Liu 2012.

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: women who planned an invasive testing for 1 or more of the following reasons: abnormality in plasma test, older than 35 years old, infant deformity (ultrasound), taken drugs (teratogen) during early pregnancy or history of malformation caused by virus infection, history of birth defect caused by abnormal chromosome, history of fetus stopping growth or repeated spontaneous abortion or dead fetus or dead birth for unknown reason, history of chromosome abnormality in family or either of the couple, too much or little amniotic fluid. Exclusion criteria: not reported.
Patient characteristics and setting	Number enrolled: 153 pregnant women. Number available for 2 x 2 table: 153 pregnant women (whole cohort included in analyses). Setting: Henan Province People Hospital Medical. Recruitment period: October to November 2011. Ethnicity: Asian. Gestational age: more than 14 weeks. Mean maternal age (± SD; range): 32.3 (± 1.2; 20 to 44) years. Relevant tests carried out prior to index test: ultrasonography (nuchal translucency measurement) or biochemical screening or both. Language of the study: Chinese.
Index tests	gNIPT by MPSS on Illumina HiSeq sequencer in multiplex. Fetal fraction DNA: not reported. Blood samples for gNIPT were collected 30 minutes before reference standard. Cutpoint: positive if Z score ≥ 3. It is not reported if gNIPT was a commercial or an in‐house test.
Target condition and reference standard(s)	Target conditions: T21, T18, T13, 45,X and 47,XYY. 47,XXY and 47,XXX were also assess but no case were found. Reference standard: fetal karyotype of amniotic fluid.
Flow and timing	Blood samples for gNIPT were obtained 30 minutes 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 determine the feasibility and accuracy of detecting numerical chromosomal abnormalities by high‐flux sequencing analysis of ccfDNA from maternal plasma.
Funding source or sponsor of the study	Study funded by by the Nalional Natural Science Foundation of China and a Medical Science and Technology Research Project of Henan Province.
Informations about the authors contacted	Author was contacted on 11 April 2016 but contact author's email is no longer valid.
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?	Unclear
		Unclear	Low
DOMAIN 2: Index Test MPSS
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
		Low	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?	Yes
		Low	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