Procalcitonin May be a Potential Biomarker for Distinguishing Bacterial Infection from Disease Activity in Febrile Patients with Systemic Lupus Erythematosus

Abstract

Objective: To investigate the utility of procalcitonin (PCT) in febrile patients with systemic lupus erythematosus (SLE). Methods: Serum PCT levels were measured with enzyme-linked fluorescent assay and C-reactive protein (CRP) with nephrometry in 49 febrile patients with SLE. Serum PCT levels were measured in 20 healthy people for normal control. The predictive values of PCT and CRP for detecting bacteria infection were evaluated by receiver operating characteristic (ROC) curves. Results: Enrolled patients included 30 patients without clinical evidence of infection favoring diagnosis of SLE disease flare, and 19 patients with bacterial infection. In febrile patients with SLE, PCT level was significantly higher in bacterial infection group compared with SLE disease flare group (median 7.11 ng/mL vs. 0.06 ng/mL, p＜0.001), especially in patients with sepsis and septic shock. The most appropriate cutoff value of PCT was 0.74 ng/mL and CRP 16.1 mg/dL for predicting bacterial infection in febrile patients with SLE. The sensitivity (89.5%) and specificity (100%) of the PCT level for predicting bacterial infection were superior to those of CRP. Conclusion: Our results suggest that serum PCT level could be used as an additional biomarker for timely differential diagnosis between bacterial infection and disease flare in febrile patients with SLE.