Weinans 2000.

Clinical features and settings	High‐risk referral for invasive testing.
Participants	63 participants: 8 cases and 55 controls matched for gestational and maternal age, maternal weight, duration of storage and smoking history. The Netherlands – single hospital. October 1997 to May 1999. Pregnant women. 10‐11 weeks' gestation.
Study design	Case‐control study.
Target condition and reference standard(s)	Down's syndrome: 8 cases. Reference standard: CVS.
Index and comparator tests	Urinary hyperglycosylated hCG, (procedures previously described in Cole 1999a).
Follow‐up	100% karyotyping.
Aim of study	To investigate the value of H‐hCG measurements in very early pregnancy (prior to 12 weeks' gestation).
Notes
Table of Methodological Quality
Item	Authors' judgement	Description
Representative spectrum? All tests	Yes	Selective testing of high‐risk women as done in practice.
Acceptable reference standard? All tests	Yes	CVS.
Partial verification avoided? All tests	Yes	All women had a reference standard.
Differential verification avoided? All tests	Yes	All women had the same reference standard.
Incorporation avoided? All tests	Yes	Reference standard was independent of the index test.
Reference standard results blinded? All tests	Yes	Reference standard interpreted without 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.

AFP: alpha‐fetoprotein
 ßhCG: beta human chorionic gonadotrophin
 CVS: chorionic villus sampling
 hCG: human chorionic gonadotrophin
 ITA: invasive trophoblast antigen
 NT: nuchal translucency
 PAPP‐A: Pregnancy‐associated plasma protein A
 SD: standard deviation
 uE3: unconjugated oestriol