Aspirin of Small Benefit in Preventing Preeclampsia

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Aspirin of Small Benefit in Preventing Preeclampsia

Although the etiology of preeclampsia is unknown, it is clear that the disorder is associated with decreased intravascular production of the vasodilator prostacyclin and increased production of the vasoconstrictor thromboxane. This association led to the hypothesis that antiplatelet drugs, particularly aspirin, might prevent preeclampsia or might reduce the associated morbidity. Because the results of randomized trials have been mixed, these researchers conducted a systematic review to assess the efficacy of aspirin in preventing preeclampsia and its complications.

This analysis included 39 trials that involved 30,563 women. Use of aspirin (generally, <75 mg) was associated with a 15 percent reduction in the risk for preeclampsia. In addition, there was an 8 percent reduction in the risk for preterm birth and a 14 percent reduction in the risk for fetal or neonatal death. All of these risk reductions were statistically significant.

Comment: The reviewers were careful to note that the true benefit of beginning antiplatelet drugs early in gestation -- particularly among women at risk for preeclampsia -- cannot be determined from the studies conducted to date. Although the benefits identified are modest at best, they may be greater in women at increased risk for preeclampsia.

RW Rebar
Published in Journal Watch General Medicine March 13, 2001 Citation(s): Duley L et al. Antiplatelet drugs for prevention of pre-eclampsia and its consequences: Systematic review. BMJ 2001 Feb 10 322 329-333.

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Antiplatelet drugs for prevention of pre-eclampsia and its consequences: systematic review.
Duley L, Henderson-Smart D, Knight M, King J.

Resource Centre for Randomised Trials, Institute of Health Sciences, Oxford OX3 7LF. lelia.duley@ndm.ox.ac.uk

OBJECTIVE: To assess the effectiveness and safety of antiplatelet drugs for prevention of pre-eclampsia and its consequences.

DESIGN: Systematic review.

DATA SOURCES: Register of trials maintained by Cochrane Pregnancy and Childbirth Group, Cochrane Controlled Trials Register, and Embase.

INCLUDED STUDIES: Randomised trials involving women at risk of pre-eclampsia, and its complications, allocated to antiplatelet drug(s) versus placebo or no antiplatelet drug. MAIN

OUTCOME MEASURES: Pre-eclampsia, preterm birth, fetal or neonatal death, and small for gestational age baby. Studies were assessed for quality of concealment of allocation and losses to follow up.

RESULTS: 39 trials (30 563 women) were included, and 45 trials (>3000 women) excluded. Use of antiplatelet drugs was associated with a 15% reduction in the risk of pre-eclampsia (32 trials, 29 331 women; relative risk 0.85, 95% confidence interval 0.78 to 0.92; number needed to treat 100, 59 to 167). There was also an 8% reduction in the risk of preterm birth (23 trials, 28 268 women; 0.92, 0.88 to 0.97; 72, 44 to 200), and a 14% reduction in the risk of fetal or neonatal death (30 trials, 30 093 women; 0.86, 0.75 to 0.98; 250, 125 to >10 000) for women allocated antiplatelet drugs. Small for gestational age babies were reported in 25 trials (20 349 women), with no overall difference between the groups (relative risk 0.92, 0.84 to 1.01). There were no significant differences in other measures of outcome.

CONCLUSIONS: Antiplatelet drugs, largely low dose aspirin, have small to moderate benefits when used for prevention of pre-eclampsia.