Uptake of prenatal diagnostic testing and the effectiveness of prenatal screening for Down syndrome (original) (raw)
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BMJ, 2002
Objective To compare the effectiveness of different screening policies for the antenatal detection of Down's syndrome. Design Retrospective six year survey. Setting Maternity units of eight districts. Participants Women who completed their pregnancies between 1 January 1994 and 31 December 1999 (155 501 deliveries). Main outcome measures Cases of Down's syndrome identified before 24 weeks' gestation. Results 335 cases of Down's syndrome were identified, 323 in continuing pregnancies or liveborn children. Of these, 171 were identified antenatally. Seven different screening policies were used, in three principal groups: serum screening offered to all mothers, maternal age with serum screening or nuchal translucency available to limited groups, and maternal age combined with anomaly scans. The districts that used serum screening detected 57%, those using maternal age plus serum or nuchal translucency screening 52%, and those using a maternal age of >35 and anomaly scans detected 54%. The least successful district, which offered amniocentesis only to women aged over 37 years, detected only 31%. If amniocentesis had been offered from 35 years, as in all other districts, the detection rate would have risen to 54%. Across the region 15% (range 12-20%) of pregnant women were 35 years or more at delivery, and 58% (33-69%) of infants with Down's syndrome were born to women in this age range. Conclusions Current additional serum or nuchal translucency screening techniques for antenatal detection of Down's syndrome are less advantageous than previously supposed. More pregnant women were aged over 35 than has been presumed in statistical models used in demonstration projects of serum screening and, as a result, the proportion of affected fetuses in this age group is much greater than predicted.
Genetics in Medicine, 2010
Purpose: To compare the number and types of chromosome abnormalities prenatally diagnosed and the number of invasive procedures between current prenatal testing pathways and a pathway where noninvasive prenatal diagnosis for Down syndrome replaces Down syndrome screening tests. Methods: Numbers and types of chromosome abnormalities for each referral category were extracted from prenatal diagnostic testing reports routinely collected in Victoria, Australia, in 2006 and 2007. These data were then applied to the proposed implementation strategy. Results: If noninvasive prenatal diagnosis for Down syndrome had replaced Down syndrome screening tests in 2006 and 2007, in Victoria, there would have been 25 (7%) additional Down syndrome diagnosed, 6896 (84%) fewer invasive procedures, and 231 (56%) non-Down syndrome chromosome abnormalities no longer detected. These include trisomy 13, trisomy 18, sex chromosome abnormalities, balanced and unbalanced rearrangements, polyploidy, and mosaic results. Conclusions: The potential loss of information about chromosome abnormalities other than Down syndrome with noninvasive prenatal diagnosis compared with full karyotyping with traditional prenatal diagnosis should be considered when planning for the implementation of new technologies. Genet Med 2010:12(5):298 -303.
Prenatal screening for Down's syndrome
Public Health, 2001
The National Screening Committee of the Department of Health has made recommendations to the Government advising that prenatal screening for Down's syndrome should be offered to all pregnant women regardless of their age. As most women over 35 are already offered some form of testing, affected pregnancies in younger women will account for the majority of any increased overall detection rate. Therefore, while a 'screening for all' policy will offer wider reproductive choices to more women, it is likely to specifically increase the number of young women experiencing termination of pregnancy for abnormality. A number of inter-dependent factors predispose some women to high levels of psychological distress following termination, and a combination of these factors is most likely to be found in the very young. In addition, very young women often have little knowledge of prenatal testing and may be more likely to accept screening presented as 'routine' without considering the consequences. At the point where decisions about diagnostic testing or termination are made, more specialised support may be indicated for some very young women. If the UK National Screening Committee's recommendations are taken forward therefore, service providers should ensure suitable support is available for some of their more vulnerable clients.
Maternal serum screening for Down syndrome: are women’s perceptions changing?
BJOG: An International Journal of Obstetrics & Gynaecology, 2007
Objectives To document trends in serum screening for Down's syndrome. Background Trends in the uptake of serum screening for Down syndrome have not been documented in a UK population. Design A retrospective review of the rate of uptake in a unit that has offered serum screening for Down syndrome to all pregnant women. Setting A large north of England hospital that has offered universal Down syndrome screening using the 'triple test' since 1992. Patients A total of 47 998 women who booked for antenatal care. Main outcome measures Uptake of serum screening for Down syndrome. Methods The results of the screening programme were contemporaneously recorded on a computer database, and the study team accessed the data. Results There was a significant reduction in the uptake of serum screening for Down syndrome from a maximum of 82.6% in 1993 to 41.4% in 2005. There was a significant but small trend upwards in the age of women accepting screening and also a significant trend in the increase in the screen-positive rates. Conclusions The reduction in uptake of Down syndrome screening over the past 13 years must be taken into account when planning a screening programme. Other units should be encouraged to review their rate of uptake to determine if our data are representative of a wider trend.
