Christiansen 2010.

Clinical features and settings	Routine screening
Participants	531 participants: 28 cases and 503 controls Denmark ‐ screening programme Dates not specified Pregnant women Singleton pregnancies Median age cases 36 years (range 25‐44 years) and controls 29 years (range 17‐45 years) 8‐14 weeks' gestation
Study design	Case‐control study
Target condition and reference standard(s)	Down's syndrome: 28 cases Reference standards: karyotyping or follow‐up to birth
Index and comparator tests	Maternal age First trimester NT (details not reported) First trimester PAPP‐A and free ßhCG (details not reported) First trimester ADAM12s (AutoDELFIA/Delfia ADAM12 Research kit 4025‐0010, PerkinElmer Life and Analytical Sciences, on the 1235 AutoDELFIA automatic immunoassay system)
Follow‐up	Cross‐referencing with the Danish Cytogenetic Central Registry
Aim of study	To examine the efficiency of a second generation assay for ADAM12
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