Diagnostic Accuracy of Cerebrospinal Fluid Procalcitonin and Serum Procalcitonin in Adult Patients with Bacterial Meningitis: A Cross-sectional Study

Introduction: Bacterial Meningitis (BM) is a serious health problem worldwide with high mortality and permanent long-term neurological sequelae. Cerebrospinal Fluid (CSF) analysis is the cornerstone for diagnosing BM, but the lack of specificity creates a difficult clinical scenario for initiating proper treatment. Empiric antibiotic use in patients with suspected meningitis at primary care settings decreases the yield of CSF culture and alters CSF cytological and biochemical findings, making it further difficult to diagnose BM. To overcome this difficulty, there is a need for other biochemical markers with higher sensitivity and specificity. Aim: To determine the diagnostic sensitivity and specificity of Procalcitonin (PCT) in serum and CSF in patients with BM and compare its diagnostic accuracy in both sample types. Materials and Methods: A cross-sectional study was conducted in the Department of Internal Medicine at a tertiary care centre in eastern India from September 2018 to August 2020. A total of 82 adult patients with meningitis were recruited as per the protocol, and CSF analysis was done along with estimation of PCT in serum and CSF. Receiver Operating Characteristics (ROC) curve analysis of serum and CSF PCT was used to determine sensitivity and specificity with a 95% confidence interval. Results: Out of the 82 patients recruited, 30 (36.6%) had BM. CSF PCT with a cut-off value of >0.45 ng/mL had a sensitivity of 86.7% and specificity of 92.3%. The sensitivity of serum PCT with a cut- off value of >0.6 ng/ mL was 83.3%, and specificity was 86.5%. There was no statistically significant difference in sensitivity and specificity between CSF and serum PCT in patients with BM (p-value=0.7988). Conclusion: Both serum and CSF PCT were found to have high sensitivity and specificity as markers for diagnosing BM without any statistically significant difference between them.