What is Abnormal? The Utility of C-Reactive Protein as a Marker of Sepsis Post Major Urological Surgery

Abstract

Background: C-reactive protein (CRP) is an acute phase reactant released in response to cell injury of any cause. A rise in CRP in the immediate postoperative period may be misattributed to surgical tissue damage and not to infection, posing a diagnostic challenge for the clinician. We have evaluated its performance as a marker of infective complications following major urological surgery. Materials and Methods:We reviewed all patients undergoing major urological surgery between March-December 2014. Data including operation, route, Charlson index, post-operative infection, and CRP measurements were recorded. We plotted receiver operating characteristic curves to evaluate the utility of CRP as a marker of infection and explored procedure specific and patient specific risks for CRP elevation.Results: 117 patients were included. Differences in post-operative CRP measurement between procedures are statistically significant on days 1 to 3 (p <0.05). Using receiver operator characteristics, CRP performs well as a marker of infection from postoperative days (POD) 2 to 8. Discriminatory power is best for patients with septic shock, peaking at POD 5 (<0.0001). In binary logistic regression, adjusting for operation, route, and Charlson Index, CRP remained a statistically significant independent marker of infection from POD 2 to 6. Conclusion:CRP has high discriminatory power on PODs 2 to 6, particularly for septic shock. The individual major procedures and the route of access have a large influence on postoperative CRP.A larger cohort is required to accurately define normal ranges for CRP adjusted to both procedure specific and patient specific factors.