Clinical relevance of procalcitonin and C-reactive protein as infection markers in renal impairment: a cross-sectional study

INTRODUCTION Although the clinical application of procalcitonin (PCT) as an infection marker in patients with impaired renal function (estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m(2)) has been increasing recently, it is unclear whether PCT is more accurate than C-reactive protein (CRP). We investigated the clinical value of CRP and PCT based on renal function. METHODS From November 2008 to July 2011, a total of 493 patients who simultaneously underwent CRP and PCT tests were enrolled. The area under the receiver operating characteristic (ROC) curve and characteristics of both markers were analyzed according to infection severity and renal function. RESULTS In patients with impaired renal function, the area under the ROC curve was 0.876 for CRP and 0.876 for PCT. In patients with infection, CRP levels differed depending on whether the infection was localized, septic, or severely septic, whereas PCT levels were higher in patients with severe sepsis or septic shock. In patients without infection, CRP did not correlate with eGFR, while PCT was negatively correlated with eGFR. CONCLUSION This study demonstrates that CRP is accurate for predicting infection in patients with impaired renal function. The study suggests that in spite of its higher cost, PCT is not superior to CRP as an infection marker in terms of diagnostic value.