Are anticonvulsants necessary to prevent eclampsia?

Magnesium sulphate and other anticonvulsants for women with pre-eclampsia

BACKGROUND

Eclampsia, the occurrence of a seizure (fit) in association with pre-eclampsia, is rare but potentially life-threatening. Magnesium sulphate is the drug of choice for treating eclampsia. This review assesses its use for preventing eclampsia.

OBJECTIVES

To assess the effects of magnesium sulphate, and other anticonvulsants, for prevention of eclampsia.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (4 June 2010), and the Cochrane Central Register of Controlled Trials Register (The Cochrane Library 2010, Issue 3).

SELECTION CRITERIA

Randomised trials comparing anticonvulsants with placebo or no anticonvulsant, or comparisons of different drugs, for pre-eclampsia.

DATA COLLECTION AND ANALYSIS

Two authors assessed trial quality and extracted data independently.

MAIN RESULTS

We included 15 trials. Six (11,444 women) compared magnesium sulphate with placebo or no anticonvulsant: magnesium sulphate more than a halved the risk of eclampsia (risk ratio (RR) 0.41, 95% confidence interval (CI) 0.29 to 0.58; number needed to treat for an additional beneficial outcome (NNTB) 100, 95% CI 50 to 100), with a non-significant reduction in maternal death (RR 0.54, 95% CI 0.26 to 1.10) but no clear difference in serious maternal morbidity (RR 1.08, 95% CI 0.89 to 1.32). It reduced the risk of placental abruption (RR 0.64, 95% CI 0.50 to 0.83; NNTB 100, 95% CI 50 to 1000), and increased caesarean section (RR 1.05, 95% CI 1.01 to 1.10). There was no clear difference in stillbirth or neonatal death (RR 1.04, 95% CI 0.93 to 1.15). Side effects, primarily flushing, were more common with magnesium sulphate (24% versus 5%; RR 5.26, 95% CI 4.59 to 6.03; number need to treat for an additional harmful outcome (NNTH) 6, 95% CI 5 to 6).Follow-up was reported by one trial comparing magnesium sulphate with placebo: for 3375 women there was no clear difference in death (RR 1.79, 95% CI 0.71 to 4.53) or morbidity potentially related to pre-eclampsia (RR 0.84, 95% CI 0.55 to 1.26) (median follow-up 26 months); for 3283 children exposed in utero there was no clear difference in death (RR 1.02, 95% CI 0.57 to 1.84) or neurosensory disability (RR 0.77, 95% CI 0.38 to 1.58) at age 18 months.Magnesium sulphate reduced eclampsia compared to phenytoin (three trials, 2291 women; RR 0.08, 95% CI 0.01 to 0.60) and nimodipine (one trial, 1650 women; RR 0.33, 95% CI 0.14 to 0.77).

AUTHORS' CONCLUSIONS

Magnesium sulphate more than halves the risk of eclampsia, and probably reduces maternal death. There is no clear effect on outcome after discharge from hospital. A quarter of women report side effects with magnesium sulphate.

Magnesium sulphate and other anticonvulsants for women with pre-eclampsia

BACKGROUND

Pre-eclampsia is a relatively common complication of pregnancy. Eclampsia, the occurrence of one or more convulsions (fits) in association with the syndrome of pre-eclampsia, is a rare but serious complication. Anticonvulsants are used in the belief they help prevent eclamptic fits and so improve outcome.

OBJECTIVES

The objective was to assess the effects of anticonvulsants for pre-eclampsia on the women and their children.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register (28 November 2002), and the Cochrane Controlled Trials Register (The Cochrane Library, Issue 3, 2002).

SELECTION CRITERIA

Randomised trials comparing anticonvulsants with placebo or no anticonvulsants or comparisons of different anticonvulsants in women with pre-eclampsia.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed trial quality and extracted data independently.

