Plasma concentrations of angiogenic/anti-angiogenic factors have prognostic value in women presenting with suspected preeclampsia to the obstetrical triage area: a prospective study

Figures & data

Table 1. Demographic/clinical characteristics, maternal morbidity and adverse neonatal outcome by study groups.

	Stable until delivery at term (n = 37)	Developed PE requiring preterm delivery (n = 48)	p
Age (years)	26 (19.5–32.5)	26.5 (21.0*33.8)	0.6
African American	34 (91.9%)	44 (91.7%)	0.9
Nulliparous	16 (43.2%)	20 (41.7%)	0.8
Previous preeclampsia	7/21 (33.3%)	12/28 (42.9%)	0.5
Smoking	6 (16.2%)	5 (10.4%)	0.4
Body mass index (kg/m^2)	32.0 ± 7.7	30.9 ± 8.2^α	0.5
Chronic hypertension	18 (48.6%)	22(45.8%)	0.8
Pregestational diabetes	2 (5.4%)	3 (6.3%)	0.9
Chief complaint in triage area
Elevated blood pressure	31 (84%)	47 (97.9%)	0.04
Proteinuria	8 (21.6%)	10 (20.8%)	0.9
Edema	2 (5.4%)	7 (14.6%)	0.3
Headache	15 (40.5%)	22 (45.8%)	0.6
GA at venipuncture (weeks)	35.0 (32.3–35.9)	32.9 (30.1–35.4)	0.1
Average blood pressure in triage area
Systolic (mmHg)	135 ± 11	158 ± 16	<0.001
Diastolic (mmHg)	82 ± 8	97 ± 11	<0.001
Mean arterial (mmHg)	100 ± 8	117 ± 11	<0.001
Proteinuria in triage area	11 (29.7%)	37 (77.1%)	<0.001
Interval to delivery (days)	25 (13–46)	3 (1–9)	<0.001
GA at delivery (weeks)	38.3 (37.1–39.0)	34.7 (32.1–36.1)	<0.001
Birthweight (g)	3056 ± 483	1866 ± 625	<0.001
<10%	6 (16.2%)	19 (39.6%)	0.02
Adverse maternal and neonatal outcome
Indicated preterm delivery <34 weeks	–	20 (41.7%)	<0.001
Fetal death	1 (2.1%)	–	0.4
Maternal morbidity
Eclampsia (at term)	1 (2.7%)	–	0.4
HELLP	–	1 (2.1%)	1.0
Pulmonary edema	–	2 (4.2%)	0.5
Oliguria	–	6 (12.5%)	0.03
Serum Creatinine >1.2 mg/dL	–	5 (10.4%)	0.06
Abruptio placentae	2 (5.4%)	5 (10.4%)	0.5
Elevated AST	3 (8.1%)	7 (14.6%)	0.5
Thrombocytopenia	–	3 (6.3%)	0.3
Antepartum admission to ICU	–	7 (14.6%)	0.02
Composite adverse maternal outcome	5 (13.5%)	24 (50%)	<0.001
Neonatal complications
Fetal or neonatal death	1 (2.1%)	–	0.4
RDS	3 (8.1%)	8 (16.7%)	0.3
BPD	–	3 (6.3%)	0.2
IVH	2 (5.4%)	4 (8.3%)	0.5
Adverse neonatal outcome	4 (10.8%)	10 (20.8%)	0.2
Composite maternal morbidity  and/or adverse neonatal outcome	8 (21.6%)	29 (60.4%)	<0.001

α: n = 47; value expressed as median (interquartile), mean ± SD or number (%).

PE, preeclampsia; GA, gestational age; AST, aspartate amniotransferase; ICU, intensive care unit; RDS, respiratory distress syndrome; BPD, bronchopulmonary dysplasia; IVH, intraventricular hemorrhage.

Three patients in Group I delivered preterm: two due to spontaneous preterm delivery, and another one due to anti-D isoimmunization. One patient in Group I was diagnosed with chronic hypertension and superimposed preeclampsia at 35 weeks and 4 days. She was discharged home on the same day and had placental abruption with a fetal death at 37 6/7 weeks.

