The demographic characteristics of participants are shown in Table I. Mean age was 31.6 ± 4.9 years,
and about half (48%) of them were nulliparous.
Table 1: Demographic characteristics of the study population
Characteristics
|
N=170
|
Age (years) mean ( ± SD)
|
31.57 ±4.98
|
18-28 years
|
50 (27.3)
|
19-39 years
|
125 (68.3)
|
>40
|
8 (4.4)
|
Parity n (%)
|
|
Nulliparous
|
88 (48.1)
|
1-4
|
95 (51.4)
|
Multiparous
|
1(0.5)
|
BMI mean ( ±SD)
|
30.08±5.15
|
Previous PrE n (%)
|
7 (4)
|
Previous GDM n (%)
|
5(2.8)
|
Thirteen women(8%) developed PrE (Fig. 3).
There was significant association between the PI test (X2 = 16.29 p = 0.00),
S/D test (X2 = 8.55,
p = 0.003) and a combined test (X2 = 11.5,
p = 0.001) with development of PrE (Table 2).
Table 2: Association between Doppler test results and development of PrE
|
|
Outcome
|
Total N(%)
|
X2 (p-value)
|
|
|
Yes N(%)
|
No N(%)
|
PI TEST
|
ABNORMAL
|
5(41.7%)
|
7(58.3%)
|
12(100)
|
16.29(0.000)*
|
NORMAL
|
8(5.1)
|
150(94.9)
|
158(100)
|
|
|
|
|
|
|
|
RI TEST
|
ABNORMAL
|
3(15.0)
|
17(85.0)
|
20(100)
|
0.76 (0.39)
|
NORMAL
|
10(6.7)
|
140(93.3)
|
150(100)
|
|
|
|
|
|
|
|
S/D TEST
|
ABNORMAL
|
6(24.0)
|
19(76.0)
|
25(100)
|
8.55 (0.003)*
|
NORMAL
|
7(4.8)
|
138(95.2)
|
145(100)
|
|
|
|
|
|
|
|
NOTCH TEST
|
PRESENT
|
3(21.4)
|
11(78.6)
|
14(100)
|
2.25(0.133)
|
ABSENT
|
10(6.4)
|
146(93.6)
|
156(100)
|
|
|
|
|
|
|
|
COMBINED TEST
|
ABNORMAL
|
7(25.0)
|
21(75.0)
|
28(100)
|
11.5(0.001)*
|
NORMAL
|
6(4.2)
|
136(95.8)
|
143(100)
|
|
Fig. 4 displays the screening characteristics of uterine Doppler for PrE. The combined test result had the highest sensitivity of 53.8%. Specificity was high for all indices with PI having the highest specificity of 95.5%.
Patients without uterine artery notching were 3 times less likely to develop PrE than counterparts with notching (95% CI: 1.04 -10.76). All the tests had high negative predictive values (NPV) for PrE,
while positive predictive value was highest (41.7%) for PI >95th centile.
Fig. 5 shows the Receptor-Operator Curves while Fig. 6 shows the corresponding areas under the curves (AUC) of the various Doppler indices for prediction of PrE. The combined test had the best predictive performance with an AUC of 0.71 (95% CI: 0.534 - 0.871) while UtAD RI was least performing with AUC of 0.56 (95% CI: 0.388 - 0.735) and showed no discriminatory ability (p >0.05).
Five out of the 13 patients developed severe PrE (Fig. 7). Table 3 shows that abnormal PI,
RI,
SD and combined test were significantly associated with severe PrE (p < 0.05),
with PI >95th centile having the strongest association X2 = 14.5,
p= 0.00).
Table 3: Relationship of uterine artery indices with severity of pre-eclampsia
|
|
Severe PrE
|
X2 (p-value)
|
|
|
Yes N(%)
|
No
N(%)
|
Total N(%)
|
PI TEST
|
ABNORMAL
|
3(25.0)
|
9(75.0)
|
12(100.0)
|
14.47(0.00)*
|
NORMAL
|
2(1.3)
|
156(98.7)
|
158(100.0)
|
|
|
|
|
|
|
RI TEST
|
ABNORMAL
|
3(15.0)
|
17(85.0)
|
20(100.0)
|
7.25(0.01)*
|
NORMAL
|
2(1.3)
|
148(98.7)
|
150(100.0)
|
|
|
|
|
|
|
S/D TEST
|
ABNORMAL
|
3(12.0)
|
22(88.0)
|
25(100.0)
|
5.17 (0.02)*
|
NORMAL
|
2(1.4)
|
143(98.6)
|
145(100.0)
|
|
|
|
|
|
|
NOTCH TEST
|
PRESENT
|
2(15.4)
|
11(84.6)
|
13(100.0)
|
3.65(0.06)
|
ABSENT
|
3(1.9)
|
154(98.1)
|
157(100.0)
|
|
|
|
|
|
|
COMBINED TEST
|
ABNORMAL
|
4(14.3)
|
24(85.7)
|
28(100.0)
|
10.73 (0.00)*
|
NORMAL
|
1(0.7)
|
141(99.3)
|
142(100.0)
|
The accuracy of the UtAD indices for severe PrE is shown in Fig. 8. There was an increase in sensitivity for all indices,
with the S/D test having the highest sensitivity (80%),
specificity of 87.3%,
NPV of 99.3%,
and PPV of 16.0%.
Patients with an abnormal PI result were the most likely to develop severe PrE (Positive Likelihood ratio = 1.33,
95% CI: 0.96 -1.83),
while patients with a normal S/D ratio were least likely to develop severe PrE (Negative LR = 0.04,
95% CI: 0.01 -0.37).The ROCs (Fig. 9) show the corresponding increase in sensitivity.
There was also increase AUC for prediction of severe PrE (Fig. 10) for all indices. A combined test result had the highest AUC of .830 (95% CI: 0.624 - 1.000) while UtA notching had the least AUC of 0.688 (95% CI: 0.383 - 0.954).