MAIN RESULTS

Six trials (11,444 women) compared magnesium sulphate with placebo or no anticonvulsant. There was more than a halving in the risk of eclampsia associated with magnesium sulphate (relative risk (RR) 0.41, 95% confidence interval (CI) 0.29 to 0.58; number needed to treat (NNT) 100, 95% CI 50 to 100). The risk of dying was non-significantly reduced by 46% for women allocated magnesium sulphate (RR 0.54, 95% CI 0.26 to 1.10). For serious maternal morbidity RR 1.08, 95% CI 0.89 to 1.32. Side effects were more common with magnesium sulphate (24% versus 5%; RR 5.26, 95% CI 4.59 to 6.03; NNT for harm 6, 95% CI 6 to 5). The main side effect was flushing. Risk of placental abruption was reduced for women allocated magnesium sulphate (RR 0.64, 95% CI 0.50 to 0.83; NNT 100, 95% CI 50 to 1000). Women allocated magnesium sulphate had a small increase (5%) in the risk of caesarean section (95% CI 1% to 10%). There was no overall difference in the risk of stillbirth or neonatal death (RR 1.04, 95% CI 0.93 to 1.15). Magnesium sulphate was better than phenytoin for reducing the risk of eclampsia (two trials 2241 women; RR 0.05, 95% CI 0.00 to 0.84), but with an increased risk of caesarean section (RR 1.21, 95% CI 1.05 to 1.41). It was also better than nimodipine (1 trial, 1650 women; RR 0.33, 95% CI 0.14 to 0.77).

REVIEWER'S CONCLUSIONS

Magnesium sulphate more than halves the risk of eclampsia, and probably reduces the risk of maternal death. It does not improve outcome for the baby, in the short term. A quarter of women have side effects, particularly flushing.

Preeclampsia into eclampsia: toward a new paradigm

OBJECTIVE

This study was undertaken to characterize aspects of the natural history of eclampsia.

STUDY DESIGN

A retrospective analysis was performed on the records of patients with eclampsia who were delivered at two tertiary care hospitals.

RESULTS

Fifty-three pregnancies complicated by eclampsia were identified. Thirty-seven of the women were nulliparous. The mean age was 22 years (range, 15-38 years). Mean gestational age at the time of seizures was 34.2 weeks' gestation (range, 22-43 weeks' gestation). Twenty-eight women had antepartum seizures (53%); 23 of the 28 had seizures at home. Nineteen women had intrapartum seizures (36%). Eight of these women had seizures while receiving magnesium sulfate, and 7 had therapeutic magnesium levels. Six women had postpartum seizures (11%), 4 >24 hours after delivery. Headache preceded seizures in 34 cases. Visual disturbance preceded seizures in 16 cases. The uric acid level was elevated to >6 mg/dL in 43 women. There were no maternal deaths or permanent morbidities. There were 4 perinatal deaths. Two patients had intrauterine fetal deaths at 28 and 36 weeks' gestation. These mothers had seizures at home. One infant died of complications of prematurity at 22 weeks' gestation and one died of respiratory complications at 26 weeks' gestation. There were 4 cases of abruptio placentae, 1 of which resulted in fetal death. Of the 53 cases of eclampsia, only 9 were potentially preventable. One of these was that of a woman who was being observed at home. The other 8 women were hospitalized and had hypertension and proteinuria. Only 7 women could be considered to have severe preeclampsia before seizure (13%), and 4 of these 7 women were receiving magnesium sulfate.

CONCLUSIONS

Eclampsia was not found to be a progression from severe preeclampsia. In 32 of 53 cases (60%) seizures were the first signs of preeclampsia. In this series eclampsia appeared to be more of a subset of preeclampsia. Only 9 cases of eclampsia were potentially preventable with current standards of practice. Our paradigm for this disease, as well as our approach to seizure prophylaxis, should be reevaluated.

The feasibility of a control population for a randomized control trial of seizure prophylaxis in the hypertensive disorders of pregnancy

OBJECTIVE

To document the feasibility of a control population for a randomized controlled trial, we report our experience in managing hypertensive pregnancies without seizure prophylaxis.

STUDY DESIGN

An 8-year cross-sectional study in one institution was performed of all hypertensive patients.

RESULTS

Of 467 patients with preeclampsia or superimposed preeclampsia managed without seizure prophylaxis, 18 had seizure activity, 3.9% (95% confidence interval 2.3% to 6.0%). There was no seizure-related maternal mortality or major morbidity, and the perinatal mortality rate after 28 gestational weeks was the same in patients with or without seizures. By logistic regression seizures were 17.4 times more likely in preeclampsia and 8.1 times more likely in chronic hypertension with superimposed preeclampsia, compared with gestational or chronic hypertension alone.

CONCLUSION

The rate of seizures in patients with preeclampsia or superimposed preeclampsia managed without seizure prophylaxis was low and unassociated with an increase in maternal or perinatal mortality. A control arm is feasible in a randomized, controlled trial to address the issue of whether antiseizure medication can prevent eclampsia.