Aspirin for pre-eclampsia: beware of subgroup meta-analysis

Clinical analysis of diabetes in pregnancy with stillbirth

We analyzed the clinical characteristics of patients with diabetes in pregnancy (DIP) associated with stillbirth and explored strategies to reduce its incidence. We retrospectively analyzed 71 stillbirths associated with DIP (group A) and 150 normal pregnancies (group B) during 2009 to 2018. The incidence of the following was higher in group A (P < .05): hypertensive disorders (38.03% vs 6.00%), placenta previa (14.08% vs 2.67%), placental abruption (5.63% vs 0.67%), fetal malformation (8.45% vs 0.67%), fasting plasma glucose (FPG) ≥ 7.0 mmol/L (46.48% vs 0.67%), 2-h postprandial plasma glucose ≥ 11.1 mmol/L (57.75% vs 6.00%), HbA1c ≥ 6.5% (63.38% vs 6.00%), and polyhydramnios (11.27% vs 4.67). The incidence of oligohydramnios (4.23% vs 6.67%) was lower in group A than in group B (P < .05). According to the gestational age at the time of stillbirth, Group-A cases were subgrouped into miscarriages (20-27+6 weeks), premature deliveries (28-36+6 weeks), and full-term deliveries (≥37 weeks). Age, parity, and DIP type did not differ among the subgroups (P > .05). Among patients with DIP, antenatal FPG, 2-h postprandial plasma glucose, and HbA1c were significantly associated with stillbirth (P < .05). Stillbirth was first detected at 22 weeks and typically occurred at 28-36+6 weeks. DIP was associated with a higher incidence of stillbirth, and FPG, 2-h postprandial plasma glucose, and HbA1c were potential indicators of stillbirth in DIP. Age (odds ratio [OR]: 2.21, 95% confidence interval [CI]: 1.67-2.74), gestational hypertension (OR: 3.44, 95% CI: 2.21-4.67), body mass index (OR: 2.86, 95% CI: 1.95-3.76), preeclampsia (OR: 2.29, 95% CI: 1.45-3.12), and diabetic ketoacidosis (OR: 3.99, 95% CI: 1.22-6.76) were positively correlated with the occurrence of stillbirth in DIP. Controlling perinatal plasma glucose, accurately detecting and managing comorbidities/complications, and timely termination of pregnancy can reduce the incidence of stillbirths associated with DIP.

Antiplatelet agents for preventing pre-eclampsia and its complications

BACKGROUND

Pre-eclampsia is associated with deficient intravascular production of prostacyclin, a vasodilator, and excessive production of thromboxane, a vasoconstrictor and stimulant of platelet aggregation. These observations led to the hypotheses that antiplatelet agents, low-dose aspirin in particular, might prevent or delay development of pre-eclampsia.

OBJECTIVES

To assess the effectiveness and safety of antiplatelet agents, such as aspirin and dipyridamole, when given to women at risk of developing pre-eclampsia.

SEARCH METHODS

For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (30 March 2018), and reference lists of retrieved studies. We updated the search in September 2019 and added the results to the awaiting classification section of the review.

SELECTION CRITERIA

All randomised trials comparing antiplatelet agents with either placebo or no antiplatelet agent were included. Studies only published in abstract format were eligible for inclusion if sufficient information was available. We would have included cluster-randomised trials in the analyses along with individually-randomised trials, if any had been identified in our search strategy. Quasi-random studies were excluded. Participants were pregnant women at risk of developing pre-eclampsia. Interventions were administration of an antiplatelet agent (such as low-dose aspirin or dipyridamole), comparisons were either placebo or no antiplatelet.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trials for inclusion and extracted data independently. For binary outcomes, we calculated risk ratio (RR) and its 95% confidence interval (CI), on an intention-to-treat basis. For this update we incorporated individual participant data (IPD) from trials with this available, alongside aggregate data (AD) from trials where it was not, in order to enable reliable subgroup analyses and inclusion of two key new outcomes. We assessed risk of bias for included studies and created a 'Summary of findings' table using GRADE.

