Original Research
Characterization of the Soluble fms-Like Tyrosine Kinase-1 to Placental Growth Factor Ratio in Pregnancies Complicated by Fetal Growth Restriction Ignacio Herraiz, MD, Lisa Antonia Dröge, MD, Enery Gómez-Montes, Alberto Galindo, MD, and Stefan Verlohren, MD
MD,
Wolfgang Henrich,
MD,
OBJECTIVE: To characterize the values of the soluble fms-like tyrosine kinase-1 (sFlt-1) to placental growth factor (PlGF) ratio in pregnancies with fetal growth restriction with or without concurrent preeclampsia or hemolysis, elevated liver enzymes and low platelets syndrome (HELLP) and in pregnancies with normally grown fetuses with or without concurrent preeclampsia or HELLP.
P,.001) and at or after 34 weeks of gestation (117, 66, 165, and 11, respectively, P,.001). The differences among the case subgroups were not statistically different.
METHODS: This is a case–control study performed in two centers (Berlin and Madrid) consisting of 171 singleton pregnancies complicated by fetal growth restriction (n527), preeclampsia or HELLP (n5105) or preeclampsia or HELLP and fetal growth restriction (n539) pairwise matched by gestational age with 171 healthy control pregnancies. Automated measurement of sFlt-1 and PlGF in maternal serum samples was performed after diagnosis (cases) and in gestational-age matched healthy control samples. Samples were analyzed for two timeframes: before and at or after 34 weeks of gestation.
LEVEL OF EVIDENCE: II
RESULTS: Pregnancies with fetal growth restriction, preeclampsia or HELLP, and preeclampsia or HELLP and fetal growth restriction showed higher median values of sFlt1/PlGF ratio than control pregnancies both before 34 weeks of gestation (90, 231, 514, and 3, respectively, From the Fetal Medicine Unit-SAMID, Department of Obstetrics and Gynaecology, Hospital Universitario 12 de Octubre, Madrid, Spain; and the Department of Obstetrics, Charité University Medicine, Berlin, Germany. Corresponding author: Stefan Verlohren, MD, Department of Obstetrics, Charité University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany; e-mail: [email protected]. Financial Disclosure Dr. Verlohren has received lecture fees, consultancy payments, or both from Roche Diagnostics, ThermoFisherScientific, and Novartis. The other authors did not report any potential conflicts of interest. © 2014 by The American College of Obstetricians and Gynecologists. Published by Lippincott Williams & Wilkins. ISSN: 0029-7844/14
VOL. 124, NO. 2, PART 1, AUGUST 2014
CONCLUSION: Fetal growth restriction is characterized by elevated maternal sFlt-1/PlGF ratio, reaching values as high as those observed in preeclampsia or HELLP. (Obstet Gynecol 2014;124:265–73) DOI: 10.1097/AOG.0000000000000367
A
ngiogenic imbalance has emerged as an essential piece to understand the complex puzzle of placental related disorders, which includes fetal growth restriction and preeclampsia. A failure in trophoblast invasion leads to an altered placental production and systemic release of antiangiogenic factors such as soluble fms-like tyrosine kinase-1 (sFlt-1) and proangiogenic factors such as placental growth factor (PlGF).1 There is evidence that angiogenic imbalance, expressed by an increased sFlt-1/PlGF ratio, is present in early-onset fetal growth restriction and in early-onset preeclampsia2–4 supporting that both represent two similar pathophysiologic states.5,6 In contrast, late-onset fetal growth restriction and late-onset preeclampsia are characterized by lower sFlt-1/PlGF ratios, possibly as a result of a weaker placental component in these conditions.2,7 Regarding the prognosis, there is a positive correlation between the sFlt-1/PlGF ratio and the likelihood of complications.8,9 Nevertheless, the heterogeneity of placental disorders cannot be fully explained by means of a simplistic angiogenic imbalance approach. It is intriguing that although fetal growth restriction further complicates almost half of early-onset preeclampsia cases, only 15% of mothers with early fetal growth restriction
OBSTETRICS & GYNECOLOGY
265
are later diagnosed with preeclampsia. Likewise, the severity of maternal disease is not clearly associated with the coexistence of fetal growth restriction.10 The sFlt-1/PlGF ratio could be of value for understanding these different manifestations of placental disease. In this study, we aim to characterize the sFlt-1/PlGF ratio in early- and late-onset fetal growth restriction, with and without concurrent preeclampsia, and to compare them with preeclampsia without fetal growth restriction and pregnancies in which neither was present.
