Wojdemann 2005.
| Clinical features and settings | Referrals for screening | |
| Participants | 8622 participants Denmark ‐ 3 obstetrics departments March 1998 to June 2001 Pregnant women Mean age 29 years, 10.8% ≥ 35 years Singleton pregnancies 11 to 14 weeks' gestation |
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| Study design | Prospective cohort | |
| Target condition and reference standard(s) | Down's syndrome: 12 cases Reference standards: invasive testing (in cases of increased risk) or follow‐up to birth |
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| Index and comparator tests | Maternal age First trimester NT (FMF methods, Logic 700 MR machine) (all women) First trimester free ßhCCG (AFP/ßhCG Auto Delfia kit) and PAPP‐A (In‐house ELISA (Sandwich)) in 6,441 women (75%) Risk cut‐point 1:250 |
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| Follow‐up | Cross‐checking with all the chromosome laboratories in Denmark. Follow‐up in 96.2% of pregnancies through patients records | |
| Aim of study | To determine the performance of screening for Down's syndrome and other major chromosomal abnormalities using NT, free ßhCG and PAPP‐A in a prospective study of a non‐selected population | |
| Notes | Uptake of screening was 73% (9,941 accepted out of 13,621 offered screening) Women with miscarriages excluded from the study 3 live Down’s syndrome births |
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| 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 could not be measured in 2.5% of cases |
| Withdrawals explained? All tests | No | No details of withdrawals given |