The impact of pre-eclampsia definitions on the identification of adverse outcome risk in hypertensive pregnancy - analyses from the CHIPS trial (Control of Hypertension in Pregnancy Study)

OBJECTIVE

To examine the association between pre-eclampsia definition and pregnancy outcome.

DESIGN

Secondary analysis of Control of Hypertension in Pregnancy Study (CHIPS) trial data.

SETTING

International multicentre randomised controlled trial (RCT).

POPULATION

In all, 987 women with non-severe non-proteinuric pregnancy hypertension.

METHODS

We evaluated the association between pre-eclampsia definitions and adverse pregnancy outcomes, stratified by hypertension type and blood pressure control.

MAIN OUTCOME MEASURES

Main CHIPS trial outcomes: primary (perinatal loss or high-level neonatal care for >48 hours), secondary (serious maternal complications), birthweight <10th centile, severe maternal hypertension, delivery at <34 or <37 weeks, and maternal hospitalisation before birth.

RESULTS

Of 979/987 women with informative data, 280 (28.6%) progressed to pre-eclampsia defined restrictively by new proteinuria, and 471 (48.1%) to pre-eclampsia defined broadly as proteinuria or one/more maternal symptoms, signs or abnormal laboratory tests. The broad (versus restrictive) definition had significantly higher sensitivities (range 62-79% versus 36-50%), lower specificities (range 53-65% versus 72-82%), and similar or higher diagnostic odds ratios and 'true-positive' to 'false-positive' ratios. Stratified analyses showed similar results. Addition of available fetoplacental manifestations (stillbirth or birthweight <10th centile) to the broad pre-eclampsia definition improved sensitivity (74-87%).

CONCLUSIONS

A broad (versus restrictive) pre-eclampsia definition better identifies women who develop adverse pregnancy outcomes. These findings should be replicated in a prospective study within routine healthcare to ensure that the anticipated increase in surveillance and intervention in a larger number of women with pre-eclampsia is associated with improved outcomes, reasonable costs and congruence with women's values.

TWEETABLE ABSTRACT

A broad (versus restrictive) pre-eclampsia definition better identifies the risk of adverse pregnancy outcomes.