MATERIALS AND METHODS This case–control study was drawn from data collected at the sites of Hospital Universitario 12 de Octubre (Madrid, Spain) and Charité University Hospital (Berlin, Germany) for a prospective European Multicenter Study evaluating the use of the automated determination of the sFlt-1/PlGF ratio as an aid in diagnosis of preeclampsia between November 2007 and March 2011. The study was approved by the respective local ethics committees and all study participants gave their written informed consent before participation. An identical study protocol was used, as described elsewhere.2 In brief, the original study involved pregnant women at any time of pregnancy from week 10 of gestation onward, who were asked to provide a blood sample at enrollment and, whenever possible, additional samples until delivery. The exclusion criteria for the original study were lack of informed consent, loss to follow-up or unknown pregnancy outcome, multiple pregnancy, antiphospholipid antibody syndrome, systemic lupus erythematosus, any other autoimmune disease, and chronic corticosteroid or nonsteroidal antiinflammatory drugs use, except low dosage aspirin, 150 mg per day or less. Serum samples were stored at 280°C until testing was performed at a single laboratory. Measurements of sFlt-1 and PlGF were performed on the fully automated Elecsys system. Investigators and clinicians were blinded to sFlt-1/PlGF ratios. Data collected were entered by the authors in an identical electronic data collection form. The accuracy of the database was validated by auditing of specific relevant variables. A total of 751 pregnant women (yielding a total of 870 serum samples) fulfilled the criteria for their inclusion in the mentioned original study (Fig. 1). Preeclampsia was defined according to the National High Blood Pressure Education Program Working Group on High Blood Pressure in Pregnancy.11 Hemolysis, elevated liver enzymes and low platelets syndrome (HELLP) was diagnosed following Sibai’s criteria12 and superimposed preeclampsia was
266
Herraiz et al
defined as a preexisting hypertension before 20 weeks of gestation with de novo proteinuria or sudden increase in the magnitude of hypertension or appearance of thrombocytopenia or abnormal transaminases or sudden increase in proteinuria when having proteinuria before 20 weeks of gestation. Patients with preeclampsia, HELLP, or superimposed preeclampsia were combined in the preeclampsia or HELLP group for analysis. Fetal growth restriction was defined as an estimated fetal weight by ultrasonography, using Hadlock’s formula13 in both centers, below the 10th centile plus either with an amniotic fluid index less than the 10th percentile in the absence of premature rupture of membranes or a pathologic flow in the umbilical artery with a pulsatility index greater than the 95th percentile.14 Birth weight was converted into a percentile after correction for gestational age at delivery and sex of the newborn, according to local charts.15,16 All cases of fetal growth restriction subsequently were found to have a birth weight less than the 10th centile (small for gestational age [SGA]) and to lack genetic and infection-related conditions that might account for the SGA birth weight. A normal pregnancy outcome (healthy control) was defined as a live-born delivery at 37 weeks of gestation or greater in the absence of any form of hypertensive disorder of pregnancy and without an SGA newborn. After exclusion of samples obtained postpartum (n53) or before 24+0 weeks of gestation (n512), cases with incomplete information (n515), fetuses with congenital anomalies (n511), preterm deliveries (n5103), chronic hypertension (n557), gestational hypertension (n520), and SGA newborns without fetal growth restriction criteria (n542), we had 27 cases of fetal growth restriction and 144 cases of preeclampsia or HELLP with or without fetal growth restriction. Final pregnancy outcome was determined by two senior obstetricians (I.H. and S.V.) and agreement was reached by discussion if necessary. We analyzed two periods according to the gestational age at diagnosis: 24+0 to 33+6 weeks of gestation (early phase) and 34+0 weeks of gestation or greater (late phase). In cases of fetal growth restriction or preeclampsia or HELLP, the sample obtained after diagnosis was used for allocation to the respective gestational age window and analysis. In cases of fetal growth restriction and preeclampsia or HELLP in which fetal growth restriction was diagnosed first, the sample collected after the diagnosis of preeclampsia or HELLP was used. For repeated samples, the sample closest to diagnosis was selected for analysis. Each patient with fetal growth restriction, preeclampsia or HELLP, or fetal growth restriction and
sFlt-1 and PlGF in Growth-Restricted Fetuses
OBSTETRICS & GYNECOLOGY
Total included (singleton pregnancies) (n=751) [870] Postpartum samples: (n=3) [3] Samples collected
Characterization of the Soluble fms-Like Tyrosine Kinase-1 to Placental Growth Factor Ratio in Pregnancies Complicated by Fetal Growth Restriction Ignacio Herraiz, MD, Lisa Antonia Dröge, MD, Enery Gómez-Montes, Alberto Galindo, MD, and Stefan Verlohren, MD
MD,
Wolfgang Henrich,
MD,
OBJECTIVE: To characterize the values of the soluble fms-like tyrosine kinase-1 (sFlt-1) to placental growth factor (PlGF) ratio in pregnancies with fetal growth restriction with or without concurrent preeclampsia or hemolysis, elevated liver enzymes and low platelets syndrome (HELLP) and in pregnancies with normally grown fetuses with or without concurrent preeclampsia or HELLP.
