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. 2017 Mar 15;2017(3):CD012600. doi: 10.1002/14651858.CD012600

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
Study design Prospective cohort study
Target condition and reference standard(s) Down's syndrome: 51 cases
Reference standards: karyotyping or follow‐up to birth
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
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