The National Screening Committee in the United Kingdom recommends that all pregnant women be offered a screening test for Down syndrome. Women who have a high-risk result are then offered chorionic villus sampling or amniocentesis, but these invasive tests carry a risk of miscarriage and cannot be performed until 10 weeks of gestation. Validity studies have assessed the technology for noninvasive prenatal diagnosis (NIPD) for Down syndrome. An NIPD test using cell-free fetal DNA eliminates the risk of miscarriage associated with invasive testing. Other attributes of NIPD included its accuracy and timing in pregnancy because it can be performed somewhat earlier than invasive tests. Another important difference between NIPD and invasive tests is the fact that NIPD provides targeted information (trisomy 21 only or trisomies 21, 18, and 13 only) as compared with an invasive test where information on all chromosomes can be provided. Understanding which attributes are most highly valued by patients and health professionals will help guide the implementation of NIPD. Discrete choice experiments are used to examine stakeholder preferences, in which hypothetical health care options are presented and participants are asked to choose between them. This study was designed to compare the preferences of women and health professionals for key attributes of diagnostic tests for Down syndrome, considering possible clinical features of NIPD relative to invasive tests.
Pregnant women were recruited from the obstetric ultrasound department at 4 hospitals where they were to have a second- or third-trimester ultrasound scan. They had either declined Down syndrome screening or had already undergone screening and were considered low risk. Women were given the questionnaire and had the option of reading 2 brief information sheets, one describing Down syndrome, current tests for Down syndrome screening/diagnosis, and future noninvasive tests, and the second describing test accuracy. To increase the number of opinions, pregnant and nonpregnant women who were members of the patient support group Antenatal Results and Choices (ARC) were asked to participate. The ARC membership includes women who have had to make decisions about invasive testing following a high-risk result or had to decide on management options after a diagnosis of Down syndrome. Midwives and obstetricians were recruited from 1 London and 4 regional hospitals. Attributes for the discrete choice experiment component of the questionnaire accounted for key differences between NIPD and invasive tests and the associated levels of clinically feasible ranges. The attributes (levels) were accuracy (90%, 95%, 100%); time of results, that is, weeks gestation (9, 11, 13); risk of miscarriage (small risk [1%], no risk); and information gained from the test (Down syndrome, Down syndrome plus additional information). The patient questionnaires asked about which test they would prefer to have and those for health professionals asked about which test they would prefer to offer. Participants were asked to choose test A (95%, 9 weeks, small risk, Down syndrome plus other information), test B (100%, 11 weeks, no risk, Down syndrome only), or neither (women may choose not to have a test). Demographic information was also obtained from participants.
The response rate was 94.9% (318/335) for women recruited through maternity units and 61.5% (32/52) for those recruited through ARC. The response rate for health professionals was 54.5% (193/354). Questionnaires from 335 women and 181 health professionals were included in the final analysis. Sixty-six percent of patients ranked safety highest, whereas 58% of health professionals ranked accuracy as the most important attribute. On regression analysis, both groups preferred a test with greater accuracy, no risk of miscarriage, and full information; time of results indicated the preference for an earlier test. Comparison of regression results confirmed the differences observed from rankings with statistically significant differences for accuracy, timing, and no risk of miscarriage. Women 35 years or older placed a greater emphasis on accuracy than younger women, and women who had undergone Down syndrome screening in their current pregnancy differed from those who had declined Down syndrome screening in the emphasis they placed on test timing and information. Sixteen women (4.78%) but no health professionals chose neither for all options; 110 women (32.84%) and 13 professionals (7.18%) chose tests based on no miscarriage risk; 15 women (4.48%) and 33 professionals (18.2%) chose tests based on highest accuracy; 1 woman (0.30%) and no health professionals chose tests based on earliest timing, and 19 women (5.67%) and 7 health professionals (3.87%) chose tests based on full information being available. Women had a strong preference for a test with no risk of miscarriage, and they were prepared to wait more than twice as long and accept 12% lower accuracy for such a test, whereas health professionals preferred to offer a test that was accurate, even if it had a small risk of miscarriage.
Both women and health professionals preferred safe tests that were conducted early in pregnancy with high accuracy and gave information about other conditions in addition to Down syndrome. Women’s strong preference for tests with no risk of miscarriage demonstrates that consideration for the safety of the fetus can outweigh other test attributes when they make decisions regarding prenatal testing. Effective pretest counseling and informed consent processes are necessary to ensure women understand the test parameters and implications of NIPD.