Table 4.
Factors associated with accuracy of cfDNA positive for T21, 18, 13*
| Composite T21, T18, T13 n=83 |
T21 n=47 |
T18 n=20 |
T13 n=16 |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
| ||||||||||||
| TP | FP | p | TP | FP | p | TP | FP | p | TP | FP | p | |
| n (%) | 61 (73.5) | 22 (26.5) | 39 (83.0) | 8 (17.0) | 13 (65.0) | 7 (35.0) | 7 (43.8) | 9 (56.3) | ||||
| Median age (range) | 39 (30–48) | 36 (29–40) | 0.001 | 39 (30–47) | 35.5 (29–38) | 0.005 | 39 (30–48) | 39 (35–40) | 0.6021 | 39 (35–45) | 37 (30–40) | 0.135 |
| AMA | 56/61 (91.8) | 17/22 (77.3) | 0.120 | 36/39 (92.3) | 5/8 (62.5) | 0.053 | 11/13 (84.6) | 7/7 (100) | 0.521 | 7/7 | 7 (77.8) | 0.475 |
| IVF | 10/60 (16.7) | 2/22 (9.1) | 0.499 | 5/38 (13.2) | 0/8 | 0.569 | 2/13 (15.4) | 1/7 (14.3) | >0.999 | 3 (42.9) | 1 (11.1) | 0.262 |
| Twins | 7/61 (11.5) | 1/22 (4.5) | 0.675 | 4/39 (10.3) | 0/8 | >0.999 | 1/13 (7.7) | 0/7 | >0.999 | 1 (14.3) | 2 (22.2) | >0.999 |
| Laboratory (n) | 0.018 | 0.275 | 0.311 | 0.563 | ||||||||
| 1 (32) | 28 (45.9) | 4 (18.2) | 16 (41.0) | 1 (12.5) | 7 (53.9) | 2 (28.6) | 3 (42.3) | 3 (33.3) | ||||
| 2 (34) | 19 (31.2) | 15 (68.2) | 14 (35.9) | 6 (75.0) | 5 (30.8) | 5 (71.4) | 1 (14.3) | 4 (44.4) | ||||
| 3 (16) | 13 (21.3) | 3 (13.6) | 8 (20.5) | 1 (12.5) | 2 (15.4) | 0 | 3 (42.9) | 2 (22.2) | ||||
| 4 (1) | 1 (16) | 0 | 1 (2.6) | 0 | 0 | 0 | 0 | 0 | ||||
| Platformˆ | 0.661 | >0.999 | 0.521 | 0.596 | ||||||||
| MPS (66) | 47 (77.1) | 19 (86.4) | 30 (76.9) | 7 (87.5) | 11 (84.6) | 7/7 (100) | 4 (57.1) | 7 (77.8) | ||||
| SNP (16) | 13 (21.3) | 3 (13.6) | 8 (20.5) | 1 (12.5) | 2 (15.4) | 0 | 3 (42.9) | 2 (22.2) | ||||
| TS (1) | 1 (16) | 0 | 1 (2.6) | 0 | 0 | 0 | 0 | 0 | ||||
| Serum Screen Positive† | 21/25 (84.0) | 5/16 (31.3) | 0.001 | 16 (94.1) | 1 (14.3) | <0.001 | 3/4 (75.0) | 3/5 (60.0) | >0.999 | 2/4 (50) | 1/4 (25.0) | >0.999 |
| US findings | ||||||||||||
| 1st TM US | 39/57 (68.4) | 1/19 (5.3) | <0.001 | 23/36 (63.9) | 0/8 | 0.001 | 11/13 (84.6) | 1/6 (16.7) | 0.010 | 4/7 (57.1) | 1/6 (16.7) | 0.266 |
| NT >3.5mm | 25/54 (46.3) | 1/19 (5.3) | 0.002 | 13/34 (38.2) | 0/8 | 0.043 | 9/12 (75) | 1/5 (20.0) | 0.101 | 2/7 (28.6) | 1/7 (14.3) | >0.999 |
| 2nd TM US | 5/12 (41.7) | 1/19 (5.3) | 0.022 | 3/6 (50.0) | 0/8 | 0.055 | 0/2 (0) | 1/5 (20.0) | >0.999 | 2/2 (100) | 0/8 (0) | 0.022 |
| Pregnancy Outcome | <0.001 | <0.001 | <0.001 | 0.041 | ||||||||
| TOP | 58/61 (95.1) | 1/22 (4.5) | 37 (94.9) | 0/8 | 13/13 (100) | 1/7 (14.3) | 6/7 (85.7) | 2/9 (22.2) | ||||
| Delivered | 3/61 (4.9) | 19/22 (86.4) | 2 (5.1) | 8 | 0 | 4/7 (57.1) | 1/7 (14.3) | 7/9 (77.8) | ||||
| Lost to follow-up | 0 | 2/24 (9.1) | 0 | 0 | 0 | 2/7 (28.6) | 00 | |||||
Values are n (%) unless otherwise noted. P-values were calculated by Kruskal-Wallis or Fisher’s exact test. Statistically significant p-values (defined as p<0.05) are indicated in bold.
Abbreviations: cfDNA, cell-free fetal DNA; T21, trisomy 21; T18, trisomy 18; T13, trisomy 13; TP, true positive; FP, false positive; AMA, advanced maternal age; IVF, in vitro fertilization; MPS, massive parallel sequencing; SNP, single nucleotide polymorphism; TS, targeted sequencing; TM, trimester; US, ultrasound; NT, nuchal translucency; TOP, termination of pregnancy.
Confirmed by karyotype and/or postnatal evaluation.
As determined by the California state prenatal screening program
MPS is used by Laboratories 1 and 2; SNP sequencing/microarray by Laboratory 3; TS by Laboratory 4.