Figure 1. Median maternal plasma Multiple of Median (MoM) concentrations of soluble vacular endothelial growth factor receptor (sVEGFR)-1, soluble endoglin (sEng), sVEGFR-2, placental growth factor (PlGF), PlGF/sVEGFR-1 ratio and PlGF/sEng ratio in patients who subsequently developed severe PE requiring preterm delivery and those who remained stable until term [sVEGFR-1: median 4.46 MoM, interquartile range (IQR) 2.5–9.8 MoM vs. 1.5 MoM, IQR 0.9–2.4 MoM; p < 0.001; sEng: median 3.3 MoM, IQR 2.1–5.6 MoM vs. 1.2 MoM, IQR 0.9–1.7 MoM; p < 0.001; sVEGFR-2: median 0.69 MoM, IQR 0.5–0.9 MoM vs. 0.9 MoM, IQR 0.7–1.1 MoM; p < 0.001; PlGF: median 0.15 MoM, IQR 0.08–0.23 MoM vs. 0.47 MoM, IQR 0.3–1.1 MoM; p < 0.001; PlGF/sVEGFR-1: median 0.03 MoM, IQR 0.008–0.07 MoM vs. 0.4 MoM, IQR 0.2-0.9 MoM; p < 0.001; PlGF/sEng: median 0.04 MoM, IQR 0.01–0.09 MoM vs. 0.4 MoM, IQR 0.2–0.9 MoM; p < 0.001].

Table 2. Diagnostic performance of plasma concentrations of angiogenic/anti-angiogenic factors for the identification of patients who subsequently developed severe preeclampsia requiring preterm delivery.

	Cut-off (MoM) from ROC curves in previous publication	Sensitivity (%)	Specificity (%)	LR for a positive test (95% CI)	Posterior probability (95% CI)	LR of a negative test (95% CI)	Posterior probability (95% CI)
sVEGFR-1	≥3.46	58.3 (28/48)	86.5 (32/37)	4.3 (1.9–10)	85% (71–93)	0.48 (0.3–0.7)	38% (31–47)
sEng	≥2.7	64.6 (31/48)	91.9 (34/37)	7.9 (2.6–24)	91% (77–97)	0.39 (0.3–0.6)	34% (25–43)
PlGF	≤0.4	91.7 (44/48)	62.2 (23/37)	2.4 (1.6–3.7)	76% (67–83)	0.13 (0.05–0.4)	14% (6–31)
sVEGFR-2	≤0.74	56.3 (27/48)	67.6 (25/37)	1.7 (1.02–2.9)	69% (57–79)	0.65 (0.4–0.9)	46% (36–55)
PlGF/sVEGFR-1	≤0.05	66.7 (32/48)	91.9 (34/37)	8.2 (2.7–25)	91% (78–97)	0.36 (0.2–0.6)	32% (24–42)
PlGF/sEng	≤0.07	66.7 (32/48)	91.9 (34/37)	8.2 (2.7–25)	91% (78–97)	0.36 (0.2–0.6)	32% (24–42)

Prevalence of severe preeclampsia requiring preterm delivery = 56.5% (48/85).

Value expressed as % (n/N).

MoM, multiples of the median; ROC, receiver-operating characteristic; LR, Likelihood Ratio; CI, confidence interval; PlGF, Placental Growth Factor, sEng, soluble endoglin, sVEGFR-1, soluble vascular endothelial growth factor receptor-1, sVEGFR-2, soluble vascular endothelial growth factor receptor-2.

Figure 2. Area under the Receiver-Operating Characteristic (ROC) curves for angiogenic/anti-angiogenic factor ratio Multiples of the Median (MoM) compared to mean arterial pressure and combined standard tests (mean arterial pressure, serum creatinine, serum uric acid, aspartate aminotransferase, platelet count) for the identification of patients who delivered within 2 weeks (A) Restricted to patients who presented before 34 weeks of gestation; and (B) Included all patients in the cohort.

Table 3. Likelihood (unadjusted and adjusted) of each outcome according to angiogenic/antiangiogenic factors ratio.

