Surveillance and case control study of eclampsia

Summary

A national survey of eclampsia in 1992 recorded a UK incidence of 4.9/10,000 maternities with a case fatality rate of 1.8%. Since this study took place there have been major advances in management of eclampsia. However, there were no current data on the epidemiology and management of non-fatal eclampsia in the UK to identify the extent to which these advances had been adopted and the impact on disease incidence. This information is key to identifying means to improve prevention and quality of care. This study showed that the incidence of eclampsia and its complications have decreased significantly in the UK since 1992, following the introduction of management guidelines for eclampsia and pre-eclampsia. These results are consistent with the findings of the randomised controlled trials of magnesium sulphate. This study revealed the practical benefits of the incorporation of research evidence into practice.

Delayed postpartum eclampsia

The overall rate of eclampsia in developed countries has declined; however, the proportion of cases of eclampsia occurring postpartum is thought to have increased. Trends towards decreasing lengths of postnatal hospital stay have led to concerns about possible adverse effects of such early discharge, including risks of morbidity from hypertensive disorders. The aim of this analysis was to use the data from the 2005-6 UKOSS eclampsia study to estimate the incidence of delayed postpartum eclampsia and to investigate whether maternal characteristics and outcomes were different between women with delayed (12 hours or longer after delivery) or early postpartum eclampsia.

Key findings

• Seventy-six women had postpartum eclampsia, representing an incidence of 1.0/10 000 (95% CI 0.7–1.2/10 000) maternities.
• Among the women having postpartum eclampsia, 70% (n=53) of women had their first fit in the 12 hours immediately following delivery, 11% (n=8) during hours 12–24, 5% (n=4) during the 24–48 hours after delivery and14% (n=11) more than 48 hours after delivery.
• Maternal characteristics, biological and clinical symptoms in the week preceding eclampsia, maternal and neonatal outcomes were not significantly different in the delayed eclampsia group in comparison with the early postpartum eclampsia group, with the exception of a higher caesarean delivery rate in women with delayed eclampsia [13 (57%) vs. 6 (11%); odds ratio 10.1, 95% CI 3.12–33.3].
• This study suggests that the majority of cases of postpartum eclampsia in the UK occur in the first 12 hours following delivery. Beyond this, the risk of eclampsia is very low.

Publications

Journal Articles

• Knight M, on behalf of UKOSS. Eclampsia in the United Kingdom 2005. Br J Obstet Gynaecol. 2007;114:1072-8.
• Knight M. Preeclampsia: Increasing Incidence but Improved Outcome? Am J Hypertens. 2008;21(5):491.
• Knight M. Studies using routine data versus specific data collection: What can we learn about the epidemiology of eclampsia and the impact of changes in management of gestational hypertensive disorders? Pregnancy Hypertens. 2011;1:109-16.
• Kayem G, Kurinczuk JJ, Spark P, Brocklehurst P, Knight M, System UKOS. Maternal and obstetric factors associated with delayed postpartum eclampsia: a national study population. Acta Obstet Gynecol Scand. 2011;90(9):1017-23.