Sau 2001.
| Clinical features and settings | Routine screening | |
| Participants | 3185 participants UK ‐ single hospital November 1996 to November 1998 Pregnant women Mean age 28 years (SD 5) 11‐14 and 6‐20 weeks' gestation |
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| Study design | Prospective cohort | |
| Target condition and reference standard(s) | Down’s syndrome: 8 cases Reference standards: invasive testing (women with high risk on screening) or follow‐up to birth |
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| Index and comparator tests | Maternal age First trimester NT (FMF methods, transabdominal route) in 84% of women. NT risk cut‐point of 1:100 or if NT measurement > 95th centile for that particular CRL considered screen positive. Confirmatory NT test conducted in all women positive on first NT screening Second trimester AFP, ßhCG and uE3 in 49% of women. Serum risk cut‐point 1:250 |
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| Follow‐up | Follow‐up from computerised maternity records, the neonatal database and the hospital termination of pregnancy and miscarriage record books | |
| Aim of study | To present data on the performance of biochemical screening in a population with a prior low‐risk screening result | |
| 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 | Yes | In 122 (4.3%) of women, a second NT scan was needed since the first 1 failed to obtain a measurement |
| Withdrawals explained? All tests | Yes | Of 3704 women booked for hospital delivery, 3185 had at least 1 screening test and were included in the study |