Stenhouse 2004.
| Clinical features and settings | Routine screening | |
| Participants | 5000 participants UK ‐ maternity clinic Over a 3 year period ‐ dates not specified Pregnant women Singleton pregnancies Median age 32 years (14‐45 years), 27% ≥ 35 years 11 to 14 weeks' gestation |
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| Study design | Prospective cohort | |
| Target condition and reference standard(s) | Down's syndrome: 15 cases Reference standards: invasive testing offered to women with screening risk of > 1:250 or follow‐up to birth |
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| Index and comparator tests | Maternal age First trimester NT (FMF methods, ATL HDI 3500, ATL HDI 3000, Toshiba SSA‐340A and Kretz Voluson) First trimester free ßhCG and PAPP‐A (Clotted venous blood samples, AutoDELFIA immunoassy, Perkin Elmer) |
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| Follow‐up | Details not reported | |
| Aim of study | To assess the effectiveness of combined ultrasound and biochemical screening for chromosomal abnormalities in singleton pregnancies in a routine antenatal clinic and laboratory setting | |
| Notes | Fetal loss rate for invasive testing was 1.4% (3/212) | |
| 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 | Unclear | Unclear if 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 | Yes | NT not successfully measured in 25 patients (0.5%) |
| Withdrawals explained? All tests | No | No details of withdrawals given |