Niemimaa 2001.
| Clinical features and settings | Routine screening | |
| Participants | 2515 participants Finland ‐ primary care centres and maternity clinics of hospitals During 1999 Pregnant women 17.5% aged ≥ 35 years 10‐13 weeks' gestation |
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| Study design | Prospective cohort | |
| Target condition and reference standard(s) | Down's syndrome: 8 cases Reference standards: invasive testing (patients considered high risk based on NT screening) or follow‐up to birth |
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| Index and comparator tests | Maternal age First trimester NT (≥ 3 mm) (64% of women) (method not described) Fresh serum tested for: First trimester free ßhCG and PAPP‐A (Wallac analytes and 1st trimester risk calculation programme maternal weight correction) Risk cut‐point 1:250 |
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| Follow‐up | Follow‐up data from maternity clinics and the National Research and Development Centre for Welfare and Health. Test negative patients followed up by contacting all maternity clinics and the National Research and Development Centre for Welfare and Health. Unclear if follow‐up information was obtained in all cases | |
| Aim of study | To evaluate efficacy of combining first trimester maternal serum and fetal NT measurement in screening for Down's syndrome in Finland | |
| 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 |