MAIN RESULTS

Seventy-seven trials (40,249 women, and their babies) were included, although three trials (relating to 233 women) did not contribute data to the meta-analysis. Nine of the trials contributing data were large (> 1000 women recruited), accounting for 80% of women recruited. Although the trials took place in a wide range of countries, all of the nine large trials involved only women in high-income and/or upper middle-income countries. IPD were available for 36 trials (34,514 women), including all but one of the large trials. Low-dose aspirin alone was the intervention in all the large trials, and most trials overall. Dose in the large trials was 50 mg (1 trial, 1106 women), 60 mg (5 trials, 22,322 women), 75mg (1 trial, 3697 women) 100 mg (1 trial, 3294 women) and 150 mg (1 trial, 1776 women). Most studies were either low risk of bias or unclear risk of bias; and the large trials were all low risk of bas. Antiplatelet agents versus placebo/no treatment The use of antiplatelet agents reduced the risk of proteinuric pre-eclampsia by 18% (36,716 women, 60 trials, RR 0.82, 95% CI 0.77 to 0.88; high-quality evidence), number needed to treat for one women to benefit (NNTB) 61 (95% CI 45 to 92). There was a small (9%) reduction in the RR for preterm birth <37 weeks (35,212 women, 47 trials; RR 0.91, 95% CI 0.87 to 0.95, high-quality evidence), NNTB 61 (95% CI 42 to 114), and a 14% reduction infetal deaths, neonatal deaths or death before hospital discharge (35,391 babies, 52 trials; RR 0.85, 95% CI 0.76 to 0.95; high-quality evidence), NNTB 197 (95% CI 115 to 681). Antiplatelet agents slightly reduced the risk of small-for-gestational age babies (35,761 babies, 50 trials; RR 0.84, 95% CI 0.76 to 0.92; high-quality evidence), NNTB 146 (95% CI 90 to 386), and pregnancies with serious adverse outcome (a composite outcome including maternal death, baby death, pre-eclampsia, small-for-gestational age, and preterm birth) (RR 0.90, 95% CI 0.85 to 0.96; 17,382 women; 13 trials, high-quality evidence), NNTB 54 (95% CI 34 to 132). Antiplatelet agents probably slightly increase postpartum haemorrhage > 500 mL (23,769 women, 19 trials; RR 1.06, 95% CI 1.00 to 1.12; moderate-quality evidence due to clinical heterogeneity), and they probably marginally increase the risk of placental abruption, although for this outcome the evidence was downgraded due to a wide confidence interval including the possibility of no effect (30,775 women; 29 trials; RR 1.21, 95% CI 0.95 to 1.54; moderate-quality evidence). Data from two large trials which assessed children at aged 18 months (including results from over 5000 children), did not identify clear differences in development between the two groups.

AUTHORS' CONCLUSIONS

Administering low-dose aspirin to pregnant women led to small-to-moderate benefits, including reductions in pre-eclampsia (16 fewer per 1000 women treated), preterm birth (16 fewer per 1000 treated), the baby being born small-for-gestational age (seven fewer per 1000 treated) and fetal or neonatal death (five fewer per 1000 treated). Overall, administering antiplatelet agents to 1000 women led to 20 fewer pregnancies with serious adverse outcomes. The quality of evidence for all these outcomes was high. Aspirin probably slightly increased the risk of postpartum haemorrhage of more than 500 mL, however, the quality of evidence for this outcome was downgraded to moderate, due to concerns of clinical heterogeneity in measurements of blood loss. Antiplatelet agents probably marginally increase placental abruption, but the quality of the evidence was downgraded to moderate due to low event numbers and thus wide 95% CI. Overall, antiplatelet agents improved outcomes, and at these doses appear to be safe. Identifying women who are most likely to respond to low-dose aspirin would improve targeting of treatment. As almost all the women in this review were recruited to the trials after 12 weeks' gestation, it is unclear whether starting treatment before 12 weeks' would have additional benefits without any increase in adverse effects. While there was some indication that higher doses of aspirin would be more effective, further studies would be warranted to examine this.

