Early warning system hypertension thresholds to predict adverse outcomes in pre-eclampsia: A prospective cohort study.

Hannah L Nathan,Andrew H Shennan,John Anthony,Wilhelm Steyn,Lucy C Chappell,David R Hall,Elodie Lawley,Paul T Seed,Annemarie De Greeff,Natasha L Hezelgrave

doi:10.1016/j.preghy.2017.11.003

Abstract

To evaluate the association between blood pressure (BP) measurements and adverse outcomes in women with pre-eclampsia. A prospective cohort study of women with pre-eclampsia admitted to three South African tertiary facilities. BP was measured using the CRADLE Vital Signs Alert (VSA), incorporated with a traffic light early warning system; green: systolic BP <140 mmHg and diastolic BP <90 mmHg, yellow: systolic BP 140-159 and/or diastolic BP 90-109 mmHg (but neither is above the upper threshold), red: systolic BP ≥160 mmHg and/or diastolic BP ≥110 mmHg. Maternal: death, eclampsia, stroke, kidney injury; process measures: magnesium sulfate use, Critical Care Unit (CCU) admission; perinatal: stillbirth, neonatal death, preterm delivery. Of 1547 women with pre-eclampsia (including 42 twin pregnancies), 33.0% of women triggered a red light on admission and 78.6% at their highest BP. Severe hypertension and adverse outcomes were common across yellow and red categories. Comparing admission red to yellow lights, there was a significant increase in kidney injury (OR 1.74, CI 1.31-2.33, trend test p = .003), magnesium sulfate use (OR 3.40, CI 2.24-5.18, p < .001) and CCU admission (OR 1.50, CI 1.18-1.91, p < .001), but not for maternal death, eclampsia, extended perinatal death or preterm delivery. The CRADLE VSA, with integrated traffic light early warning system, can identify women who are hypertensive, at increased risk of severe pre-eclampsia complications and in need of escalation of care. Women who triggered a red light were at increased risk of kidney injury, magnesium sulfate use and CCU admission.

Highlights

Pre-eclampsia affects 3-5% of pregnancies and is a leading cause of maternal and perinatal mortality and severe morbidity globally.[1, 2] In high-income countries, maternal mortality from pre-eclampsia is rare; this is a result of prompt action following diagnosis facilitated by blood pressure (BP) and urinary dipstick proteinuria measurement.[3]
Participant characteristics and BP results are shown in Table 1. 511 (33.0%) women triggered a red light as their ‘admission’ BP and 1216 (78.6%) women triggered a red light at their ‘highest’ BP; nine (0.6%) women did not trigger a yellow or red light as an inpatient i.e. their BP remained within normal limits
Statement of principal findings The risk of maternal death, eclampsia, and perinatal death was similar across the women who triggered a yellow or red light on the CRADLE Vital Signs Alert (VSA)

Summary

Introduction

Pre-eclampsia affects 3-5% of pregnancies and is a leading cause of maternal and perinatal mortality and severe morbidity globally.[1, 2] In high-income countries, maternal mortality from pre-eclampsia is rare; this is a result of prompt action following diagnosis facilitated by blood pressure (BP) and urinary dipstick proteinuria measurement.[3]. The CRADLE Vital Signs Alert (VSA) is a hand-held, upper-arm, semi-automated device measuring BP and pulse to facilitate prompt recognition of abnormalities in vital signs. It has been designed for healthcare providers from LMICs and meets the World Health Organisation’s requirements for use in low-resource settings.[5] Device accuracy has been validated for use in pregnancy, including pre-eclampsia and low BP in pregnancy.[6,7,8] The device incorporates a traffic light early warning system, aimed at alerting all healthcare providers (regardless of training) to vital sign abnormalities secondary to pre-eclampsia, maternal haemorrhage and sepsis.

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