	Outcome				Unadjusted			Adjusted-I (Full)			Adjusted-II (Reduced)
	No		Yes
Outcome - Predictor	%	n/N	%	n/N	OR	95% CI		OR	95% CI		OR	95% CI
Indicated Preterm Delivery due to PE
PlGF/sVEGFR-1 MoM ≤0.05	8.1	3/37	66.7	32/48	22.7	6.0	85.2	7.1	1.3	39.7	7.4*	1.6	34.1
PlGF/sEng MoM ≤0.07	8.1	3/37	66.7	32/48	22.7	6.0	85.2	8.0	1.5	42.9	8.8*	1.9	40.2
Maternal morbidity
PlGF/sVEGFR-1 MoM ≤0.05	32.1	18/56	58.6	17/29	3.0	1.2	7.6	2.2	0.7	7.3	3.7^α	1.4	10.0
PlGF/sEng MoM ≤0.07	32.1	18/56	58.6	17/29	3.0	1.2	7.6	2.3	0.7	7.1	2.4^β	0.8	7.3
Adverse neonatal outcome
PlGF/sVEGFR-1 MoM ≤0.05	33.8	24/71	78.6	11/14	7.2	1.8	28.2	6.4	0.9	44.9	10.0^γ	2.0	48.9
PlGF/sEng MoM ≤0.07	33.8	24/71	78.6	11/14	7.2	1.8	28.2	5.9	0.9	37.7	10.1^γ	2.1	49.8
Composite maternal morbidity and/or  adverse neonatal outcome
PlGF/sVEGFR-1 MoM ≤0.05	17.4	4/23	65.0	13/20	8.8	2.1	36.4	8.6	0.8	90.7	2.8*	0.9	8.8
PlGF/sEng MoM ≤0.07	17.4	4/23	65.0	13/20	8.8	2.1	36.4	5.9	0.8	45.7	3.1*	1.0	9.5

OR, odds ratio, CI, confidence interval; PE, preeclampsia; PlGF, placental growth factor, sEng, soluble endoglin; sVEGFR-1, soluble vascular endothelial growth factor receptor-1; ORs represent the likelihood of outcome among subjects exhibiting analyte ratio concentrations below centile cutoff relative to the likelihood of outcome among subjects at or above cutoff; Adjusted-I (Full) models included age, African American ethnicity, chronic hypertension, mean arterial pressure, and combined nulliparity/previous preeclampsia; Adjusted- II (Reduced) models include final multivariable adjustment after excluding factors that were not significantly associated with the dependent variable from the Full model- variables included are indicated as follows:

*adjusted for average mean arterial pressure.

α: adjusted for nulliparity, previous preeclampsia.

β: adjusted for nulliparity, previous preeclampsia, average mean arterial pressure.

γ: adjusted for gestational age at blood sampling.

Table 4. Demographic/clinical characteristics and adverse maternal and neonatal outcomes of the patients who presented to the triage area at <34 weeks according to interval to delivery within and more than 2 weeks.

