Table 1.

Model inputs (epidemiology and patient flow probabilities)

Variables	Base value	Range
Epidemiology
Total number of pregnancies reaching 10 weeks GA	131,567 [4]	105,254–157,880a
Singleton pregnancies, %	98.20 [4]	78.60–100.0%a
Incidence of T21, T18, and T13 – first trimester, %	0.298, 0.202, 0.136 [20]	±20%a
Incidence of T21, T18, and T13 – second trimester, %	0.202, 0.045, 0.013[20]	±20%a
Clinical practice
Prenatal screening uptake, %	78.87 [4]	63.10–94.64a
Screened women receiving the following tests by screening algorithm, %
Conventional screening
FTS	78.10 [4]	62.48–93.72a
STS	21.90[4]	1-FTS
Invasive testing without prior screening	1 [4]	0.70–1.04a
Invasive testing following positive screen [4]	87.50	70.00–100a
NIPT primary screening
NIPT test	100	−
Invasive testing without prior screening	0 [4]	0–0.87 [4]
Invasive testing following positive screening	87.50 [4]	70.00–100a
“No result” rate - 1st draw	3.00 [21]	2.40–3.60a
“No result” rate - 2nd draw	37.00 [21]	29.60–44.40a
Second “no result” to invasive testing (remainder to conventional screening)	30.00b	0–100
Percentage of positive results receiving genetic counseling prior to invasive testing	15.00b	12.00–18.00a
Procedure-related miscarriage	0.50 [22]	0.50–1.00b
Procedure-related leakage of amniotic fluid	1.00 [4]	0.80–1.20a
Additional rare complications of invasive testing	1.00b	0.80–1.20a

FTS, first-trimester screening; GA, gestational age; NIPT, noninvasive prenatal testing; STS, second-trimester screening.

^aSensitivity range of ±20%; does not exceed 100% nor the lower bound of 0%.

^bModel assumption based on expert opinion.