A new model to predict poor maternal outcomes in pre-eclampsia

December 23, 2010

A new model to predict adverse maternal outcomes in pre-eclampsia is discussed in an Article published Online First by The Lancet. The model is built on six variables that researchers identified as critical for predicting the likelihood of a poor outcome for pregnant women admitted to hospital with pre-eclampsia. The Article is by Dr Peter von Dadelszen, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada, and colleagues.

Pre-eclampsia is a condition that can arise in, and is exclusively caused by, pregnancy and usually manifests as raised blood pressure of a pregnant woman together with increased protein in her urine. It is also a state of exaggerated systemic inflammation and remains a leading direct cause of maternal death and disease worldwide, including in high-income countries. Deaths usually result from eclampsia (seizures and coma), uncontrolled hypertension, or systemic inflammation. The only cure for pre-eclampsia is to deliver the baby.

The authors of this new work developed and validated a model called fullPIERS with the aim of identifying the risk of fatal or life-threatening complications for women with pre-eclampsia within 48 h of hospital admission for the disorder. This project was conducted in eight centres in Canada, New Zealand, Australia, and the United Kingdom between September 1, 2003 and January 31, 2010.

The researchers analysed 34 candidate predictor variables that were predictive, available, measurable, frequent, and reliable. These included the mother's demographic characteristics; her past medical history; present symptoms; cardiovascular signs; results of kidney, blood, and liver tests; and fetal assessment tests such as fetal heart rate and estimated weight.

The researchers assessed the fullPIERS model once 200 women were entered into the study database and then monthly thereafter, which allowed the team to abandon variables that weren't statistically informative. Of the 2023 women with pre-eclampsia who were included in the study, 261 (13 per cent) had adverse outcomes. None died.

The researchers used statistical analysis to identify the variables that predicted poor outcomes in women with pre-eclampsia and built the fullPIERS model on these variables: gestational age, chest pain, shortness of breath, liver enzyme test (aspartate aminotransferase test), platelet counts, kidney function test (serum creatinine levels) and blood oxygen levels.

The authors say: "Abandoning of redundant tests seems reasonable. For example, the testing of liver enzymes aspartate transaminase, alanine transaminase, and lactate dehydrogenase might be replaced by aspartate transaminase alone without the loss of important information and with reduced laboratory costs."

Results showed that the fullPIERS model predicted adverse maternal outcomes within 48 hours of eligibility and the model also performed well for predicting adverse maternal outcomes up to seven days after eligibility. These time periods are clinically important as the first 48 hours allows clinicians to administer steroids to prepare the baby for preterm delivery and plan for inducing labour if required.

The authors say: "The fullPIERS model identifies women at increased risk of adverse outcomes up to 7 days before complications arise and can thereby modify direct patient care (eg, timing of delivery, place of care), improve the design of clinical trials, and inform biomedical investigations related to pre-eclampsia."

The fullPIERS model accurately places women into risk categories (see table 4 full paper). This will enable clinicians, women, and their families to more accurately estimate maternal risk when making decisions about the timing and mode of delivery. The authors add: "An important effect of fullPIERS might be identification of women at lowest risk of adverse outcomes, who can be offered expectant management either remote from term for perinatal benefit or at or near term during induction of labour."

The authors also believe the model will also help doctors better understand the progression of pre-eclampsia.

In a linked Comment, Dr Gary L Darmstadt, Bill and Melinda Gates Foundation, Family Health Division, Global Health Program, Seattle, WA, USA, and colleagues say: "Hypertension in pregnancy and pre-eclampsia challenge the public-health community because of the need to simultaneously protect the mother and baby and to balance sometimes competing needs to accelerate or delay the end of the pregnancy. This study focuses primarily on maternal outcomes but also has implications for neonatal health. Hypertension in pregnancy and pre-eclampsia are conditions that call for further collaboration between maternal and neonatal health experts."

They conclude: "We applaud von Dadelszen and colleagues in their efforts to validate the fullPIERS model and thereby advance future treatments and interventions. We hope that this new knowledge will be translated into effective and immediate action and further adapted and validated for use in low-income and middle-income countries, and thus used to its greatest advantage to save the lives of mothers and babies."
Dr Peter von Dadelszen, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada. T) 1-604-875-2401 E) pvd@cw.bc.ca

Dr Gary L Darmstadt, Bill and Melinda Gates Foundation, Family Health Division, Global Health Program, Seattle, WA, USA. T) +1 206-225-0482 E) gary.darmstadt@gatesfoundation.org

For full Article and Comment, see: http://press.thelancet.com/preeclampsia.pdf




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