Remarks

• This recommendation prioritizes concurrent testing of two different sample types over theuse of a single molecular test for diagnosis of TB in children.
• Use of LC-aNAATs on isolated specimens was also evaluated. The findings supported theuse of LC-aNAATs for initial diagnostic testing for TB in children with signs or symptoms orwho screen positive for pulmonary TB, using respiratory sample, gastric aspirate, stool ornasopharyngeal aspirate, rather than smear or culture.
• This recommendation is strong despite the low certainty of evidence because the findingsindicate large desirable effects (i.e. rapid and accurate diagnosis of TB in a highly vulnerablepopulation – children – in whom diagnosing TB is often challenging) over trivial undesirableeffects (i.e. negative consequences of this testing strategy) (for more details, see GRADEevidence to decision [EtD] table, Web Annex A.4).
• The product for which eligible data met the LC-aNAAT class-based performance criteriafor this recommendation was Xpert MTB/RIF Ultra. The performance of Truenat MTB Plusand MTB-RIF Dx for this recommendation could not be assessed, as data were unavailable.

Implementation considerations

• Concurrent testing maximizes diagnostic opportunity and accuracy of case detection, is a more efficient way to address the needs of this population and is preferred even if the testing workload may increase.
• A positive result on either test is sufficient to confirm TB diagnosis.
• Patient loss to follow-up for the second test result should be monitored and prevented. Patients should be provided with information to understand the concurrent testing approach and the need for follow-up.
• Testing capacity should be secured for the second test, as volumes will increase.
• Adequate staffing capacity and training are needed to improve the collection of different sample types and laboratory processing of collected samples.
• Performing the same test on a new sample may need additional regulatory approval on a national and international level.
• Infrastructure and training on how to collect a stool sample privately should be available.
• As with all WHO-recommended TB diagnostics, quality assurance programmes for both sample types are required.
• At a primary health care level, in a situation of sputum paucity or absence, stool and nasopharyngeal aspirate may be feasible, whereas collection of more invasive specimen types (i.e. induced sputum, BAL and gastric aspirate) would require upward referral, depending local capacity and expertise. In these circumstances, performing stool testing at primary health care level and waiting for a test result before upward referral of the child may be appropriate.