A prediction model for the response to oral labetalol for the treatment of antenatal hypertension.

Abstract

This prospective observational study aimed to identify at presentation the maternal hemodynamic and demographic variables associated with a therapeutic response to oral labetalol and to use these variables to develop a prediction model to anticipate the response to labetalol monotherapy in women with hypertension. It was set at a maternity unit in a UK teaching hospital. Maternal demographic data from 50 pregnant women, presenting with hypertension between January and August 2013, was collected and blood pressure measured with a device validated for pregnancy and pre-eclampsia. Maternal haemodynamics were assessed with a bioreactance monitor. Participants were commenced on oral labetalol, and reviewed until delivery and discharge home. Logistic regression analysis was performed to assess the prediction of response to labetalol according to the maternal demographic and hemodynamic variables. Main outcome measures were the response to labetalol monotherapy up to delivery and discharge home, defined as sustained blood pressure control <140/90, and the rates of severe hypertension. Thirty-seven women (74%) had their blood pressure well controlled with labetalol monotherapy, 13 (26%) failed to achieve control with labetalol alone, of whom 9 developed severe hypertension. Multivariate logistic regression showed that heart rate, ethnicity and stroke volume index were independent predictors of the response to labetalol. The predictive accuracy of the model was 96% (95% confidence interval (CI) 86-99%). Maternal demographics and haemodynamics are potent predictors for the response to labetalol, and these parameters may guide therapy to enable effective blood pressure control and a lowering of severe hypertension rates.