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Xpert assay offers better sensitivity for diagnosis of pediatric TB

Xpert assay provided better sensitivity for the diagnosis of pulmonary tuberculosis in children when compared with microscopy, and its scale-up will improve access to tuberculosis diagnostics for children, according to study results.

“Our results show that Xpert [Xpert MTB/RIF, Cepheid] assay can diagnose tuberculosis equally well in different respiratory specimens and is better than smear microscopy, but that overall sensitivity remains suboptimum with culture,” Anne K. Detjen, MD, of the International Union Against Tuberculosis and Lung Disease in New York, and colleagues wrote.

The researchers searched Medline and Scopus for studies without language or date restrictions to estimate the sensitivity and specificity of the Xpert test compared with smear microscopy in the diagnosis of pulmonary tuberculosis in children. They identified 15 studies, including 4,768 respiratory specimens in 3,640 children investigated for TB. Culture tests were positive for TB in 12% of all children evaluated, while Xpert testing was positive in 11% of cases.

Compared with culture, the pooled sensitivities (62%; 95% CI, 51%-73%) and specificities (98%; 95% CI, 97%-99%) of Xpert for tuberculosis detection were high when utilized with expectorated or induced sputum samples. Sensitivity using Xpert was 36% greater than smear microscopy in those cases and 44% greater using gastric lavage samples.

“The ongoing rollout of Xpert in low-income and middle-income settings should increase access to much needed diagnostics for tuberculosis and rifampicin resistance in children,” the researchers wrote. “The effect of Xpert can be optimized if its implementation is complemented by efforts to strengthen health systems including improved specimen collection, linkage of specimens to diagnostics, and timely reporting of results.”

Disclosure: The researchers report no relevant financial disclosures.