Low-dose aspirin at ≤16 weeks of gestation for preventing preeclampsia and its maternal and neonatal adverse outcomes: A systematic review and meta-analysis

The aim of the present meta-analysis study was to evaluate the efficacy of low-dose aspirin, commenced at ≤16 weeks of gestation, in preventing preterm and term preeclampsia, as well as associated maternal and neonatal adverse events in women at risk of preeclampsia. The Embase, PubMed, Cochrane Central Register of Controlled Trials and the Web of Science databases were searched for relevant random controlled trials (RCTs) published between January 1979 and October 2017. After quality assessment and data extraction, a meta-analysis was performed using RevMan 5.3 software. Outcomes of interest were preeclampsia with subgroups of preterm preeclampsia (delivery at <37 weeks) and term preeclampsia, as well as maternal adverse outcomes, including gestational hypertension, postpartum hemorrhage and preterm birth, and neonatal adverse outcomes, including intrauterine growth retardation (IUGR) or small for gestation age infant (SGA), stillbirth or death, and newborn weight. A total of 10 RCTs involving 3,168 participants were included. The meta-analysis demonstrated that, compared with placebo or no treatment, low-dose aspirin was associated with a significant reduction in the overall risk ratio (RR) of preeclampsia regardless of the time to delivery [RR=0.67; 95% confidence interval (CI)=0.57-0.80]. This was apparent for preterm preeclampsia (RR=0.35; 95% CI=0.13-0.94) but not for term preeclampsia (RR=1.01; 95% CI=0.60-1.70). Except for postpartum hemorrhage, low-dose aspirin also significantly reduced the risk of maternal and neonatal adverse outcomes. In conclusion, low-dose aspirin in women at risk of preeclampsia, commenced at ≤16 weeks of gestation, was associated with a reduced risk of preterm preeclampsia, and of adverse maternal and neonatal outcomes.

Aspirin for the prevention of preterm and term preeclampsia: systematic review and metaanalysis

OBJECTIVE DATA

Metaanalyses of randomized controlled trials have reported contradictory results about the effect of aspirin in the prevention of preeclampsia, both in terms of the gestational age at the onset of treatment and the dose of the drug. The controversy may be resolved by a metaanalysis that includes several recently published trials and particularly the large Combined Multimarker Screening and Randomized Patient Treatment with Aspirin for Evidence-based Preeclampsia Prevention trial and by examination of whether there is a difference of the effect of aspirin on preterm vs term preeclampsia.

STUDY

We performed a systematic review and metaanalysis that evaluated the prophylactic effect of aspirin during pregnancy.

STUDY APPRAISAL AND SYNTHESIS METHODS

We completed a literature search through PubMed, Cinhal, Embase, Web of Science, and Cochrane library from 1985 to June 2017. Relative risks with random effect were calculated with their 95% confidence intervals.

RESULTS

Sixteen trials that included 18,907 participants provided data for preterm and term preeclampsia. Eight of the included studies were evaluated as being of good quality, and the other 8 studies were deemed to be of poor or uncertain quality. There was high heterogeneity within studies (I2 >50%) for preterm and term preeclampsia, but no heterogeneity was found in the subgroup of preterm preeclampsia when the onset of treatment was ≤16 weeks of gestation and the daily dose of aspirin was ≥100 mg (I2=0%). Administration of aspirin was associated with reduction in the risk of preterm preeclampsia (relative risk, 0.62; 95% confidence interval, 0.45-0.87), but there was no significant effect on term preeclampsia (relative risk, 0.92; 95% confidence interval, 0.70-1.21). The reduction in preterm preeclampsia was confined to the subgroup in which aspirin was initiated at ≤16 weeks of gestation and at a daily dose of ≥100 mg (relative risk, 0.33; 95% confidence interval, 0.19-0.57). This effect was also observed in the high-quality studies. The reduction in preterm preeclampsia that was observed in the largest trial (Combined Multimarker Screening and Randomized Patient Treatment with Aspirin for Evidence-based Preeclampsia Prevention; n=1620; relative risk, 0.38; 95% confidence interval, 0.20-0.72) was similar to that in the 5 smaller trials in which aspirin was initiated at ≤16 weeks of gestation and at a daily dose of ≥100 mg (n=639; relative risk, 0.22; 95% confidence interval, 0.07-0.66).

CONCLUSION

Aspirin reduces the risk of preterm preeclampsia, but not term preeclampsia, and only when it is initiated at ≤16 weeks of gestation and at a daily dose of ≥100 mg.

