Ehrich 2011.

Study characteristics
Patient sampling	Study design: blinded, case‐control study (1:11) from a prospective cohort. Participants: pregnant women selected from a high‐risk population. Inclusion criteria: not reported. Exclusion criteria: not reported.
Patient characteristics and setting	Number enrolled: 480 pregnant women. Number available for 2 x 2 table: 449 pregnant women (subgroup of 94%). Setting: in clinical practice and pregnancy termination centres. Recruitment period: May 2009 to unknown date. Ethnicity: not reported. Median gestational age (range): 16 (8 to 36) weeks. Mean maternal age (range): 37 (18 to 47) years. Relevant tests carried out prior to index test: ultrasonography (nuchal translucency measurement) and biochemical screening. Language of the study: English.
Index tests	gNIPT by MPSS on Illumina Genome Analyzer IIx in 4‐plex. Minimum fetal fraction DNA as estimated with the fetal quantifier assay: 3.9%. Blood samples for gNIPT were collected before reference standard. Cutpoint: positive if Z score > 2.5. Commercial test: Sequenom's test.
Target condition and reference standard(s)	Target condition: T21. Reference standard: fetal karyotype of chorionic villi (19%) or amniotic fluid (81%).
Flow and timing	Blood samples were obtained prior or after the invasive procedure (reference standard). gNIPT was a second‐tier test. 13/480 samples excluded before sequencing process (9 for plasma volume < 3.5 mL and 4 for processing errors). 20/467 samples failed the initial MPSS testing. 20/20 samples were resequenced using the same library (10 samples in 4‐plex and 10 in monoplex) and 2/20 samples obtained a gNIPT results. 18/467 samples failed quality control during sequencing process, including 7 samples for low fetal fraction DNA (no gNIPT result).
Comparative
Aim to study	To evaluate a multiplexed massively parallel shotgun sequencing assay for noninvasive trisomy 21 detection using circulating cell‐free fetal DNA.
Funding source or sponsor of the study	Study funded by Sequenom, Inc.
Informations about the authors contacted	Author was been contacted on: 5 May and 28 September 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?	No
Did the study avoid inappropriate exclusions?	Unclear
		High	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?	No
		High