Table 1. Probability and cost variables.

	Base case	Range	References
Variables
T21 prevalence, 1st trimester	1 in 530	(1 in 450 to 1 in 600)	[18]
T18 prevalence, 1st trimester	1 in 1100	(1 in 900 to 1 in 1500)	[19]
T13 prevalence, 1st trimester	1 in 3500	(1 in 2500 to 1 in 5000)	[19]
FTS performance
Cumulative false-positive rate	5%	(3–7%)	[2]
Sensitivity, T21	85%	(75–90%)	[2]
Sensitivity, T18	84%	(80–90%)	[3]
Sensitivity, T13	84%	(80–90%)	[3]
% patients referred out for screening	35%	(25–50%)	Data on file
NIPT performance
Cumulative false-positive rate	0.3%	(0.1–0.5%)	[6]
Sensitivity, T21	99.0%	(98.0–99.9%)	[6]
Sensitivity, T18	96.8%	(90.0–99.9%)	[6]
Sensitivity, T13	92.1%	(85.0–95.0%)	[6]
Termination rate for T21	75%	(60–90%)	[20]
Termination rate for T18	90%	(80–95%)	[21]
Termination rate for T13	90%	(80–95%)	[21]
Procedure-related miscarriage	0.5%	(0.2–2%)	[9,22]
Costs
NIPT	$400–700	($400–$700)	n/a
1st trimester serum	$48.30	($30–$100)	see text
NT	$122.51	($100–$300)	see text
Invasive procedure	$1300	($500–$2500)	[9]
Office visit with counseling	$120	($80–$200)	[9]
T21 birth	$850 000	($600 000–$1 000 000)	[23]
T18 birth	$50 000	($30 000–$70 000)	[23]
T13 birth	$38 000	($25 000–$50 000)	[23]
Termination	$600	($400–$1000)	[9]