Summary of findings 3. Xpert Ultra and Xpert MTB/RIF in lymph node aspirate.
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Participants: people presumed to have lymph node tuberculosis Prior testing: people who received Xpert testing may first have undergone a health examination (history and physical examination) and possibly received a chest radiograph Role: initial test, replacement for usual practice, which may include more invasive tests, such as biopsy of affected organs Settings: primarily tertiary care centres (the index test was often run in reference laboratories) Index tests: Xpert Ultra and Xpert MTB/RIF Reference standard: composite reference standard 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 performed at a reference laboratory Xpert Ultra sensitivity (95% CI): 70% (51 to 85); specificity: 100% (92 to 100) Xpert MTB/RIF pooled sensitivity (95% CrI): 81.6% (61.9 to 93.3); pooled specificity: 96.4% (91.3 to 98.6) | |||||
| Xpert Ultra result | 1000 people tested for TB using Xpert Ultra (95% Cl) | Number of participants (studies) | Certainty of the evidence (GRADE) | ||
| Prevalence of 2.5% | Prevalence of 10% | Prevalence of 20% | |||
| True‐positives (patients with lymph node TB) | 17 (13 to 21) | 70 (51 to 85) | 140 (102 to 170) | 30 (1) | ⊕⊝⊝⊝ Very lowa,b |
| False‐negatives (patients incorrectly classified as not having lymph node TB) | 8 (4 to 12) | 30 (15 to 49) | 60 (30 to 98) | ||
| True‐negatives (patients without lymph node TB) | 975 (897 to 975) | 900 (828 to 900) | 800 (736 to 800) | 43 (1) | ⊕⊝⊝⊝ Very lowa,c |
| False‐positives (patients incorrectly classified as having lymph node TB) | 0 (0 to 78) | 0 (0 to 72) | 0 (0 to 64) | ||
| Xpert MTB/RIF result | 1000 people tested for TB using Xpert MTB/RIF (95% Crl) | Number of participants (studies) | Certainty of the evidence (GRADE) | ||
| Prevalence of 2.5% | Prevalence of 10% | Prevalence of 20% | |||
| True‐positives (patients with lymph node TB) | 20 (16 to 23) | 81 (62 to 92) | 162 (124 to 184) | 377 (4) | ⊕⊕⊝⊝ Lowd,e |
| False‐negatives (patients incorrectly classified as not having lymph node TB) | 5 (2 to 9) | 19 (8 to 38) | 38 (16 to 76) | ||
| True‐negatives (patients without lymph node TB) | 935 (878 to 958) | 863 (811 to 885) | 767 (721 to 786) | 302 (4) | ⊕⊕⊝⊝ Lowd,e |
| False‐positives (patients incorrectly classified as having lymph node TB) | 40 (17 to 97) | 37 (15 to 89) | 33 (14 to 79) | ||
Abbreviations: Crl: credible interval; TB: tuberculosis.
We included plausible prevalence estimates for the target condition suggested by the WHO. For Xpert Ultra, the prevalence of tuberculosis in the included study was 41%. For Xpert MTB/RIF, the median prevalence of tuberculosis in the included studies was 55.5%.
aWe identified only one study, which was conducted at a tertiary referral centre in South Africa, a high TB burden country. Most participants (84%) were seen as outpatients. With only one study, applicability to other settings comes with some uncertainty. We downgraded one level for indirectness. bThere were very few participants contributing to this analysis. The 95% CI was very wide. We downgraded two levels for imprecision. cThere were very few participants contributing to this analysis. The 95% CI was wide. We downgraded two levels for imprecision. dThe composite reference standard was defined by the primary study authors and therefore, was not uniform. We downgraded one level for risk of bias. eFor indirectness, regarding applicability, for the patient population, we considered most studies to have unclear concern. We were interested in how Xpert MTB/RIF performed in patients presumed to have extrapulmonary TB who were evaluated as they would be in routine practice. However, none of the studies reported this information. We downgraded one level for indirectness.
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.