Use of decision analysis to evaluate patients' choices of diagnostic prenatal test.

Women with a family history of a chromosomal or genetic abnormality must weigh several factors in choosing between amniocentesis and chorionic villus sampling. We compared the prenatal test choices of three such women with those of decision analytic models that incorporated their preferences. Patient preferences were assessed using visual linear rating scales. Threshold analysis was used to determine preference ranges, and stochastic sensitivity analysis to provide confidence levels, for each choice of test. The test choices of patients and decision analytic models agreed in one case, and disagreed in two cases. In one of the latter two cases, stochastic and threshold analyses showed the disagreement to be slight; for small shifts in preference differences for first- vs. second-trimester diagnosis, or first- vs. second-trimester therapeutic abortion, patient and decision model would have agreed. In the other, stochastic analysis showed their differences to be large; there were no thresholds for early diagnosis, or for early therapeutic abortion, that would have led to agreement between patient and model. In the two cases in which patient and decision model agreed or slightly disagreed, the patients had made their own choice of prenatal test. In the case in which patient and decision model strongly disagreed, the patient's physician had shared in the choice of test. Decision analysis can be useful in analyzing prenatal test choices based on individual preferences for pregnancy outcomes. When choices of patients and decision models do not agree, examination of the locus of decision making (patient vs. physician) may help resolve apparent differences.