The dubious value of cerebrospinal fluid adenosine deaminase measurement for the diagnosis of tuberculous meningitis

Table 1 Factors confounding the interpretation of literature on CSF ADA

Factors	Variables
CSF ADA cut-offs	Study from India [1]	5 U/L	Sensitivity: 89%	Specificity: 92%
	Study from India [2]	10 U/L	Sensitivity: 66.6%	Specificity: 90%
	Study from Finland [3]	20 U/L	Sensitivity: 100%	Specificity: 99%
ADA assay types	Giusti method [8, 10]	Non-Giusti method [6, 11]		In-house method [6, 12]
Total number of participants/specimens	Range: 26 – 417 [4, 5]
Age of participants	Adults only [3]	Children only [1]		Pooled data for adults and children [6]
Definition of TBM groups	Clinical as well culture evidence was used to group participants [1] Culture-positive cases sometimes was < 10 cases [3, 9]
Definition of control groups	One infective category: bacterial meningitis only [4]
	More than one infective category: viral/aseptic meningitis, bacterial meningitis, fungal meningitis [8]
	Infective and non-infective categories: bacterial meningitis, viral meningitis, hydrocephalus, epilepsy, malignancy, subarachnoid haemorrhage, senile dementia, normal CSF [6]
HIV status	HIV status is not always specified in the literature [7, 8]

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