MOMs (multiples of the median) and DADs (discriminant XXXX ): improved specificity and cost-effectiveness of biochemical screening for aneuploidy with DADs.

@entity1 @entity2007 @entity11111 @entity160
OBJECTIVE: Our purpose was to assess the efficacy of double- and triple-screening paradigms for Down syndrome and to develop a more logical, statistical approach to risk prediction that will decrease the cost of screening and allow the incorporation of new parameters appropriately weighted for their contribution. STUDY DESIGN: Data from 24,504 @entity1 who had biochemical screening for Down syndrome by single ( @entity160 ), double ( @entity160 , beta- @entity1 chorionic gonadotropin), or triple screening ( @entity160 , beta- @entity1 chorionic gonadotropin, unconjugated @entity11111 ) who had complete outcome information were analyzed by (1) existing gaussian-based methods, (2) the Glasgow ratio method, and (3) a new statistical approach (i.e., directly adjusted data sets for discriminant @entity2007 [DADs]) RESULTS: By use of individual risk-based thresholds for "at risk" status, both double and triple screening performed far better than single screening, but the percentages of @entity1 at risk varied widely. When the percentages at risk were held constant, the sensitivity of double and triple screenings was similar, suggesting that there are no benefits of using @entity11111 as a third marker. For 25,000 @entity1 the use of only @entity160 and beta- @entity1 chorionic gonadotropin would save about  500,000, with no decrease in sensitivity. With the DADs approach a statistically sound model giving more stable estimates was developed that permits each factor to be analyzed for its own explained proportion of variance and allows each parameter to have different weighting. For this data set the same sensitivity was seen with, conservatively, a 1% reduction in the percentage of @entity1 at risk, which would reduce by 250 the number of amniocenteses, at a further savings of about  400,000. CONCLUSIONS: By use of existing methods, double screening is equally as effective as triple screening, so that the expense of @entity11111 is unnecessary. The DADs approach, by allowing for variable weighting of parameters, lowers the at risk percentage and will permit a much more flexible approach as new parameters become available. Changing to DADs and eliminating @entity11111 should achieve higher specificity for the same sensitivity and save, conservatively, about  900,000 in this series. Extrapolated nationally, if confirmed, the annual savings could approach  72,000,000.
