Ability of procalcitonin to predict bacterial meningitis in the emergency department.

INTRODUCTION: The aim of this study was to analyse and compare procalcitonin (PCT) and C-reactive protein (CRP) as tools for detecting bacterial meningitis and predicting bacteraemia. METHODS: Prospective, observational, and descriptive analytical study of 98 consecutive patients aged ≥15 years and diagnosed with acute meningitis in an emergency department between August 2009 and July 2013. RESULTS: We analysed 98 patients with AM (66 males [67%]); mean age was 44±21 years. The diagnosis was bacterial meningitis in 38 patients (20 with bacteraemia); viral meningitis in 33; probable viral meningitis in 15; and presumptively diagnosed partially treated acute meningitis in 12. PCT had the highest area under the ROC curve (AUC) (0.996; 95% CI, 0.987-1; p<0.001). With a cutoff of ≥ 0.74 ng/ml, PCT achieved 94.7% sensitivity, 100% specificity, negative predictive value (NPV) of 93.9%, and positive predictive value (PPV) of 100%. The mean levels for PCT were11.47±7.76 ng/ml in bacterial meningitis vs. 0.10±0.15 ng/ml in viral meningitis (p <0.001). The AUC for CRP was 0.916 and a cutoff of ≥ 90 mg/L achieved 67.5% sensitivity, 86.3% specificity, PPV of 89.2%, and NPV of 90.4%. As a predictor of bacteraemia in bacterial meningitis, only PCT delivered a significant difference (14.7±7.1 ng/mL vs. 4.68±3.54 ng/mL, p<0.001). A cutoff of ≥ 1.1 ng/mL achieved 94.6% sensitivity, 72.4% specificity, NPV of 95.4%, and PPV of 69.2%; the AUC was 0.965 (95% CI, 0.921-1; p<0.001). CONCLUSIONS: PCT has a high diagnostic power for acute meningitis in emergency department patients. PCT outperforms CRP in the detection of bacterial aetiology and is a good predictor of bacteraemia in bacterial meningitis.