Wallace 1995.

Clinical features and settings	Routine screening.
Participants	112 participants. UK. Dates not stated. Pregnant women. 23 cases (maternal age 22‐44 years, mean 32 years). 89 controls matched for gestational age and duration of sample storage (maternal age 19‐38 years, mean 28 years). 11‐13 weeks' gestation.
Study design	Case‐control study.
Target condition and reference standard(s)	Down’s syndrome: 23 cases. Reference standard: not reported.
Index and comparator tests	Frozen serum tested for dimeric first trimester Inhibin A (enzyme‐linked two‐site immunoassay).
Follow‐up	Methods of follow‐up not reported.
Aim of study	To evaluate dimeric first trimester inhibin A as a possible first trimester screening marker for Down’s syndrome screening.
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	Unclear	Unclear reference standard.
Partial verification avoided? All tests	Unclear	Unclear if all women received a reference standard.
Differential verification avoided? All tests	Unclear	Unclear if the reference standard differed between women.
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	Unclear	Unclear if 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.