Aims Tuberculous meningitis (TBM) is a severe infection which may lead to serious complication and mortality. Prompt diagnosis and treatment are essential. There is a need for a simple and fast laboratory test to differentiate TBM from other causes.
Methods Retrospective review was conducted for cerebrospinal fluid adenosine deaminase (CSF-ADA) activity which was measured at the Chemical Pathology Laboratory of Princess Margaret Hospital, the sole centre providing such service in Hong Kong, for 51 patients with suspected meningitis from nine local hospitals between June 2014 and July 2017. TBM diagnosis was defined by positive culture and/or nucleic acid amplification test result of Mycobacterium tuberculosis complex in CSF.
Results CSF-ADA activity was significantly higher in the TBM group (8.6±2.1 IU/L, n=8) than that of the non-TBM group (2.8±5.9 IU/L, n=43). The optimal clinical cut-off of 5.1 U/L for TBM diagnosis in our laboratory yielded 100% sensitivity, 91% specificity, positive likelihood ratio of 10.8 and negative likelihood ratio of 0. In rare circumstance, false elevation may be seen in non-tuberculous cause, such as central nervous system lymphoma and fungal infection.
Conclusions We recommend the use of CSF-ADA activity, which is a simple, fast and robust test for early differentiation of TBM from other causes, to facilitate timely initiation of antituberculous treatment and potentially improve patients’ outcome.
- mycobacterial infection
- adenosine deaminase
- chemical pathology
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Handling editor Tahir S Pillay.
Contributors All authors contributed to the concept or design, drafting of the manuscript and critical revision for important intellectual content. All authors had full access to the data, contributed to the study, approved the final version for publication and take responsibility for its accuracy and integrity.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Disclaimer This manuscript, or part of it, has neither been published nor is currently under consideration by any other journal.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The study was approved by the Kowloon West Cluster Research Ethics Committee of Hospital Authority, Hong Kong (KWC-REC Reference: KW/EX-19-004(130-04).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article.
Author note This manuscript, or part of it, has neither been published nor is currently under consideration by any other journal.
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