Diagnostic accuracy of cerebrospinal fluid adenosine deaminase in detecting Tuberculous Meningitis

Objective: To determine diagnostic accuracy of Cerebro Spinal Fluid (CSF) Adenosine DeAminase (ADA) in detecting Tuberculous Meningitis (TBM) keeping CSF Polymerase Chain Reaction (PCR) for Mycobacterium Deoxy Ribonucleic Acid (DNA) as gold standard. Methods: This cross sectional validation study was conducted at Department of General Medicine of PNS Shifa Naval Hospital Karachi, Pakistan from Oct 2015 to Mar 2017 for a total duration of one and a half year. One hundred and thirty six patients were included. The diagnosis of TBM was based clinically on symptoms like fever, headache, altered mental state and signs of meningeal irritation with CSF findings of increased proteins, low glucose and lymphocytic pleocytosis. Lumbar puncture was done and approximately 4ml of CSF sample was withdrawn for analysis. Diagnosis of TBM was confirmed by doing CSF PCR test for mycobacterium tuberculosis DNA. Results: Total 136 patients were enrolled in this study. Mean age in our study was 47.09 +/- 12.80 years, whereas frequency and percentages of male and female patients was 102 (75%) and 34 (25%) respectively. The diagnostic accuracy, sensitivity, specificity, positive predictive value and negative predictive value of CSF ADA level in detecting TBM was 71.32%, 84.21%, 95.45%, 98.97% and 53.85% respectively. Conclusion: The study concludes that diagnostic accuracy of CSF ADA in detecting TBM is high which is proposed as an investigation to differentiate it from other causes of meningitis in places where PCR test is not available.