CSF-ADA as diagnostic tool for tuberculous meningitis patients.

ABSTRACT

Introduction: TB is widely prevalent in India and a common form of TB is Tuberculous Meningitis (TBM), with great mortality, mainly in childhood. Available methods of TBM diagnosis are time-consuming and expensive. ADA is being recognized as marker of T-cell-mediated immunity. There is a need for cost-effective and relatively rapid method at tertiary-healthcare-settings. The study was carried out to assess the role of CSF-ADA for TBM diagnosis. Materials and Methods: In this cross-sectional study at SSG Hospital, Baroda between June-October 2011, 50 patients and 20 controls were selected. ADA in CSF and other biochemical markers were assessed after due informed consent. Microxpress ADA-MTB reagent was used for CSF-ADA estimation. Results: Out of 50, 22 children were male and 28 were female. 17 TBM (34%), 19 PM (38%) and 14 AM (28%) cases were detected. 72% of cases had CSF-ADA levels less than 10 IIU/L (mean 4.37±1.32), CSF-ADA levels were less than 10 in all controls (mean 2.8±0.8). Comparative CSF-ADA estimation in TBM, PM and AM showed higher values for TBM (p<0.001). Sensitivity and specificity of CSF-ADS for TBM diagnosis were 78% and 98% respectively at cut-off value of 11 IU/L. Discussion: Difference in the CSF - ADA levels of meningitis due to tuberculous and non-tuberculous etiology is statistically highly significant. CSF-ADA level at 11 IU/L differentiate tuberculous from non-tuberculous meningitis with reasonable sensitivity and great specificity. A country with extremely high TB prevalence requires a robust healthcare delivery and accurate therapy to prevent subsequent emergence of MDR and XDR-TB forms. High specificity of CSF-ADA test can prove immensely useful. ADA estimation in CSF is simple, inexpensive, rapid and fairly specific method for making a diagnosis of tuberculous etiology in TBM.