	Delivery more than 2 weeks (n = 25)	Delivery within 2 weeks (n = 18)	p
Age (years)	29 (20–36)	24.5 (19–31)	0.1
African American	23 (92.0%)	16 (88.9%)	1.0
Nulliparous	11 (44.0%)	9 (50.0%)	0.8
Previous preeclampsia	4/14 (28.6%)	5/9 (55.6%)	0.4
Smoking	3 (12.0%)	1 (5.6%)	0.6
Body mass index (kg/m^2)	34.0 ± 7.1	31.2 ± 9.5	0.4
Chronic hypertension	16 (64.0%)	7 (38.9%)	0.1
Pre-gestational diabetes	1 (4.0%)	0	1.0
Chief complaint in triage area
Elevated blood pressure	22 (88%)	18 (100%)	0.3
Proteinuria	7 (28.0%)	4 (22.2%)	0.7
Edema	2 (8.0%)	1 (5.6%)	1.0
Headache	10 (40.0%)	7 (38.9%)	0.9
GA at blood sampling (weeks)	30.6 (27.6–33.0)	31.5 (29.0–32.3)	0.9
Average blood pressure in triage area
Systolic (mmHg)	145 ± 17	160 ± 18	0.005
Diastolic (mmHg)	85 ± 9	102 ± 14	<0.001
Mean arterial (mmHg)	105 ± 8	117 ± 11	<0.001
Proteinuria in triage area	3 (20%)	19 (67.9%)	0.003
Platelet count	237 (190–278)	192 (172–235)	0.09
AST	19 (14–34)	23 (18–34)	0.1
Serum creatinine (mg/dL)	0.6 (0.6–0.7)	0.7 (0.6–0.7)	0.08
Serum uric acid (mg/dL)	3.4 (3.0–3.8)α	4.9 (3.9–5.5)β	0.001
Hospitalized	15 (60%)	18 (100%)	0.002
Interval to delivery (days)	41 (22–65)	3 (2–6)	<0.001
GA at delivery (weeks)	37 (35.3–38.9)	32 (29.7–32.7)	<0.001
Birthweight (g)	2767 ± 730	1283 ± 384	<0.001
Adverse maternal and neonatal outcomes
Indicated preterm delivery <34 weeks	2 (8%)	18 (100%)	<0.001
Maternal morbidity at 2 weeks
Eclampsia	–	–
HELLP	–	–
Pulmonary edema	–	–
Oliguria	–	3 (16.7%)	0.06
Serum Creatinine >1.2 mg/dL	–	1 (5.6%)	0.4
Abruptio placentae	–	1 (5.6%)	0.4
Elevated AST	–	4 (22.2%)	0.025
Thrombocytopenia	–	–	–
Antepartum admission to ICU	–	3 (16.7%)	0.06
Fetal Death	–	–
Composite adverse maternal outcome	–	9 (50%)	<0.001
Neonatal complications at 2 weeks
Neonatal death	–	–	–
RDS	–	6 (33.3%)	0.003
BPD	–	3 (16.7%)	0.06
IVH	–	3 (16.7%)	0.06
Adverse neonatal outcome	–	8 (44.4%)	<0.001
Composite maternal morbidity and/or  adverse neonatal outcome	–	13 (72.2%)	<0.001

Value expressed as median (interquartile), mean ± SD or number (%); GA, gestational age; AST, aspartate amniotransferase; ICU, intensive care unit; RDS, respiratory distress syndrome; BPD, bronchopulmonary dysplasia; IVH, intraventricular hemorrhage.

Table 5. Diagnostic performance of plasma concentrations of angiogenic/anti-angiogenic factors among patients who presented at <34 weeks of gestation for the identification of patients who subsequently delivered within 2 weeks.

	Cut-off (MoM) derived from ROC curves in previous publication	Sensitivity (%)	Specificity (%)	LR for a positive test (95% CI)	Posterior probability (95% CI)	LR of a negative test (95% CI)	Posterior probability (95% CI)
sVEGFR-1	≥4.0	78 (14/18)	96 (24/25)	19 (2.8–135)	93% (67–99)	0.23 (0.1–0.6)	14% (7–28)
sEng	≥3.0	83 (15/18)	96 (24/25)	21 (3.0–144)	94% (69–99)	0.17 (0.06–0.5)	11% (4–26)
PlGF	≤0.15	72 (13/18)	92 (23/25)	9 (2.3–35)	87% (63–96)	0.3 (0.1–0.6)	18% (9–32)
sVEGFR-2	≤0.74	72 (13/18)	72 (18/25)	2.6 (1.3–5.2)	65% (48–79)	0.39 (0.2–0.8)	22% (11–38)
PlGF/sVEGFR-1	≤0.035	89 (16/18)	96 (24/25)	22 (3.2–153)	94% (70–99)	0.12 (0.03–0.4)	8% (2–24)
PlGF/sEng	≤0.05	89 (16/18)	96 (24/25)	22 (3.0–153)	94% (70–99)	0.12 (0.03–0.4)	8% (2–24)

Prevalence of patients who subsequently delivered within 14 days = 41.9% (18/43).

Value expressed as % (n/N); MoM, multiples of the median; ROC, receiver-operating characteristic; LR, Likelihood Ratio; CI, confidence interval; PlGF, Placental Growth Factor, sEng, soluble endoglin, sVEGFR-1, soluble vascular endothelial growth factor receptor-1; sVEGFR-2, soluble vascular endothelial growth factor receptor-2.

