Women and health care professionals' preferences for Down's Syndrome screening tests: a conjoint analysis study.

OBJECTIVE: To describe and compare women and health care professionals' preferences for Down's Syndrome screening tests with different test characteristics. DESIGN: Cross sectional questionnaire based conjoint analysis study. SETTING: London teaching hospital. SAMPLE: 291/383 women in their first or second trimester of pregnancy and 98/122 health care professionals (41 obstetricians, senior house officers and above and 57 qualified midwives) providing care at the same hospital. METHODS: Women completed a questionnaire while attending a clinic visit for a dating scan or a routine 20-week anomaly scan. Health care professionals completed a postal questionnaire. MAIN OUTCOME MEASURES: The relative values participants attach to Down's Syndrome screening test attributes: time of test, detection rate and risk of miscarriage of a baby unaffected by Down's Syndrome as a result of subsequent diagnostic tests. RESULTS: Pregnant women and health care professionals shared broadly similar relative values regarding the importance of safe tests, conducted early and with high detection rates. When asked to choose between different Down's Syndrome screening tests, health care professionals valued earlier tests more highly than did women. CONCLUSIONS: While pregnant women and health care professionals share similar relative values regarding optimal prenatal tests, health care professionals place a higher value on earlier tests. This may result in screening policies that overweight timing in the selection of a test to the relative neglect of tests associated with lower miscarriage rates and higher detection rates but conducted later in pregnancy.