Quezada 2015.

Study characteristics
Patient sampling	Study design: prospective cohort study. Participants: self‐selected pregnant women from the general population presenting for aneuploidy screening (without prior risk of fetal aneuploidy). Inclusion criteria: pregnant women between 10 to 11 weeks’ gestation with singleton pregnancy who underwent the combined test. Exclusion criteria: multifetal pregnancies.
Patient characteristics and setting	Number enrolled: 2905 pregnant women. Number available for 2 x 2 table: 2785 pregnant women (subgroup of 96%). Setting: 1 centre. Fetal Medicine Centre in London, UK. Recruitment period: October 2012 to January 2014. Ethnicity: Caucasian (88.5%), South Asian (6.0%), East Asian (3.3%), Afro‐Caribbean (0.7%) and mixed (1.5%). Median gestational age (range): 10.6 (10 to 11.9) weeks. Median maternal age (range): 36.9 (20.4 to 51.9) years. Relevant tests carried out prior to index test: none. Language of the study: English.
Index tests	gNIPT by TMPS (DANSR assay). Median fetal fraction DNA (range): 11% (4% to 40%). Blood samples for gNIPT were collected before reference standard. Cutpoint: not reported. Usually, Harmony™ prenatal test uses FORTE algorithm; positive if FORTE risk score ≥ 1%. Commercial test: Harmony™ Prenatal test by Ariosa Diagnostics, Inc. The traditional screening tests (combined test at the first trimester) was also assessed. Cutpoint of combined test: 1 in 100 for T21.
Target condition and reference standard(s)	Target conditions: T21, T18 and T13. Reference standards: fetal karyotype of chorionic villi, amniotic fluid or products of conception, neonatal karyotype, neonatal clinical examination or medical record from birth.
Flow and timing	Blood samples were obtained prior to invasive procedure (reference standard). gNIPT was a first‐tier test. 122/2905 failed the initial TMPS testing (122 = 123 ‐ 1 sample lost in mail). 66/2851 samples without follow‐up were excluded. 110/122 required repeat testing using a second blood sample and results were obtained in 69/110 samples. 53/2905 samples failed during sequencing process (41 samples failed second sequencing and 12 unrepeated tests) (no gNIPT result).
Comparative
Aim to study	To examine, in a general population (pregnant women without prior risk of fetal aneuploidy), the performance of ccfDNA testing for T21, T18 and T13 at 10 to 11 weeks’ gestation and compare it to that of the combined test at 11 to 13 weeks' gestation.
Funding source or sponsor of the study	Study not funded by industry but Ariosa Diagnostics, Inc made sequencing and analyses.
Informations about the authors contacted	Author was contacted on: 21 April 2016 and 30 May 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 TMPS
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 2: Index Test Traditional screening tests
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?	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?	No
		High