Cerebrospinal fluid adenosine deaminase for the diagnosis of tuberculous meningitis.

Background

A consensus on the diagnostic utility of cerebrospinal fluid adenosine deaminase (ADA) for tuberculous meningitis (TBM) is lacking.

Methods

Patients aged ≥12 years admitted with CNS infections were enrolled prospectively. ADA was measured with spectrophotometry.

Results

We enrolled 251 TBM and 131 other CNS infections. The optimal cutoff of ADA was calculated at 5.5 U/l against microbiological reference standard with area under curve 0.743, sensitivity 80.7%, specificity 60.3%, positive likelihood ratio 2.03 and negative likelihood ratio 3.12. The widely used cutoff value 10 U/l had specificity 82% and sensitivity 50%. The discriminating power was higher for TBM versus viral meningoencephalitis than bacterial or cryptococcal meningitis.

Conclusion

Cerebrospinal fluid ADA has a low-to-modest diagnostic utility.