P,.001) and at or after 34 weeks of gestation (117, 66, 165, and 11, respectively, P,.001). The differences among the case subgroups were not statistically different.
METHODS: This is a case–control study performed in two centers (Berlin and Madrid) consisting of 171 singleton pregnancies complicated by fetal growth restriction (n527), preeclampsia or HELLP (n5105) or preeclampsia or HELLP and fetal growth restriction (n539) pairwise matched by gestational age with 171 healthy control pregnancies. Automated measurement of sFlt-1 and PlGF in maternal serum samples was performed after diagnosis (cases) and in gestational-age matched healthy control samples. Samples were analyzed for two timeframes: before and at or after 34 weeks of gestation.
LEVEL OF EVIDENCE: II
RESULTS: Pregnancies with fetal growth restriction, preeclampsia or HELLP, and preeclampsia or HELLP and fetal growth restriction showed higher median values of sFlt1/PlGF ratio than control pregnancies both before 34 weeks of gestation (90, 231, 514, and 3, respectively, From the Fetal Medicine Unit-SAMID, Department of Obstetrics and Gynaecology, Hospital Universitario 12 de Octubre, Madrid, Spain; and the Department of Obstetrics, Charité University Medicine, Berlin, Germany. Corresponding author: Stefan Verlohren, MD, Department of Obstetrics, Charité University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany; e-mail: [email protected]. Financial Disclosure Dr. Verlohren has received lecture fees, consultancy payments, or both from Roche Diagnostics, ThermoFisherScientific, and Novartis. The other authors did not report any potential conflicts of interest. © 2014 by The American College of Obstetricians and Gynecologists. Published by Lippincott Williams & Wilkins. ISSN: 0029-7844/14
VOL. 124, NO. 2, PART 1, AUGUST 2014
CONCLUSION: Fetal growth restriction is characterized by elevated maternal sFlt-1/PlGF ratio, reaching values as high as those observed in preeclampsia or HELLP. (Obstet Gynecol 2014;124:265–73) DOI: 10.1097/AOG.0000000000000367
A
ngiogenic imbalance has emerged as an essential piece to understand the complex puzzle of placental related disorders, which includes fetal growth restriction and preeclampsia. A failure in trophoblast invasion leads to an altered placental production and systemic release of antiangiogenic factors such as soluble fms-like tyrosine kinase-1 (sFlt-1) and proangiogenic factors such as placental growth factor (PlGF).1 There is evidence that angiogenic imbalance, expressed by an increased sFlt-1/PlGF ratio, is present in early-onset fetal growth restriction and in early-onset preeclampsia2–4 supporting that both represent two similar pathophysiologic states.5,6 In contrast, late-onset fetal growth restriction and late-onset preeclampsia are characterized by lower sFlt-1/PlGF ratios, possibly as a result of a weaker placental component in these conditions.2,7 Regarding the prognosis, there is a positive correlation between the sFlt-1/PlGF ratio and the likelihood of complications.8,9 Nevertheless, the heterogeneity of placental disorders cannot be fully explained by means of a simplistic angiogenic imbalance approach. It is intriguing that although fetal growth restriction further complicates almost half of early-onset preeclampsia cases, only 15% of mothers with early fetal growth restriction
OBSTETRICS & GYNECOLOGY
265
are later diagnosed with preeclampsia. Likewise, the severity of maternal disease is not clearly associated with the coexistence of fetal growth restriction.10 The sFlt-1/PlGF ratio could be of value for understanding these different manifestations of placental disease. In this study, we aim to characterize the sFlt-1/PlGF ratio in early- and late-onset fetal growth restriction, with and without concurrent preeclampsia, and to compare them with preeclampsia without fetal growth restriction and pregnancies in which neither was present.