Table 6. Likelihood (unadjusted and adjusted) of selected pregnancy outcomes according to angiogenic/antiangiogenic factor ratio in patients who presented to the triage area at <34 weeks of gestation.

	Outcome				Unadjusted			Adjusted
	No		Yes
Outcome - Predictor	%	n/N	%	n/N	OR	95% CI		OR	95% CI
Delivery within 2 weeks
PlGF/sVEGFR-1 MoM ≤0.035	4	1/25	88.9	16/18	192.0	16.0	>999.999	53.7	5.9	485.8
PlGF/sEng MoM ≤0.05	4	1/25	88.9	16/18	192.0	16.0	>999.999	58.3	6.3	538.5
Week 2 maternal morbidity
PlGF/sVEGFR-1 MoM ≤0.035	26.5	9/34	88.9	8/9	22.2	2.4	203.3	10.1	1.3	80.8
PlGF/sEng MoM ≤0.05	26.5	9/34	88.9	8/9	22.2	2.4	203.3	9.4	1.2	72.0
Week 2 adverse neonatal outcome					Insufficient variation to model
PlGF/sVEGFR-1 MoM ≤0.035	25.7	9/35	100	8/8
PlGF/sEng MoM ≤0.05	25.7	9/35	100	8/8
Week 2 composite maternal morbidity  and/or adverse neonatal outcome
PlGF/sVEGFR-1 MoM ≤0.035	16.7	5/30	92.3	12/13	60.0	6.3	571.9	19.5	2.5	150.1
PlGF/sEng MoM ≤0.05	16.7	5/30	92.3	12/13	60.0	6.3	571.9	19.5	2.6	144.1

OR, odds ratio, CI, confidence interval; PlGF, placental growth factor, sEng, soluble endoglin, sVEGFR-1, soluble vascular endothelial growth factor receptor-1. ORs represent the likelihood of outcome among subjects exhibiting analyte ratio concentrations below centile cutoff relative to the likelihood of outcome among subjects at or above cutoff; Adjusted models included accounted for the association between mean arterial pressure and the outcome variable, Firth’s penalized maximum likelihood estimation was also used due to small sample size.

Figure 3. Addition of the PlGF/sVEGFR-1 ratio to standard tests significantly improved the sensitivity at a fixed false-positive rate of 3% (p = 0.004) and marginally improved sensitivity at a fixed false-positive rate of 5% (p = 0.06) for the identification of patients who would be delivered due to preeclampsia within 2 weeks.

Table 7. Sensitivities of each outcome according to angiogenic/antiangiogenic factors ratio in patients who presented to the triage area at <34 weeks of gestation while fixing different false positive rates (FP).

	Sensitivities (%) at fixed false positive rates (%)
Outcome - Predictor	FP: 3%	95% CI		FP: 5%	95% CI		FP: 10%	95% CI
Delivery with 14 Days
PlGF/sVEGFR-1	72.2	46.5	90.3	88.9	65.3	98.6	88.9	65.3	98.6
PlGF/sEng	77.8	52.4	93.6	88.9	65.3	98.6	88.9	65.3	98.6
Systolic blood pressure (mmHg)	22.2	6.4	47.6	44.4	21.5	69.2	44.4	21.5	69.2
Serum AST	16.7	3.6	41.4	16.7	3.6	41.4	16.7	3.6	41.4
Serum creatinine (mg/dL)	11.1	1.4	34.7	22.2	6.4	47.6	55.6	30.8	78.5
Mean arterial pressure (mmHg)	5.6	0.1	27.3	44.4	21.5	69.2	44.4	21.5	69.2
Diastolic blood pressure (mmHg)	5.6	0.1	27.3	44.4	21.5	69.2	55.6	30.8	78.5
Serum uric acid (mg/dL)	0.0			11.8	1.5	36.4	70.6	44.0	89.7
Platelet counts	0.0			0.0			5.6	0.1	27.3
Proteinuria	0.0			0.0			0.0
Week 2 composite maternal morbidity  and/or adverse neonatal outcome
PlGF/sVEGFR-1	46.2	19.2	74.9	92.3	64.0	99.8	92.3	64.0	99.8
PlGF/sEng	61.5	31.6	86.1	92.3	64.0	99.8	92.3	64.0	99.8
Serum uric acid (mg/dL)	15.4	1.9	45.4	23.1	5.0	53.8	46.2	19.2	74.9
Systolic blood pressure (mmHg)	30.8	9.1	61.4	53.8	25.1	80.8	61.5	31.6	86.1
Diastolic blood pressure (mmHg)	53.8	25.1	80.8	53.8	25.1	80.8	61.5	31.6	86.1
Mean arterial pressure (mmHg)	15.4	1.9	45.4	53.8	25.1	80.8	61.5	31.6	86.1
Serum creatinine (mg/dL)	30.8	9.1	61.4	53.8	25.1	80.8	53.8	25.1	80.8
Serum AST	23.1	5.0	53.8	23.1	5.0	53.8	23.1	5.0	53.8
Platelet counts	0.0			7.7	0.2	36.0	7.7	0.2	36.0
Proteinuria	0.0			0.0			0.0

