Audibert 2001.
| Clinical features and settings | Routine screening | |
| Participants | 4130 participants France ‐ single centre May 1994 to December 1997 Pregnant women Mean maternal age 30.1 years (all under 38 years) Singleton pregnancies 12‐13 weeks' gestation Crown rump length between 38 mm and 84 mm |
|
| Study design | Prospective consecutive series study | |
| Target condition and reference standard(s) | Down's syndrome: 12 cases Reference standards: prenatal karyotype conducted (in 7.6% of patients) depending on presence of risk > 1/125, high maternal age, parental anxiety, history of chromosomal defects or parental translocation or abnormal second trimester scan Cytogenetic testing of newborns with suspected abnormalities Postmortum on terminations of pregnancy or miscarriages Follow‐up to neonatal examination in newborns |
|
| Index and comparator tests | Maternal age First trimester NT planned at 12‐13 weeks, 3 mm cut‐off Second trimester serum hCG between 14 and 17 weeks (Amerlite, Orthoclinical diagnostics machine) Second trimester serum AFP between 14 and 17 weeks (Amerlite, Orthoclinical diagnostics machine) Serum tests in 3790 women Risk cut off 1:250 |
|
| Follow‐up | Outcome assessed at delivery and postnatal paediatric examination. 35 women were lost to follow‐up and excluded from the analysis. 340 women had first trimester NT but not second trimester serum testing | |
| Aim of study | To compare first trimester NT and second trimester maternal serum measurements as alternative methods of antenatal screening in a low risk population and to evaluate the consequence of combining the results in the estimation of risk | |
| Test characteristics | ||
| Reference standard used | ||
| Notes | Women lost to follow‐up were excluded in the final analysis. All detected cases resulted in termination. | |
| 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 | Yes | NT was not measured or not recorded in 219 women and these patients were excluded from the study |
| Withdrawals explained? All tests | Yes | 35 women were lost to follow‐up (they had all had normal NT results). 340 women who did not want second trimester serum screening withdrew from that part of the study |