Role of Aspirin in High Pulsatility Index of Uterine Artery: A Consort Study

Background

Preeclampsia is a heterogeneous disorder prevalent in 3-10% of pregnant women globally. The etiology is multifactorial. There is a initial stage of endothelial dysfunction and placental ischemia (Stage 1); this leads to maternal syndrome of hypertension, edema, and proteinuria (Stage 2). Drugs acting on immunomodulatory, anti-inflammatory, antioxidant and proresolving pathways can minimize the complications of preeclampsia. The therapeutic effect of aspirin is based on acetyl group and salicylate group. Both components have independent therapeutic effects on anti-inflammatory pathway and proresolving pathway.

Aims and Objectives

This study was designed to assess the effectiveness and safety of aspirin in prevention and treatment of symptoms and complications of preeclampsia in women at high risk of preeclampsia.

Methods

This is a prospective experimental study to evaluate the effectiveness of aspirin versus placebo in the prevention of maternal syndrome of preeclampsia in women with high risk of preeclampsia (G1 = 97, G2 = 92). Patients with age ≥ 34, chronic hypertension, multiple pregnancies, gestational diabetes, and high pulsatility index of uterine artery were enrolled between 12 and 20 weeks of gestation and prescribed 75 mg aspirin daily till 34 weeks of gestation. Control group was not prescribed aspirin.

Observations and Results

There was a reduction in relative risk of preeclampsia in aspirin group as compared with control group. There was no significant increase in the number of cases of abruption placenta, preterm delivery, neonatal intraventricular hemorrhage, patent ductus arteriosus, and postpartum hemorrhage following aspirin therapy.

Conclusion

In patients with high mean pulsatility index of uterine arteries, low dose aspirin can be a useful intervention. Uterine artery Doppler is a simple and noninvasive test which can be used safely for the prediction of preeclampsia. Aspirin is safe, economical, and easily available commercially.

Should We Add Pravastatin to Aspirin for Preeclampsia Prevention in High-risk Women?

Preeclampsia is a multisystem disorder that affects 3% to 5% of pregnant women and remains a significant source of short-term and long-term maternal and neonatal mortality and morbidity. Many professional societies recommend the use of low-dose aspirin to prevent preeclampsia in high-risk women. Owing to the similarities in pathophysiology between preeclampsia and atherosclerotic cardiovascular disease, and the encouraging data from preclinical and pilot clinical studies, pravastatin has been proposed for preventing preeclampsia. However, before statin administration becomes part of routine clinical practice, a large, well-designed, and adequately powered randomized-controlled trial is needed.

Antiplatelet therapy before or after 16 weeks' gestation for preventing preeclampsia: an individual participant data meta-analysis

BACKGROUND

The optimum time for commencing antiplatelet therapy for the prevention of preeclampsia and its complications is unclear. Aggregate data meta-analyses suggest that aspirin is more effective if given prior to 16 weeks' gestation, but data are limited because of an inability to place women in the correct gestational age subgroup from relevant trials.

OBJECTIVE

The objective of the study was to use the large existing individual participant data set from the Perinatal Antiplatelet Review of International Studies Collaboration to assess whether the treatment effects of antiplatelet agents on preeclampsia and its complications vary based on whether treatment is started before or after 16 weeks' gestation.

STUDY DESIGN

A meta-analysis of individual participant data including 32,217 women and 32,819 babies recruited to 31 randomized trials comparing low-dose aspirin or other antiplatelet agents with placebo or no treatment for the prevention of preeclampsia has been published previously. Using this existing data set, we performed a prespecified subgroup analysis based on gestation at randomization to antiplatelet agents before 16 weeks, compared with at or after 16 weeks, for 4 of the main outcomes prespecified in the Perinatal Antiplatelet Review of International Studies protocol: preeclampsia, death of baby, preterm birth before 34 weeks, and small-for-gestational-age baby. Individual participant data for the subgroups were combined in a meta-analysis using RevMan software. Heterogeneity was assessed with the I² statistic. The χ² test for interaction was used to assess statistically significant (P < .05) differences in treatment effect between subgroups.

