Okun 2008 FTS.
| Clinical features and settings | Routine screening | |
| Participants | 14,487 participants undergoing first trimester screening (a separate cohort of 30,792 pregnancies were evaluated for integrated screening) November 2002 ‐ December 2005 Canada ‐ 2 hospitals Pregnant women Singleton pregnancies Mean maternal age 34 years 11‐14 weeks' gestation |
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| Study design | Prospective cohort | |
| Target condition and reference standard(s) | Down's syndrome: 62 cases Reference standards: karyotyping or follow‐up to birth |
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| Index and comparator tests | Maternal age First trimester NT (most sonographers had FMF certification) First trimester free ßhCG and PAPP‐A (DSX Four Plate Automated ELISA Processing system, Dynex Technologies and DPC Immulite 2000 automated immunoassay analyser, Siemens Medical Solutions Diagnostics) Risk cut‐point 1:200 or NT ≥ 3.5 mm Results presented with and without adjustment for bias due to miscarriages (viability bias) |
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| Follow‐up | From cytogenetics databases in both Hospitals, the Canadian Institute for Health Information, labour and delivery databases, written and phone follow‐up with care providers and phone follow‐up with women after birth | |
| Aim of study | To evaluate the performance of integrated prenatal screening and first trimester combined screening for trisomy 21 in a large Canadian urban centre | |
| 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 | 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 | No | No details of withdrawals given |