C-Reactive Protein and Erythrocyte Sedimentation Rate Predict Systemic Inflammatory Response Syndrome after Percutaneous Nephrolithotomy

Objective: The aim of the study was to test the hypothesis that high levels of preoperative C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are associated with an increased risk of systemic inflammatory response syndrome (SIRS) following percutaneous nephrolithotomy (PCNL). Materials and Methods: This is a retrospective study of patients who underwent PCNL at our institution between October 2012 and October 2013 when ESR and CRP levels were part of our standard preoperative order set. The primary endpoint was development of SIRS. Receiver operating characteristic curves were used to evaluate the discriminative ability of the test. Results: Among the 107 PCNLs performed during the study period, 35 (33%) patients had evidence of SIRS during the postoperative stay. Patients who experienced SIRS had a longer operative time (99 min vs. 85 min, p = 0.016), were more likely to have been transferred to the intensive care unit (ICU) (15% vs. 0%, p = 0.002), and experienced a longer length of stay (2 days vs. 1 day, p < 0.001). On multivariable analysis controlling for operative time and positive urine culture, ESR (odds ratio [OR] 1.32, 95% confidence interval [CI]: 1.01-1.72, p = 0.04) and CRP (OR 1.59; 95% CI: 1.07-2.37, p = 0.02) were associated with development of SIRS. Among patients without a positive urine culture, an ESR >6.5 mm/hr (AUC 0.62; 95% CI: 0.52-0.78) had sensitivity, specificity, and negative predictive value (NPV) of 70.4%, 61.5%, and 80.0%, respectively, for development of SIRS. Among all patients, a CRP >0.65 mg/dL (AUC 0.63; 95% CI: 0.51-0.74) had sensitivity, specificity, and NPV of 51.4%, 69.4%, and 74.6%. Conclusions: A preoperative blood test for ESR and CRP was predictive for the development of SIRS after PCNL. This knowledge could be used to risk stratify patients and guide duration of antibiotic prophylaxis before PCNL, particularly among those without a positive urine culture.