Predictive value of second-trimester ophthalmic artery Doppler for identifying women at risk for preeclampsia

Table 1 Age distribution of study participants

Age group (yrs)	n (%)
20–30	62 (68.9)
31–40	28 (31.1)
mean ± SD	27.8 ± 4.6
Median (25th–75th percentile)	27.5 (24–32)
Range	20–37

Table 2 Obstetric characteristics of study participants

Characteristic	n (%)
Gravida
1	35 (38.9)
2	33 (36.7)
3	20 (22.2)
4	2 (2.2)
Parity
0	38 (42.2)
1	32 (35.6)
2	19 (21.1)
3	1 (1.1)
Living children
0	38 (42.2)
1	34 (37.8)
2	17 (18.9)
3	1 (1.1)
Abortions
0	78 (86.7)
1	12 (13.3)
Gestational age at enrolment (weeks)
mean ± SD	19.6 ± 0.7
Median (25th–75th percentile)	19.9 (19.1–20)
Range	17–23

Table 3 Distribution of ophthalmic artery Doppler indices according to receiver operating characteristic-derived cut-off values (n = 90)

Parameter	Category	n (%)	mean ± SD
RI	Low RI	46 (51.1)	0.71 ± 0.10
	Not low RI	44 (48.9)
P1	Low P1	4 (4.4)	61.9 ± 14.6 cm/s
	Not low P1	86 (95.6)
PI	Low PI	29 (32.2)	2.0 ± 0.3
	Not low PI	61 (67.8)
P2	High P2	78 (86.7)	33.9 ± 10.2 cm/s
	Not high P2	12 (13.3)
PR	High PR	16 (17.8)	0.5 ± 0.1
	Not high PR	74 (82.2)

Cutoff values for categorization were derived using receiver operating characteristic curve analysis and the Youden index. The following thresholds were used: RI < 0.60, PR > 0.60, PI < 1.80, P1 < 50 cm/second, and P2 > 30 cm/s.

P1: First systolic peak velocity; P2: Second systolic peak velocity; PI: Pulsatility index; PR: Peak ratio; RI: Resistive index.

Table 4 Distribution of normotensive participants and those with preeclampsia

Outcome	n (%)
Normotensive	82 (91.1)
Preeclampsia	8 (8.9)
Total	90 (100.0)

Table 5 Association between ophthalmic artery Doppler indices and the subsequent development of preeclampsia

Parameter	Category	Normotensive, n (%)	Preeclampsia, n (%)	Total, n (%)	P value (distribution)	mean ± SD (preeclampsia)	mean ± SD (normotensive)	P value (mean)
RI	Not low RI	44 (100)	0 (0)	44 (100)	0.006	0.6 ± 0.1	0.7 ± 0.1	0.004
	Low RI	38 (82.61)	8 (17.39)	46 (100)
P1	Not low P1	80 (93.02)	6 (6.98)	86 (100)	0.038	56.8 ± 17.9	62.4 ± 14.3	0.307
	Low P1	2 (50)	2 (50)	4 (100)
PI	Not low PI	59 (96.72)	2 (3.28)	61 (100)	0.012	1.7 ± 0.2	2.0 ± 0.3	0.0003
	Low PI	23 (79.31)	6 (20.69)	29 (100)
P2	Not high P2	12 (100)	0 (0)	12 (100)	0.591	39.9 ± 11.4	33.3 ± 10.0	0.085
	High P2	70 (89.74)	8 (10.26)	78 (100)
PR	Not high PR	74 (100)	0 (0)	74 (100)	< 0.0001	0.70 ± 0.1	0.5 ± 0.1	< 0.0001
	High PR	8 (50)	8 (50)	16 (100)

P1: First systolic peak velocity; P2: Second systolic peak velocity; PI: Pulsatility index; PR: Peak ratio; RI: Resistive index.

Table 6 Diagnostic performance of ophthalmic artery Doppler parameters for predicting preeclampsia

Parameter	Low RI	Low P1	Low PI	High P2	High PR
Sensitivity (95%CI), %	100 (63.1–100)	25.0 (3.2–65.1)	75.0 (34.9–96.8)	100 (63.1–100)	100 (63.1–100)
Specificity (95%CI), %	53.7 (42.3–64.8)	97.6 (91.5–99.7)	71.9 (60.9–81.3)	14.6 (7.8–24.2)	90.2 (81.7–95.7)
AUC (95%CI)	0.77 (0.7–0.9)	0.6 (0.5–0.7)	0.7 (0.6–0.8)	0.6 (0.5–0.7)	0.9 (0.8–0.9)
Positive predictive value (95%CI), %	17.4 (7.8–31.4)	50.0 (6.8–93.2)	20.7 (7.9–39.7)	10.3 (4.5–19.2)	50.0 (24.6–75.4)
Negative predictive value (95%CI), %	100 (91.9–100)	93.0 (85.4–97.4)	96.7 (88.7–99.6)	100.0 (73.5–100.0)	100.0 (95.1–100.0)
Diagnostic accuracy, %	57.8	91.1	72.2	22.2	91.1%

AUC: Area under the curve; CI: Confidence interval; P1: First systolic peak velocity; P2: Second systolic peak velocity; PI: Pulsatility index; PR: Peak ratio; RI: Resistive index.