Summary of findings 2. Xpert Ultra and Xpert MTB/RIF in pleural fluid.
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Participants: people presumed to have pleural tuberculosis Prior testing: people who received Xpert Ultra or Xpert MTB/RIF testing may first have undergone a health examination (history and physical examination) and received a chest radiograph Role: initial test, replacement for usual practice, which may include more invasive tests, such as pleural biopsy Settings: primarily tertiary care centres (the index test was often run in reference laboratories) Index tests: Xpert Ultra and Xpert MTB/RIF Reference standard: solid or liquid culture Studies: cross‐sectional studies Limitations: in most studies, participants were evaluated at a tertiary care centre, or if the clinical setting was not reported, the test was performed at a reference laboratory Xpert Ultra pooled sensitivity (95% CrI): 75.0% (58.0 to 86.4); pooled specificity (95% CrI): 87.0% (63.1 to 97.9) Xpert MTB/RIF pooled sensitivity (95% CrI): 49.5% (39.8 to 59.9); pooled specificity (95% CrI): 98.9% (97.6 to 99.7) | |||||
| Xpert Ultra result | 1000 people tested for TB using Xpert Ultra (95% CrI) | Number of participants (studies) | Certainty of the evidence (GRADE) | ||
| Prevalence of 2.5% | Prevalence of 10% | Prevalence of 20% | |||
| True‐positives (patients with pleural TB) | 19 (14 to 22) |
75 (58 to 86) |
150 (116 to 173) |
158 (4) | ⊕⊝⊝⊝ Very lowa,b,c |
| False‐negatives (patients incorrectly classified as not having pleural TB) | 6 (3 to 11) |
25 (14 to 42) |
50 (27 to 84) |
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| True‐negatives (patients without pleural TB) | 848 (615 to 955) |
783 (568 to 881) |
696 (505 to 783) |
240 (4) | ⊕⊝⊝⊝ Very lowa,d,e |
| False‐positives (patients incorrectly classified as having pleural TB) | 127 (20 to 360) |
117 (19 to 332) |
104 (17 to 295) |
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| Xpert MTB/RIF result | 1000 people tested for TB using Xpert MTB/RIF (95% CrI) | Number of participants (studies) | Certainty of the evidence (GRADE) | ||
| Prevalence of 2.5% | Prevalence of 10% | Prevalence of 20% | |||
| True‐positives (patients with pleural TB) | 12 (10 to 15) |
50 (40 to 60) |
99 (80 to 120) |
644 (25) | ⊕⊕⊝⊝ Lowf,g,h |
| False‐negatives (patients incorrectly classified as not having pleural TB) | 13 (10 to 15) |
50 (40 to 60) |
101 (80 to 120) |
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| True‐negatives (patients without pleural TB) | 964 (952 to 972) |
890 (878 to 897) |
791 (781 to 798) |
2421 (25) | ⊕⊕⊕⊕ High |
| False‐positives (patients incorrectly classified as having pleural TB) | 11 (3 to 23) |
10 (3 to 22) |
9 (2 to 19) |
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Abbreviations: CrI: credible interval; TB: tuberculosis.
We included plausible prevalence estimates for the target condition suggested by the WHO. For Xpert Ultra, the median prevalence of tuberculosis in the included studies was 46.2%. For Xpert MTB/RIF, the median prevalence of tuberculosis in the included studies was 19.8%.
aWe were interested in how Xpert Ultra performed in patients presumed to have extrapulmonary tuberculosis who were evaluated as they would be in routine practice. However, most studies did not report information on the clinical setting. We downgraded one level for indirectness. bFor individual studies, sensitivity estimates ranged from 48% to 84%. We could not explain the heterogeneity by study quality or other factors. We downgraded one level for inconsistency. cThere was a low number of participants contributing to this analysis for the observed sensitivity. As we had already downgraded for inconsistency, we downgraded one level for imprecision. dFor individual studies, specificity estimates ranged from 65% to 100%. We could not explain the heterogeneity by study quality or other factors. We downgraded one level for inconsistency. eWe thought the wide 95% CrI around false‐positives and true‐negatives would likely lead to different decisions depending on which confidence limits are assumed. As we had already downgraded for inconsistency, we downgraded one level for imprecision. fWe were interested in how Xpert MTB/RIF performed in participants presumed to have extrapulmonary tuberculosis who were evaluated as they would be in routine practice. However, most studies did not report information on the clinical setting. We downgraded one level for indirectness. gFor individual studies, sensitivity estimates ranged from 10% to 100%. We could not explain the heterogeneity by study quality or other factors. We downgraded one level for inconsistency. hAs we had already downgraded for inconsistency, we did not downgrade further for imprecision.
GRADE certainty of the evidence
High: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect.
The results presented in this table should not be interpreted in isolation from results of the individual included studies contributing to each summary test accuracy measure.