Rozenberg 2007.
| Clinical features and settings | Routine screening | |
| Participants | 14,934 participants Canada ‐ multicentre study Pregnant women Singleton pregnancies Mean maternal age 30.9 (SD 4.5) years 11‐13 weeks' gestation |
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| Study design | Prospective cohort study | |
| Target condition and reference standard(s) | Down's syndrome: 51 cases Reference standards: karyotyping or follow‐up to birth |
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| Index and comparator tests | Maternal age First trimester NT (trained assessors following protocol) First trimester PAPP‐A and free ßhCG (PerkinElmer Life Sciences) Second trimester ultrasound and/or serum markers (free ßhCG and AFP or total hCG, AFP and uE3) performed in some cases Risk cut‐point 1:250 |
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| Follow‐up | Notebooks in maternity hospitals used to record information on patient characteristics, screening and outcome at birth. Data obtained from cytogenetic laboratories and DASDY database (contains results of birth examinations). Letters sent to women with missing outcome information and, after 3 months, if there was no response, they were contacted by telephone | |
| Aim of study | To evaluate the performance, acceptability and cost‐effectiveness ratio of a pragmatic approach to screening for Down's syndrome based on the combined first trimester test supplemented by routine ultrasound at 20‐22 weeks in the general population | |
| 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 | Yes | 554 women (3.7%) did not undergo screening |