Wright 2010 North York.
| Clinical features and settings | Routine screening | |
| Participants | 239 participants: 43 cases and 196 controls (35 cases and 173 controls with second trimester testing) matched for maternal and gestational age and sample date USA ‐ The North York General Hospital dataset December 1999 ‐ November 2007 Pregnant women Singleton pregnancies 11‐13 and 14‐20 weeks' gestation |
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| Study design | Case‐control study | |
| Target condition and reference standard(s) | Down's syndrome: 43 cases Reference standards: karyotyping or follow‐up to birth |
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| Index and comparator tests | Maternal age Fresh samples tested for: First trimester PAPP‐A (PerkinElmer) Second trimester AFP, uE3, and hCG (PerkinElmer) Frozen serum samples tested for: First trimester hCG and uE3 (details not reported) Second trimester PAPP‐A (details not reported) Frozen samples tested blind to other results and pregnancy outcome |
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| Follow‐up | Details not reported | |
| Aim of study | To provide estimates and confidence intervals for the performance (detection and false positive rates) of screening for Down's syndrome using repeated measures of biochemical markers from first and second trimester maternal serum samples taken from the same woman | |
| Test characteristics | ||
| Reference standard used | ||
| 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 | No | No details given for test failures/uninterpretable measurements |
| Withdrawals explained? All tests | No | No details of withdrawals given |
AFP: alpha‐fetoprotein ß hCG: beta human chorionic gonadotrophin CVS: chorionic villus sampling ELISA: enzyme‐linked immunosorbent assay hCG: human chorionic gonadotrophin NT: nuchal translucency PAPP‐A: pregnancy‐associated plasma protein‐A SD: standard deviation uE3: unconjugated oestriol