MATERIALS AND METHODS This case–control study was drawn from data collected at the sites of Hospital Universitario 12 de Octubre (Madrid, Spain) and Charité University Hospital (Berlin, Germany) for a prospective European Multicenter Study evaluating the use of the automated determination of the sFlt-1/PlGF ratio as an aid in diagnosis of preeclampsia between November 2007 and March 2011. The study was approved by the respective local ethics committees and all study participants gave their written informed consent before participation. An identical study protocol was used, as described elsewhere.2 In brief, the original study involved pregnant women at any time of pregnancy from week 10 of gestation onward, who were asked to provide a blood sample at enrollment and, whenever possible, additional samples until delivery. The exclusion criteria for the original study were lack of informed consent, loss to follow-up or unknown pregnancy outcome, multiple pregnancy, antiphospholipid antibody syndrome, systemic lupus erythematosus, any other autoimmune disease, and chronic corticosteroid or nonsteroidal antiinflammatory drugs use, except low dosage aspirin, 150 mg per day or less. Serum samples were stored at 280°C until testing was performed at a single laboratory. Measurements of sFlt-1 and PlGF were performed on the fully automated Elecsys system. Investigators and clinicians were blinded to sFlt-1/PlGF ratios. Data collected were entered by the authors in an identical electronic data collection form. The accuracy of the database was validated by auditing of specific relevant variables. A total of 751 pregnant women (yielding a total of 870 serum samples) fulfilled the criteria for their inclusion in the mentioned original study (Fig. 1). Preeclampsia was defined according to the National High Blood Pressure Education Program Working Group on High Blood Pressure in Pregnancy.11 Hemolysis, elevated liver enzymes and low platelets syndrome (HELLP) was diagnosed following Sibai’s criteria12 and superimposed preeclampsia was
266
Herraiz et al
defined as a preexisting hypertension before 20 weeks of gestation with de novo proteinuria or sudden increase in the magnitude of hypertension or appearance of thrombocytopenia or abnormal transaminases or sudden increase in proteinuria when having proteinuria before 20 weeks of gestation. Patients with preeclampsia, HELLP, or superimposed preeclampsia were combined in the preeclampsia or HELLP group for analysis. Fetal growth restriction was defined as an estimated fetal weight by ultrasonography, using Hadlock’s formula13 in both centers, below the 10th centile plus either with an amniotic fluid index less than the 10th percentile in the absence of premature rupture of membranes or a pathologic flow in the umbilical artery with a pulsatility index greater than the 95th percentile.14 Birth weight was converted into a percentile after correction for gestational age at delivery and sex of the newborn, according to local charts.15,16 All cases of fetal growth restriction subsequently were found to have a birth weight less than the 10th centile (small for gestational age [SGA]) and to lack genetic and infection-related conditions that might account for the SGA birth weight. A normal pregnancy outcome (healthy control) was defined as a live-born delivery at 37 weeks of gestation or greater in the absence of any form of hypertensive disorder of pregnancy and without an SGA newborn. After exclusion of samples obtained postpartum (n53) or before 24+0 weeks of gestation (n512), cases with incomplete information (n515), fetuses with congenital anomalies (n511), preterm deliveries (n5103), chronic hypertension (n557), gestational hypertension (n520), and SGA newborns without fetal growth restriction criteria (n542), we had 27 cases of fetal growth restriction and 144 cases of preeclampsia or HELLP with or without fetal growth restriction. Final pregnancy outcome was determined by two senior obstetricians (I.H. and S.V.) and agreement was reached by discussion if necessary. We analyzed two periods according to the gestational age at diagnosis: 24+0 to 33+6 weeks of gestation (early phase) and 34+0 weeks of gestation or greater (late phase). In cases of fetal growth restriction or preeclampsia or HELLP, the sample obtained after diagnosis was used for allocation to the respective gestational age window and analysis. In cases of fetal growth restriction and preeclampsia or HELLP in which fetal growth restriction was diagnosed first, the sample collected after the diagnosis of preeclampsia or HELLP was used. For repeated samples, the sample closest to diagnosis was selected for analysis. Each patient with fetal growth restriction, preeclampsia or HELLP, or fetal growth restriction and
sFlt-1 and PlGF in Growth-Restricted Fetuses
OBSTETRICS & GYNECOLOGY
Total included (singleton pregnancies) (n=751) [870] Postpartum samples: (n=3) [3] Samples collected
