The US Preventive Services Task Force (USPSTF) recommends screening for pre-eclampsia in pregnant women with blood pressure measurements throughout pregnancy. This is a B recommendation, which in this case indicates that there is moderate certainty that the net benefit is substantial.
Preeclampsia is defined as new-onset hypertension (or, in patients with existing hypertension, worsening hypertension) occurring after 20 weeks of gestation, combined with either new-onset proteinuria (excess protein in the urine) or other signs or symptoms involving multiple organ systems. It is a relatively common hypertensive disorder occurring during pregnancy, affecting approximately 4% of pregnancies in the US. Preeclampsia can lead to poor health outcomes in both the mother and infant. It is the leading cause of preterm delivery and low birth weight in the US and may also lead to other serious maternal complications.
To update its 1996 recommendation, the USPSTF reviewed the evidence on the accuracy of screening and diagnostic tests for preeclampsia, the potential benefits and harms of screening for preeclampsia, the effectiveness of risk prediction tools, and the benefits and harms of treatment of screen-detected preeclampsia.
The USPSTF is an independent, volunteer panel of experts that makes recommendations about the effectiveness of specific preventive care services such as screenings, counselling services, and preventive medications.
Detection
Obtaining blood pressure measurements to screen for preeclampsia could allow for early identification and diagnosis of the condition, resulting in close surveillance and effective treatment to prevent serious complications. The USPSTF has previously established that there is adequate evidence on the accuracy of blood pressure measurements to screen for preeclampsia. The USPSTF found adequate evidence that testing for protein in the urine with a dipstick test has low diagnostic accuracy for detecting proteinuria in pregnancy.
Benefits of Early Detection and Treatment
Preeclampsia is a complex syndrome. It can quickly evolve into a severe disease that can result in serious, even fatal health outcomes for the mother and infant. The ability to screen for preeclampsia using blood pressure measurements is important to identify and effectively treat this potentially unpredictable and fatal condition. The USPSTF found adequate evidence that the well-established treatments of preeclampsia result in a substantial benefit for the mother and infant by reducing maternal and perinatal morbidity and mortality. The USPSTF found inadequate evidence on the effectiveness of risk prediction tools (clinical indicators, serum markers) that would support different screening strategies for predicting preeclampsia.
Harms of Early Detection and Treatment
The USPSTF found adequate evidence to bound the potential harms of screening for and treatment of preeclampsia as no greater than small. This assessment was based on the known harms of treatment with antihypertension medications, induced labour, and magnesium sulfate; the likely few harms from screening with blood pressure measurements; and the potential poor maternal and perinatal outcomes resulting from severe untreated preeclampsia and eclampsia. The USPSTF found inadequate evidence on the harms of risk prediction.
Summary
The USPSTF concludes with moderate certainty that screening for preeclampsia in pregnant women with blood pressure measurements has a substantial net benefit.
Abstract 1
Importance: Preeclampsia affects approximately 4% of pregnancies in the United States. It is the second leading cause of maternal mortality worldwide and may lead to serious maternal complications, including stroke, eclampsia, and organ failure. Adverse perinatal outcomes for the fetus and newborn include intrauterine growth restriction, low birth weight, and stillbirth. Many of the complications associated with preeclampsia lead to early induction of labor or cesarean delivery and subsequent preterm birth.
Subpopulation considerations: Preeclampsia is more prevalent among African American women than among white women. Differences in prevalence may be, in part, due to African American women being disproportionally affected by risk factors for preeclampsia. African American women also have case fatality rates related to preeclampsia 3 times higher than rates among white women. Inequalities in access to adequate prenatal care may contribute to poor outcomes associated with preeclampsia in African American women.
Objective: To update the 1996 US Preventive Services Task Force (USPSTF) recommendation on screening for preeclampsia.
