Babbur 2005.
| Clinical features and settings | Women requesting screening (self‐paying service) and women attending on account of previous pregnancy history of fetal abnormality | |
| Participants | 3188 participants Cambridge, UK ‐ Maternity Hospital August 2001‐March 2004 Singleton pregnancies Pregnant women Median age 37 years (19‐46 years) 11‐14 weeks' gestation 45‐84 mm crown‐rump length Viable fetus |
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| Study design | Prospective cohort study | |
| Target condition and reference standard(s) | Down's syndrome: 25 cases Reference standards: invasive testing offered to women with NT > 3 mm or risk > 1:250 as defined by combined NT and serum results (chorionic villus sampling from 11 weeks, amniocentesis from 15 weeks). Rapid in situ hybridisation test in patients with risk > 1:30. No details given of any follow‐up to birth |
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| Index and comparator tests | First trimester NT in all women (FMF methods) Second trimester serum biochemistry (AutoDELFIA(TM) time‐resolved fluorimmunoassay (Perkin Elmer)) at 14 weeks. Offered to patients with negative first trimester NT (2725 accepted, 85%) |
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| Follow‐up | Details of follow‐up to birth not given | |
| Aim of study | To determine the detection and false positive rates for trisomy 21 using 2‐stage combined nuchal translucency and triple testing whilst disclosing abnormal NT measurements at the scan | |
| Notes | Women with miscarriages excluded | |
| 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 | No | No details given for test failures/uninterpretable measurements |
| Withdrawals explained? All tests | Yes | 463 patients having NT did not go on to have serum testing |