Methods
Pregnant women with HELLP syndrome with or without preeclampsia as well
as features of AFLP at our referral institution between 2011 and 2018
were prospectively enrolled. At admission serum levels of sFlt-1 and
PLGF were measured using electro-chemiluminescence immunoassays
(ELECSYS; Roche Diagnostics GmbH, Mannheim, Germany) on Cobas e 601
analyzer (Hitachi High Technology Co, Tokyo, Japan). Dilutional series
were performed using human serum in a ratio of 1:10 in patients with
sFlt-1 values beyond the detection limit of 85.0 ng/ml. Clinical and
obstetrical data were retrieved from patient charts.
HELLP syndrome was defined according to Tennessee and Mississippi
classification as lactate dehydrogenase (LDH) ≥600U/l as a surrogate
marker of haemolysis, alanine and aspartate transaminase (ALT/AST)
≥70U/l for elevated liver enzymes. We included only patients having
platelets count of less than 100G/l according to the statment of ISSHP
and the guideline of the German Society of Gynecology and
Obstetrics18, 19. Hence, class 3 of the Mississippi
classification (platelet 100 to 150 G/L) was not taken into account, as
it is considered more as a transient form of HELLP
syndrome.18
Preeclampsia was defined, according to the revised statement of the
international society for the study of hypertension in pregnancy (ISSHP)
2014, as chronic or gestational hypertension (blood pressure ≥140/90mmHg
in at least two measurements) accompanied by significant proteinuria
(≥300mg/24h) or signs of utero-placental dysfunction with fetal growth
restriction (FGR) or maternal endothelial
dysfunction.3 According to this ISSHP statement,
patients were considered suffering from a severe preeclampsia when
showing severe hypertension (≥160/110mmHg), signs of impending eclampsia
(headache, visual disturbances) or when diagnosed with HELLP syndrome.
Fetal growth restriction (FGR) was defined as fetal abdominal
circumference <5th percentile or estimated fetal weight
<10th percentile for gestational age with altered fetal and/or
maternal hemodynamic or an abnormal growth trajectory over
time.20, 21
We used the Swansea criteria as a diagnostic tool for AFLP. Patients
were considered being positive if at least 6 criteria were
present.5 To correct for gestational age-dependent
angiogenic profile pattern, the time points of blood draw were matched
(± 1 week) and each AFLP case was matched with two patients with HELLP
syndrome with and without preeclampsia.
Statistical analysis was performed with GraphPad Prism version 8.0 for
Windows (GraphPad Software, San Diego, CA, USA). Continuous variables
were analysed using parametric and nonparametric tests. Proportions were
analysed using Chi2-test or Fischer’s exact test where
appropriate. Correlations between numerical parameters were analysed
using the Spearman’s rho bivariate correlation test. A receiver
operating characteristic (ROC) curve analysis was used to describe the
relationship between sensitivity and false-positive rate for different
angiogenic values to predict AFLP. A p-value of <0.05 was
considered for significancy. The study was approved by the institutional
ethics committee of the canton of Bern (Kantonale Ethikkommission Bern,
Ref.-Nr.: 365/15).