Ceffa 2016.

Study characteristics
Patient Sampling	To compare viral load results, samples of children ≤ 14 years and adults ≥ 15 years of age who had been taking ART for at least 12 months, and had a viral load test ordered following the clinical flowchart normally in use (viral load test after 12 months of ART treatment), were tested. Participants were enrolled sequentially at the selected sites until the desired sample size was reached. Target enrolment was 200 exposed newborns and 300 adults and/or children, 60 samples with undetectable viral load (< 1.6 log(10) copies/mL), and 60 samples for each range group, as follows: 1.6 to 2.99 log(10) copies/mL), 3 to 3.69 log(10) copies/mL), 3.7 to 3.99 log(10) copies/mL) and > 4 log(10) copies/mL).
Patient characteristics and setting	Children and adults on ART for at least 12 months; the DREAM laboratory in Blantyre, Malawi, where samples collected at various health centres in different districts were centralized for the analyses.
Index tests	The Xpert HIV‐1 Viral Load (Cepheid, Sunnyvale, CA, USA) done in central laboratory on frozen plasma samples.
Target condition and reference standard(s)	High viral load at > 1000 copies/mL and > 40 copies/mL. Abbott RealTime HIV‐1 assay (m2000rt; Abbott Molecular Diagnostics, Mississauga, ON, Canada).
Flow and timing	EDTA blood samples were collected, and 2 aliquots of plasma from each sample were prepared and stored at −80 °C for a minimum of 1 day and a maximum of 3 months. 1 aliquot was used for routine determination with the Abbott m2000 system, and the second was processed with GeneXpert. The patients received the results of both tests in maximum of 1 month.
Comparative
Notes
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Yes
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	Unclear
Could the selection of patients have introduced bias?		Unclear risk
Are there concerns that the included patients and setting do not match the review question?			Low concern
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Unclear risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			High
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
Could the reference standard, its conduct, or its interpretation have introduced bias?		Unclear risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	No
Could the patient flow have introduced bias?		Unclear risk