Torring 2010.

Clinical features and settings	Routine screening
Participants	691 participants: 46 cases and 645 controls Denmark ‐ nationwide screening programme Dates not reported Pregnant women Singleton pregnancies Mean maternal age cases 35 years, controls 31 years 8‐11 weeks' gestation
Study design	Case‐control study
Target condition and reference standard(s)	Down's syndrome: 46 cases Reference standards: karyotyping or follow‐up to birth
Index and comparator tests	Maternal age First trimester NT (11‐13 weeks' gestation) (FMF certified sonographers) First trimester PAPP‐A and free ßhCG (fresh serum, 8‐11 weeks' gestation) (Kryptor analyser, Brahms) First trimester ADAM 12 (frozen serum, 8‐11 weeks' gestation) (Kyptor analyser, assay by Cezanne SAS, TRACE technology)
Follow‐up	Not reported
Aim of study	To determine whether ADAM 12 is a useful serum marker for fetal trisomy 21 using the mixture model
Notes
Table of Methodological Quality
Item	Authors' judgement	Description
Representative spectrum? All tests	Yes	Routine screening of typical pregnant population
Acceptable reference standard? All tests	Yes	Karyotyping or follow‐up to birth
Partial verification avoided? All tests	Yes	All women received a reference standard
Differential verification avoided? All tests	No	Choice of reference standard depended on index test results
Incorporation avoided? All tests	Yes	Reference standard was independent of the index test
Reference standard results blinded? All tests	No	Reference standard interpreted with knowledge of some index test results
Index test results blinded? All tests	Unclear	Unclear if all index tests interpreted without knowledge of reference standard results
Relevant clinical information? All tests	Yes	Information available as would be in standard clinical practice
Uninterpretable results reported? All tests	No	No details given for test failures/uninterpretable measurements
Withdrawals explained? All tests	No	No details of withdrawals given