PREPARE: protocol for a stepped wedge trial to evaluate whether a risk stratification model can reduce preterm deliveries among women with suspected or confirmed preterm pre-eclampsia

Hypertension in Pregnancy and Preeclampsia: Variation in Clinical Management Strategies Among Obstetric/Gynecologic Provider Type

Background

Preeclampsia, a condition in pregnancy characterized by new onset high blood pressure and proteinuria, complicates 2%-8% of pregnancies globally. Early detection, careful monitoring, and treatment of high blood pressure are crucial in preventing mortality related to preeclampsia disorders. There is limited data that examines obstetric/gynecologic (OBGYN) provider-type practices concerning management of hypertensive disorders of pregnancy to reduce early onset preeclampsia (EOP). We assessed the knowledge and practice patterns of OBGYN management to reduce EOP.

Methods

We conducted a semistructured survey with OBGYN residents, maternal-fetal medicine fellows, and attending physicians (OBGYN and family medicine) at a single academic medical center to assess the management of hypertensive disorders to EOP.

Results

Thirty-one participants (71% residents/fellows 29% attendings) completed the survey. Seventy-eight percent of attendings indicated they discuss blood pressure and preeclampsia with all patients compared to 50% of residents/fellows (p = 0.31). Eighty-nine percent of attendings reported they are extremely likely to monitor high-risk patients compared to 36% of residents/fellows (p = 0.07).

Conclusion

Attending physicians were more likely to appropriately manage hypertension in women at risk for pregnancy compared to residents/fellows. Further research is needed on monitoring high-risk patients.

PREPARE: A Stepped-Wedge Cluster-Randomized Trial to Evaluate Whether Risk Stratification Can Reduce Preterm Deliveries Among Patients With Suspected or Confirmed Preterm Preeclampsia

BACKGROUND

Early delivery in preterm preeclampsia may reduce the risks for the patient, but consequences of prematurity may be substantial for the baby. This trial evaluated whether the implementation of a risk stratification model could safely reduce prematurity.

METHODS

This was a stepped-wedge cluster-randomized trial in seven clusters. Patients presenting with suspected or confirmed preeclampsia between 20+0 and 36+6 gestational weeks were considered eligible. At the start of the trial, all centers were allocated in the preintervention phase, and patients enrolled in this phase were managed according to local treatment guidance. Subsequently, every 4 months, 1 randomly allocated cluster transitioned to the intervention. Patients enrolled in the intervention phase had sFlt-1 (soluble fms-like tyrosine kinase-1)/PlGF (placental growth factor) ratio and preeclampsia integrated estimate of risk assessments performed. If sFlt-1/PlGF ≤38 and preeclampsia integrated estimate of risk <10%, patients were considered low risk and clinicians received recommendations to defer delivery. If sFlt-1/PlGF >38 and preeclampsia integrated estimate of risk ≥10%, patients were considered not low risk, and clinicians received recommendations to increase surveillance. The primary outcome was the proportion of patients with preterm preeclampsia delivered prematurely out of total deliveries.

RESULTS

Between March 25, 2017 and December 24, 2019, 586 and 563 patients were analyzed in the intervention and usual care groups, respectively. The event rate was 1.09% in the intervention group, and 1.37% in the usual care group. After prespecified adjustments for variation between and within clusters over time, the adjusted risk ratio was 1.45 ([95% CI, 1.04-2.02]; P=0.029), indicating a higher risk of preterm deliveries in the intervention group. Post hoc analysis including calculation of risk differences did not show evidence of statistical differences. Abnormal sFlt-1/PlGF was associated with a higher rate of identifying preeclampsia with severe features.

CONCLUSIONS

The introduction of an intervention based on biomarkers and clinical factors for risk stratification did not lead to reductions in preterm deliveries. Further training on the interpretation of disease severity in preeclampsia and the development of additional risk stratification is needed before adoption into clinical practice.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03073317.

Response adaptive intervention allocation in stepped-wedge cluster randomized trials

BACKGROUND

Stepped-wedge cluster randomized trial (SW-CRT) designs are often used when there is a desire to provide an intervention to all enrolled clusters, because of a belief that it will be effective. However, given there should be equipoise at trial commencement, there has been discussion around whether a pre-trial decision to provide the intervention to all clusters is appropriate. In pharmaceutical drug development, a solution to a similar desire to provide more patients with an effective treatment is to use a response adaptive (RA) design.

METHODS

We introduce a way in which RA design could be incorporated in an SW-CRT, permitting modification of the intervention allocation during the trial. The proposed framework explicitly permits a balance to be sought between power and patient benefit considerations. A simulation study evaluates the methodology.

RESULTS

In one scenario, for one particular RA design, the proportion of cluster-periods spent in the intervention condition was observed to increase from 32.2% to 67.9% as the intervention effect was increased. A cost of this was a 6.2% power drop compared to a design that maximized power by fixing the proportion of time in the intervention condition at 45.0%, regardless of the intervention effect.

CONCLUSIONS

An RA approach may be most applicable to settings for which the intervention has substantial individual or societal benefit considerations, potentially in combination with notable safety concerns. In such a setting, the proposed methodology may routinely provide the desired adaptability of the roll-out speed, with only a small cost to the study's power.

Placental growth factor measurements in the assessment of women with suspected Preeclampsia: A stratified analysis of the PARROT trial

OBJECTIVE

Placental growth factor testing decreases time to recognition of preeclampsia and may reduce severe maternal adverse outcomes. This analysis aims to describe the clinical phenotype of women by PlGF concentration, and to determine the mechanism(s) underpinning the reduction in severe maternal adverse outcomes in the PARROT trial, in order to inform how PlGF testing may be optimally used within clinical management algorithms.

STUDY DESIGN

This was a planned secondary analysis from the PARROT trial that compared revealed PlGF testing and management guidance with usual care in the assessment of women with suspected preterm preeclampsia.

MAIN OUTCOME MEASURES

Maternal and perinatal outcomes following stratification of women by trial group, and measured PlGF concentration.

RESULTS

1006 women were included. PlGF < 100 pg/ml identified women with more marked hypertension, increased adverse maternal outcomes and preterm delivery rates, and higher rates of small for gestational age infants. There was a reduction in adverse maternal outcomes in women whose results were revealed when PlGF levels were 12-100 pg/ml compared to usual care (3.8% vs 6.9%; aOR 0.15(95% CI 0.03-0.92). There was no significant difference in gestation at delivery between concealed or revealed groups in any PlGF categories.

CONCLUSION

Low PlGF concentrations are associated with severe preeclampsia. The reduction in severe adverse maternal outcomes may be mediated through quicker diagnosis and intensive surveillance, as recommended by the management algorithm for those at increased risk. PlGF is particularly beneficial in those who test 12-100 pg/ml, as these may be women with silent multi-organ disease who otherwise may go undetected.