Xpert MTB/RIF assay for diagnosis of extrapulmonary tuberculosis in children: a systematic review and meta-analysis.

Background: The Xpert® MTB/RIF assay (Xpert; Cepheid, Sunnyvale, CA, USA) is a cartridge-based nucleic acid amplification assay for rapidly diagnosing tuberculosis and assessing antibiotic sensitivity. Although previous evidence supports the use of Xpert for diagnosing extrapulmonary tuberculosis (EPTB) in adults, information regarding the accuracy of Xpert for EPTB only in children is lacking. This meta-analysis was performed to assess the accuracy of Xpert for detecting EPTB in children.

Methods: We searched the MEDLINE, EMBASE, and Cochrane Infectious Diseases Group Specialized Register from January 1, 2010 to July 16, 2019 for studies of the diagnostic performance wherein Xpert was analyzed against cultures or composite reference standards for < 18-year-old children with EPTB.

Results: In only pediatric studies, 8 studies including 652 samples were selected. The pooled sensitivity and specificity of Xpert for all samples were 71% (95% CI 0.63-0.79) and 97% (95% CI 0.95-0.99), respectively. The area under the summary receiver operating characteristic (sROC) curve was 0.89. For lymph node tissues or aspirates, the pooled sensitivity and specificity of Xpert were 80% (95% CI 0.70-0.88) and 94% (95% CI 0.89-0.97), respectively; for cerebrospinal fluid (CSF), these values were 42% (95% CI 0.22-0.63) and 99% (95% CI 0.95-1.00), respectively.

Conclusion: Overall, Xpert displayed high specificity but modest sensitivity across various samples for diagnosing pediatric EPTB compared to the composite reference standard. Xpert sensitivity varied with the sampling site and was especially lower in CSF samples. Positive Xpert results may be considered to indicate a presumptive case of pediatric EPTB, whereas negative test results indicate that the possibility of pediatric EPTB should not be excluded.