Direct comparison of the diagnostic accuracy between blood and cerebrospinal fluid procalcitonin levels in patients with meningitis.

Objective: To compare the clinical utility of serum and cerebrospinal fluid (CSF) procalcitonin (PCT) for the diagnosis of bacterial meningitis (BM) among patients with suspected meningitis.

Methods: Patients with meningitis-like symptoms (n=120), admitted to the Second People's Hospital of Wuxi or the Changhai Hospital of Shanghai between January 2011 and December 2013, were prospectively and consecutively enrolled in this study. BM was finally diagnosed by CSF culture, Gram staining, quantitative polymerase chain reaction (qPCR), and treatment response. The diagnostic accuracy of the serum and CSF PCT was assessed by receiver operator characteristic (ROC) curve analysis. The relationship between CSF and serum PCT levels as well as the CSF leukocyte count and protein level was analyzed by Spearman's correlation analysis.

Results: PCT level in both the serum and CSF was significantly increased in the BM patients. The area under ROC curve of serum PCT for the diagnosis of BM was 0.96 (95% confidence interval (CI): 0.93-1.00), significantly higher than that of CSF PCT (0.90, 95% CI: 0.83-0.96). Using 0.88ng/mL as the threshold, the diagnostic sensitivity, specificity, and accuracy of serum PCT for the diagnosis of BM were 0.87 (95% CI, 0.73-0.95), 1.00 (95% CI, 0.95-1.00), and 95%, respectively. The serum PCT level was positively correlated with the CSF PCT level, leukocyte count, and protein level.

Conclusion: Both the serum and CSF PCT had a high diagnostic value for BM among suspected meningitis patients, and serum PCT demonstrated a superior diagnostic value compared to CSF PCT.