Sukhikh 2015.

Study characteristics
Patient sampling	Study design: prospective cohort study. Participants: pregnant women selected at high risk of fetal aneuploidy presenting for invasive testing. Inclusion criteria: not reported. Exclusion criteria: not reported.
Patient characteristics and setting	Number enrolled: 200 pregnant women. Number available for 2 x 2 table: 200 pregnant women (whole cohort included in analyses). Setting: not reported. Recruitment period: not reported. Ethnicity: not reported. Median gestational age (range): 14 (10 to 20) weeks. Maternal age: not reported. Relevant tests carried out prior to index test: ultrasonography (nuchal translucency measurement) or biochemical screening or both. Language of the study: Russian.
Index tests	gNIPT by MPSS on Ion Proton™ sequencer. Fetal fraction DNA: not reported. Blood samples for gNIPT were collected before reference standard. Cutpoint: 1) Positive for T21 and T18 if T score > 5. 2) Positive for T13 if T score > 4. 3) Positive for 45,X if T score for chrom. X > 0.04 and for chrom. Y < 0.04. In‐house test.
Target condition and reference standard(s)	Target conditions: T21, T18, T13 and 45,X. Reference standard: fetal karyotype of chorionic villi, amniotic fluid or placenta.
Flow and timing	Blood samples for gNIPT were obtained prior to the invasive procedure (reference standard). gNIPT was a second‐tier test. No failed sample reported. No repeated test reported.
Comparative
Aim to study	To estimate the feasibility of using a next‐generation sequencing technique for the noninvasive prenatal diagnosis of fetal aneuploidies.
Funding source or sponsor of the study	Funding source not reported.
Informations about the authors contacted	Author was contacted on: 9 September and 4 October 2016. No reply received from the author.
Notes
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	No
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	No
		High	Low
DOMAIN 2: Index Test MPSS
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
		Unclear	Low
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
		Unclear	Low
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Yes
Did all analysed patients receive the reference standard?	Yes
Were all patients included in the analysis?	Yes
		Low