Lam 2002.
| Clinical features and settings | Routine screening | |
| Participants | 16,237 participants Hong Kong ‐ multicentre study 1997 to 2000 Pregnant women Mean age 30.5 years (19% ≥ 35 years) (unaffected pregnancies) 10‐14 weeks and 15‐18 weeks' gestation |
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| Study design | Prospective cohort | |
| Target condition and reference standard(s) | Down's syndrome: 35 cases Reference standards: women considered high risk offered CVS (0.7%) or amniocentesis (11.8%). Follow‐up to birth |
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| Index and comparator tests | Maternal age First trimester NT (FMF methods) Second trimester free ßhCG and AFP (methods not stated) (All women underwent both NT and biochemical testing) |
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| Follow‐up | By review of hospital and laboratory records and by directly telephoning women. Participants who defaulted the second trimester serum tests (n = 1015) and those who miscarried after NT but before serum testing (n = 91) were excluded from the study. Outcome obtained in only 15,253 patients (93.9%) |
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| Aim of study | To report data on participants undergoing both first and second trimester methods of screening to assess the relative efficacy of different methods of screening | |
| 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 | No | Not all women received a reference standard (6.1% had no ascertainment of pregnancy outcome) |
| 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 | Yes | NT successful in 99.8% of cases |
| Withdrawals explained? All tests | No | No details of withdrawals given |