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. Author manuscript; available in PMC: 2020 Mar 5.
Published in final edited form as: Lancet Infect Dis. 2020 Jan 7;20(3):308–317. doi: 10.1016/S1473-3099(19)30550-X

Table 2.

Diagnostic performance of Xpert, Ultra and MGIT for the diagnosis of TBM

CSF Test N Sensitivity vs. composite microbiologic endpoint a, b P-value c Sensitivity vs. case definition d,e P-value d NPV vs. case definition e Specificity vs. case definition e
Xpert Ultra 204 92.9% (39/42) [80.5 – 98.5%] - 76.5% (39/51) [62.5 – 87.2%] - 92.7% (153/165) [87.6 – 96.2%] 100% (153/153) [97.6 – 100%]
Xpert MTB/Rif 166 65.8% (25/38) [48.6 – 80.4%] 0.006 55.6% (25/45) [44.0 – 70.4%] 0.001 85.8% (121/141) [78.9 – 91.1%] 100% (121/121) [97.0 – 100%]
MGIT Culture 142 72.2% (27/37) [55.9 – 86.2%] 0.09 61.4% (27/44) [45.5 – 75.6%] 0.02 85.2% (98/115) [77.4 – 91.1%] 100% (98/98) [96.3 – 100%]

Values are percent (numerator/denominator) and [95% Confidence Interval]

a

Composite microbiological endpoint included any positive CSF test including ZN stain microscopy, Xpert, Xpert Ultra, or MGIT culture.

b

Specificity (and positive predictive value) versus the composite endpoint is by definition 100% as the index test is included in the reference standard of ‘definite’ TBM. If the Ultra result is excluded when assigning the case definition, the specificity of Ultra is 96% (153/160, 95% CI 91-98%) and the PPV is 82% (32/39, (5% CI 66-93%).

c

McNemar’s test comparing the sensitivity of Xpert or MGIT culture to Xpert Ultra.

d

Cochran–Mantel–Haenszel test comparing the distribution of Xpert or MGIT to Xpert Ultra results versus the uniform clinical standard of definite/probable TBM or not.

e

Composite case definition for probable or definite TBM is as per the published uniform definition

PPV: positive predictive value, NPV, negative predictive value