PlGF, placental growth factor; sEng, soluble endoglin; sVEGFR-1, soluble vascular endothelial growth factor receptor-1; AST, aspartate aminotransferase.

Figure 4. Kaplan–Meier survival curves by angiogenic/anti-angiogenic ratio Multiple of Median (MoM) cut-offs of patients who delivered prior to 37 weeks of gestation (right censored). Patients who delivered preterm due to causes other than PE had the interval between blood draw and delivery treated as a censored observation. (A = PlGF/sVEGFR-1; B = PlGF/sEng).

Table 8. Disposition of the patient after visiting the triage area (hospitalization versus discharge home), rate of preterm delivery and adverse perinatal outcomes according to the previously proposed grading of severity criteria based on plasma MoM concentrations of the PlGF/sVEGFR-1 ratio and the PlGF/sEng ratio.

	PlGF/sVEGFR-1 Ratio (MoM)			PlGF/sEng Ratio (MoM)
	≥0.35, Zone 1 (n = 15)	0.0351-0.349 Zone 2 (n = 11)	≤0.035 Zone 3 (n = 17)	≥0.30 Zone 1 (n = 18)	0.051-0.299 Zone 2 (n = 8)	≤0.05 Zone 3 (n = 17)
Home (Column %)	4 (26.7%)	5 (45.5%)	1 (5.9%)	6 (33.3%)	4 (50.0%)	0
Hospitalized (Column %)	11 (73.3%)	6 (54.5%)	16 (94.1%)	12 (66.7%)	4 (50.0%)	17 (100%)
Risk category Number (Row %)	Low	Intermediate	High	Low	Intermediate	High
	15 (34.9%)	11 (25.6%)	17 (39.5%)	18 (41.9%)	8 (18.6%)	17 (39.5%)
Delivery <34 weeks	6.7% (1/15)	27.3% (3/11)	94.1% (16/17)	5.6% (1/18)	25.0% (2/8)	100% (17/17)
Delivery within 14 days	6.7% (1/15)	9.1% (1/11)	94.1% (16/17)	5.6% (1/18)	12.5% (1/8)	94.1% (16/17)
Delivery within 7 days	6.7% (1/15)	– (0/11)	88.2% (15/17)	5.6% (1/18)	12.5% (1/8)	82.4% (14/17)
Maternal morbidity (within 2 weeks)	6.7% (1/15)	0	47.1% (8/17)	5.6% (1/18)	0 (0/8)	47.1% (8/17)
Adverse neonatal outcome (within 2 weeks)	0	0	47.1% (8/17)	0	0	47.1% (8/17)
Composite maternal morbidity and/or  adverse neonatal outcome (within 2 weeks)	6.7% (1/15)	0	70.6% (12/17)	6.7% (1/15)	0	70.6% (12/17)

Value expressed as % (n/N) PlGF, Placental Growth Factor, sEng, soluble endoglin, sVEGFR-1, soluble vascular endothelial growth factor receptor-1.