RESULTS

There was no significant difference in the effects of antiplatelet therapy for women randomized before 16 weeks' gestation compared with those randomized at or after 16 weeks for any of the 4 prespecified outcomes: preeclampsia, relative risk, 0.90, (95% confidence interval, 0.79-1.03; 17 trials, 9241 women) for <16 weeks and relative risk, 0.90 (95% confidence interval, 0.83-0.98; 22 trials, 21,429 women) for ≥16 weeks (interaction test, P = .98); death of baby, relative risk, 0.89 (95% confidence interval, 0.73-1.09; 15 trials, 8626 women) for <16 weeks and relative risk, 0.92 (95% confidence interval, 0.79-1.07; 21 trials, 22,336 women) for ≥16 weeks (interaction test, P = .80); preterm birth prior to 34 weeks, relative risk, 0.90 (95% confidence interval, 0.77-1.04; 19 trials, 9155 women) for <16 weeks and relative risk, 0.91 (95% confidence interval, 0.82-1.00; 25 trials, 22,117 women) for ≥16 weeks (interaction test, P = .91); and small-for-gestational-age baby, relative risk, 0.76 (95% confidence interval, 0.61-0.94; 13 trials, 6393 women) for <16 weeks and relative risk, 0.95 (95% confidence interval, 0.84-1.08; 18 trials, 14,996 women) for ≥16 weeks (interaction test, P = .08).

CONCLUSION

The effect of low-dose aspirin and other antiplatelet agents on preeclampsia and its complications is consistent, regardless of whether treatment is started before or after 16 weeks' gestation. Women at an increased risk of preeclampsia should be offered antiplatelet therapy, regardless of whether they are first seen before or after 16 weeks' gestation.

First trimester screening for pre-eclampsia

The commercial availability of tests in the first trimester of pregnancy that predict the later development of pre-eclampsia has prompted considerable debate regarding their clinical utility and the degree to which they fulfil the longstanding principles of screening. Such tests have been shown to achieve detection rates for early pre-eclampsia (requiring delivery prior to 34 weeks) of over 90%, for a false positive rate of 10%. However, their capacity to predict later onset pre-eclampsia, which accounts for the bulk of the disease burden, is much more limited. The relatively few studies validating the performance of these tests in different populations have demonstrated significant variations in performance. Moreover, prospective research confirming that the administration of aspirin to those screened to be high risk reduces the incidence of pre-eclampsia is yet to be completed, and there may be harms in restricting aspirin therapy to this group, given its broader beneficial effect. In light of these limitations, further development of these tests is recommended prior to their introduction to clinical practice.

Prediction and prevention of ischemic placental disease

Preeclampsia, intrauterine growth restriction (IUGR), and placental abruption are obstetrical conditions that constitute the syndrome of ischemic placental disease or IPD, the leading cause of indicated preterm birth and an important cause of neonatal morbidity and mortality. While the phenotypic manifestations vary significantly for preeclampsia, IUGR, and abruption, these conditions may share a common underlying etiology as evidenced by: (1) shared clinical risk factors, (2) increased recurrence risk across pregnancies as well as increased co-occurrence of IPD conditions within a pregnancy, and (3) findings that suggest the underlying pathophysiologic processes may be similar. IPD is of major clinical importance and accounts for a large proportion of indicated preterm delivery ranging from the periviable to late preterm period. Successful prevention of IPD and resultant preterm delivery could substantially improve neonatal and maternal outcomes. This article will review the following topics: (1) The complicated research literature on aspirin and the prevention of preeclampsia and IUGR. (2) Research evidence on other medical interventions to prevent IPD. (3) New clinical interventions currently under investigations, including statins. (4) Current clinical recommendations for prevention of ischemic placental disease.

New directions in the prediction of pre-eclampsia

Pre-eclampsia remains an important worldwide cause of maternal and perinatal morbidity and mortality. Improved prediction of those destined to develop this condition would allow for timely initiation of prophylactic therapy, appropriate antenatal surveillance and better targeted research into preventive interventions. This paper reviews recent research into strategies for the prediction of pre-eclampsia, including the use of maternal risk factors, mean maternal arterial pressure, ultrasound parameters and biomarkers. The most promising strategies involve multiparametric approaches, which use a variety of individual parameters in combination, as has been established in first-trimester aneuploidy screening. The paper concludes with a discussion of the issues around the introduction of such testing into clinical practice.