Considerable Value of Cerebrospinal Fluid Adenosine Deaminase Activity in Early Diagnosis for Tuberculous Meningitis Patients in Ratchaburi Hospital

Abstract

Tuberculous meningitis (TBM) causes high mortality and serious complications due to

delayed early diagnosis. This study evaluated a diagnostic value of adenosine deaminase activity (ADA)  in cerebrospinal fluid (CSF) as a rapid screening test for TBM. Totally 121 patients with suspected symptoms of meningitis were included with 55 cases of TBM and 66 cases of non-TBM. With good performance verification of Diazyme enzymatic method used, ADA activity at a cut off value of 4.35 U/L was able to differentiate TBM from non-TBM by exhibiting a sensitivity of 89.1%, specificity  of 80.3%, positive predictive value (PPV) of 79.0% and negative predictive value (NPV) of 89.8%. The mean ADA value was significantly higher (p-value < 0.05) in TBM patients (9.65  ± 8.37 U/L; mean ± SD) than in non-TBM patients (4.08  ± 8.13 U/L; mean

± SD). The combination of ADA test and CSF examination increased the sensitivity to 96.3% and had a specificity of 63.6%. In conclusion,  determination of cerebrospinal fluid, ADA can be useful for rapid screening in early diagnosis of TBM because the assay is simple, inexpensive and reliable.