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KCE reports vol. 6A Prenatale zorg 207
4. Screening for DownÊs syndrome
What is the incidence of DownÊs syndrome and what is the odds at different maternal age-levels?
Study Ref Population Intervention Outcomes Results Comments Study
ONS,
2000
Morris et
al., 2002
4
[303]
4
[311]
All children in
England and Wales
All antenatal or
postnatally
diagnosed and
confirmed cases (via
a karyotype) of
DownÊs syndrome in
England and Wales
from 1989 to 1998
Notification of DownÊs
syndrome
Collection of reports from all
regional cytogenetic
laboratories of cases found to
have a DownÊs syndrome
karyotype
Incidence of DownÊs
syndrome per 10,000 live
and still births
Observed odds of maternal
age specific risk of DownÊs
syndrome
1986: 6.7
1988 6. 1.
1990: 5.9
1992: 5.7
1994: 4.7
1996: 5.5
1998: 6.2
Odds at age 20 years: 1:1441
Odds at age 25 years: 1:1383
Odds at age 30 years: 1:959
Odds at age 35 years: 1:338
Odds at age 40 years: 1:84
Odds at age 45 years: 1:32
Report of child health
statistics
An estimated 6% of
births with DownÊs
syndrome are missed by
the National Down
Syndrome Cytogenetic
Register, therefore, the
number of births was
increased by 6% to
allow for those not
included
What is the sensitivity, specificity, detection rate or false positive rate of different screening methods?
Study Ref Population Intervention Outcomes Results Comments Study
Smith-
Bindman
et al., 2001
4 [315] 56 studies, 130,365
unaffected fetuses
and 1930 cases of
DownÊs syndrome
Systematic review;
Articles that assessed
second trimester (15 to
24 weeks) ultrasound
markers (choroid plexus
cyst, nuchal fold
thickening, echogenic
Sensitivity and specificity of
each ultrasonographic
marker and associated fetal
loss per case diagnosed
Nuchal fold (95% CI):
Sensitivity 0.04 (0.02 to
0.10)
Specificity 0.99 (0.99 to
0.99)
Fetal loss 0.6
EL
type
SV 3
SV 3
type
EL
SR 2b
& 3