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.