Cowans 2010.
| Clinical features and settings | Routine screening | |
| Participants | 445 participants: 70 cases and 375 controls matched for storage time and gestational age January 2007 ‐ October 2008 UK Pregnant women Singleton pregnancies Mean maternal age cases 37.0 years (IQR 32.9 to 40.5 years) and controls 32.4 years (IQR 29.0 to 35.9 years) 11‐13 weeks' gestation |
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| Study design | Case‐control study | |
| Target condition and reference standard(s) | Down's syndrome: 70 cases Reference standards: karyotyping or follow‐up to birth |
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| Index and comparator tests | Maternal age First trimester NT (FMF certified sonographers) Fresh serum samples tested for: First trimester PAPP‐A and free ßhCG (Kryptor analyser, Brahms) Frozen serum samples tested for: First trimester placental growth factor (Solid‐phase, 2‐site fluoroimmunometric research assay (4083‐0010) on 6000 DELFIA Xpress random access platform, PerkinElmer) |
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| Follow‐up | Karyotype and results for pregnancy outcome received from cytogenetics laboratories and maternity units where deliveries took place | |
| Aim of study | To examine placental growth factor levels in first trimester maternal serum in trisomy 21 pregnancies and to investigate the potential value of PIGF in a first trimester screening test | |
| 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 some 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 |