Montalvo 2005.

Clinical features and settings	Routine screening
Participants	4538 participants who had follow‐up data available Spain ‐ tertiary hospital July 1999 ‐ October 2004 Pregnant women Mean age 31.1 years (14‐49 years), 25.9% of patients ≥ 35 years Singleton pregnancies 10‐14 weeks' gestation
Study design	Prospective cohort
Target condition and reference standard(s)	Down's syndrome: 19 cases Reference standards: invasive testing offered to women considered high risk from screening results or follow‐up to birth
Index and comparator tests	Maternal age First trimester NT (Methods described by Nicholaides) First trimester PAPP‐A and free ßhCG (Kryptor Trace system, CIS Bio International) Risk cut‐point 1:270
Follow‐up	Only patients with postnatal results available are included in the study
Aim of study	To report the experience of using of use of the combined first trimester screening test
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 index test results
Index test results blinded? All tests	Yes	Index test 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