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 32.9‐40.5 years) and controls 32.4 years (IQR 29.0‐35.9 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 (PlGF) (Solid‐phase, two‐site fluoroimmunometric research assay (4083‐0010) on 6000 DELFIA Xpress random access platform, PerkinElmer). Modelled on UK 2002 population data. |
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| Follow‐up | Karyotype and results for pregnancy outcome were 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 PlGF 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. |