Trade-offs in prenatal detection of Down syndrome
American Journal of Public Health, 1998
OBJECTIVES: This paper presents the results of different screening policies for prenatal detection of Down syndrome that would allow decision makers to make informed choices. METHODS: A decision analysis model was built to compare 8 screening policies with regard to a selected set of outcome measures. Probabilities used in the analysis were obtained from official administrative data reports in Spain and Catalonia and from data published in the medical literature. Sensitivity analyses were carried out to test the robustness of screening policies' results to changes in uptake rates, diagnostic accuracy, and resources consumed. RESULTS: Selected screening policies posed major trades-offs regarding detection rates, false-positive results, fetal loss, and costs of the programs. All outcome measures considered were found quite robust to changes in uptake rates. Sensitivity and specificity rates of screening tests were shown to be the most influential factors in the outcome measures co...
BMJ, 2001
Objective To compare the effects, safety, and cost effectiveness of antenatal screening strategies for Down's syndrome. Design Analysis of incremental cost effectiveness. Setting United Kingdom. Main outcome measures Number of liveborn babies with Down's syndrome, miscarriages due to chorionic villus sampling or amniocentesis, healthcare costs of screening programme, and additional costs and additional miscarriages per additional affected live birth prevented by adopting a more effective strategy. Results Compared with no screening, the additional cost per additional liveborn baby with Down's syndrome prevented was £22 000 for measurement of nuchal translucency. The cost of the integrated test was £51 000 compared with measurement of nuchal translucency. All other strategies were more costly and less effective, or cost more per additional affected baby prevented. Depending on the cost of the screening test, the first trimester combined test and the quadruple test would also be cost effective options. Conclusions The choice of screening strategy should be between the integrated test, first trimester combined test, quadruple test, or nuchal translucency measurement depending on how much service providers are willing to pay, the total budget available, and values on safety. Screening based on maternal age, the second trimester double test, and the first trimester serum test was less effective, less safe, and more costly than these four options.
Understandings of Down's syndrome and their place in the prenatal testing context
2003
Introduction: There is a growing consensus that decisions about prenatal testing should a) be informed, and b) reflect the individual's attitudes and values. Most research has focused on information and attitudes in relation to the tests but there has been little attention given to these factors in relation to the target condition. Aims: This thesis is concerned with informed choice in the context of prenatal testing for Down's syndrome. The main aims were to describe the written information that women receive about Down's syndrome prior to prenatal screening, characterise understandings of Down's syndrome that exist independently of the testing context, and identify the relationships between understandings of Down's syndrome, intentions towards using testing and termination, and actual screening choices. Methods and Results: Study 1 employed a content analysis of information about Down syndrome contained in 80 prenatal screening leaflets. Information about Down's syndrome was low in quantity (the median number of statements was one and 33% percent of leaflets contained no descriptive information on the nature of the condition). The majority of statements (63%) were rated as negative in tone, (25% were rated as neutral and 19% were rated as positive). 89% of the statements were of a medical, clinical or epidemiological nature and 11% concerned social, educational or psychosocial issues associated with Down's syndrome Study 2 used Q methodology to characterise understandings of Down's syndrome. 76 people chosen as being likely to represent a diverse range of views Q sorted 50 beliefs about Down's syndrome. Five statistically independent understandings of the condition were extracted using Principal Components Analysis. There was a consensus across participants on the rights of existing people with Down's syndrome to a good quality of life, but there were significant differences in to how respondents believed they personally would cope with, and adjust to an affected child. Some tentative associations between these five understandings and attitudes towards testing and termination were identified. Study 3 employed a self-completion questionnaire in 197 pregnant women to measure attitudes towards Down's syndrome and intentions to test and terminate for the condition. Serum screening uptake was collected later from patient records. Attitudes towards Down's syndrome were significantly associated with intentions to use screening, diagnostic tests, and termination, and also with actual screening uptake (p < 0.05). However, most women accepted screening tests (77% overall) regardless of whether their attitude towards Down's syndrome was favourable or not. Attitudes towards Down's syndrome were most strongly associated with intentions to terminate 111 a pregnancy for the condition. Women who were uncertain about terminating for Down's syndrome had significantly higher levels of ambivalence in their attitudes towards the condition than women whose behavioural intentions were either `yes' to termination or `no' to termination. Discussion: The findings suggest that a) guidelines regarding informed choice are not being met in the case of written information provided about the target condition and b) screening choices might not always be directly informed either by attitudes towards Down's syndrome or towards termination for the condition. Further investigation into the psychological and situational factors associated with testing and termination choices is recommended.