized patients. In this study, the utility of procalcitonin (PCT) vs. C-reactive protein (CRP) as early markers of sepsis was compared. METHODS A series of 2,697 consecutive blood samples was collected from hospitalized patients and serum PCT and CRP levels were measured. Patients were categorized by PCT level as follows: < 0.05 ng/ml, 0.05-0.49 ng/ml, 0.5-1.99 ng/ml, 2-9.99 ng/ml, and > 10 ng/ml. Diagnostic utility was analyzed by receiver operating characteristic (ROC) curves. RESULTS Mean CRP levels varied among the five PCT categories at 0.31 ± 2.87, 5.65 ± 6.26, 13.78 ± 8.01, 12.15 ± 10.16, and 17.77 ± 10.59, respectively (P < 0.05). PCT and CRP differed between positive and negative blood culture groups (PCT: 15.9 vs. 4.78 mg/dl; CRP: 11.5 ng/ml vs. 9.57 ng/ml; P < 0.05). The areas under the ROC curves (PCT, 95% confidence interval [CI]: 0.743, range: 0.698-0.789 at a threshold of 0.5 ng/ml; CRP, 95% CI: 0.540, range: 0.478-0.602 at a threshold of 8 mg/l) differed for PCT and CRP (P < 0.05). CONCLUSIONS Therefore, PCT is a reliable marker for sepsis diagnosis and is more relevant than CRP in patients with a positive blood culture. These findings can be useful for the treatment of critically ill sepsis patients.