Spencer 1999.
| Clinical features and settings | Women referred for invasive testing or self‐referred for screening | |
| Participants | 1156 participants: 210 cases and 946 controls matched for gestational and maternal age UK ‐ fetal medicine research centre Dates not specified Pregnant women Median maternal age 38 years (19‐46 years) (cases) and 36 years (15‐47 years) (controls) 10‐14 weeks' gestation |
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| Study design | Case‐control study | |
| Target condition and reference standard(s) | Down's syndrome: 210 cases Reference standards: invasive testing (high‐risk women) or follow‐up to birth |
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| Index and comparator tests | Maternal age First trimester NT (methods not reported) Frozen serum samples tested for: First trimester free ßhCG and PAPP‐A (Kryptor analyser, time resolved amplified cryptate emission (TRACE)) |
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| Follow‐up | Stated that pregnancy outcome was ascertained in all women | |
| Aim of study | To examine the potential impact of combining maternal age with fetal NT thickness and maternal serum free ßhCG and PAPP‐A in screening for trisomy 21 at 10‐14 weeks of gestation | |
| Notes | ||
| Table of Methodological Quality | ||
| Item | Authors' judgement | Description |
| Representative spectrum? All tests | Yes | Selective testing of high‐risk women as done in practice |
| 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 | Unclear | Unclear if all index tests 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 |