Evidence review: The USPSTF reviewed the evidence on the accuracy of screening and diagnostic tests for preeclampsia, the potential benefits and harms of screening for preeclampsia, the effectiveness of risk prediction tools, and the benefits and harms of treatment of screen-detected preeclampsia.
Findings: Given the evidence that treatment can reduce maternal and perinatal morbidity and mortality, and the well-established accuracy of blood pressure measurements, the USPSTF found adequate evidence that screening for preeclampsia results in a substantial benefit for the mother and infant. In addition, there is adequate evidence to bound the harms of screening for and treatment of preeclampsia as no greater than small. Therefore, the USPSTF concludes with moderate certainty that there is a substantial net benefit of screening for preeclampsia in pregnant women.
Conclusions and Recommendation: The USPSTF recommends screening for preeclampsia in pregnant women with blood pressure measurements throughout pregnancy. (B recommendation)
Authors
US Preventive Services Task Force
Abstract 2
Importance: Preeclampsia is a complex disease of pregnancy with sometimes serious effects on maternal and infant morbidity and mortality. It is defined by hypertension after 20 weeks’ gestation and proteinuria or other evidence of multisystem involvement.
Objective: To systematically review the benefits and harms of preeclampsia screening and risk assessment for the US Preventive Services Task Force.
Data Sources: MEDLINE, PubMed, and Cochrane Central Register of Controlled Trials databases from 1990 through September 1, 2015. Surveillance for new evidence in targeted publications was conducted through October 5, 2016.
Study Selection: English-language trials and observational studies, including externally validated prediction models, of screening effectiveness, benefits, and harms from routine preeclampsia screening during pregnancy.
Data Extraction and Synthesis: Independent dual review of article abstracts and full texts against a priori inclusion criteria. Meta-analysis was not performed because of clinical and statistical heterogeneity of included studies.
Main Outcomes and Measures: Maternal and infant health outcomes, including eclampsia, stroke, stillbirth, preterm birth, and low birth weight; screening and risk prediction test performance; harms of screening and risk assessment.
Results: Twenty-one studies (13 982 participants) were included. No studies directly compared the effectiveness of preeclampsia screening in a screened population vs an unscreened population; 1 US trial (n = 2764) found no difference in benefits or harms with fewer prenatal visits but was underpowered for rare, serious outcomes. For harms, a before-after comparison cohort noninferiority study of urine protein screening for specific indications compared with routine screening (n = 1952) did not identify harms with fewer urine screening tests. Four studies (n = 7123) reported external validation performance of 16 risk prediction models, 5 of which had good or better discrimination (c statistic >0.80) for prediction of preeclampsia, and positive predictive values of 4% in the largest, most applicable validation cohorts. Calibration was not reported despite being a key model performance measure. There were no studies of urine screening test performance conducted in asymptomatic primary care populations; 14 studies of protein urine test performance among women being evaluated for suspected preeclampsia (n = 1888) had wide-ranging test accuracy (sensitivity, 22%-100%; specificity, 36%-100%) and high statistical and clinical heterogeneity in tests used, eligibility criteria, and proteinuria prevalence (8.7%-93.8%).
Conclusions and Relevance: Evidence to estimate benefits and harms of preeclampsia screening and the test performance of different screening approaches over the course of pregnancy was limited. Externally validated risk prediction models had limited applicability and lacked calibration and clinical implementation data needed to support routine use. Further research is needed to better inform risk-based screening approaches and improve screening strategies, given the complex pathophysiology and clinical unpredictability of preeclampsia.
Authors
Jillian T Henderson; Jamie H Thompson; Brittany U Burda; Amy Cantor
[link url="http://media.jamanetwork.com/news-item/screening-for-preeclampsia-in-pregnant-women-recommended/"]JAMA material[/link]
[link url="http://jamanetwork.com/journals/jama/fullarticle/2620095"]JAMA abstract 1[/link]
[link url="http://jamanetwork.com/journals/jama/fullarticle/2620094"]JAMA abstract 2[/link]