Pulse pressure as a predictor of response to treatment for severe hypertension in pregnancy.

BACKGROUND

Pulse pressure is a proposed means of tailoring antihypertensive therapy for treatment of acute-onset, severe hypertension in pregnancy.

OBJECTIVE

This study aimed to determine whether pulse pressure predicts response to the various first-line antihypertensive medications.

STUDY DESIGN

This is a retrospective cohort study from a single academic tertiary care center between 2015 and 2018. Patients were screened for inclusion if they had severe hypertension (defined as systolic blood pressure of ≥160 mm Hg or diastolic blood pressure of ≥110 mm Hg) lasting at least 15 minutes and were initially treated with intravenous labetalol, intravenous hydralazine, or immediate-release oral nifedipine. If a patient had multiple episodes of acute treatment during the pregnancy, only one episode was included in the analysis. The primary outcome was time to resolution (in minutes) of severe hypertension. To adjust for factors that may have affected time to resolution, we first compared baseline characteristics on the basis of the antihypertensive agent received. We then assessed the association between baseline characteristics and resolution of severe hypertension within 60 minutes of treatment. Regression analysis incorporated pulse pressure and antihypertensive agents into a model to predict resolution within 60 minutes of onset of severe hypertension.

RESULTS

A total of 479 women hospitalized with severe maternal hypertension met the inclusion criteria. Hydralazine was the initial antihypertensive agent administered to 113 women, whereas 233 received labetalol, and 133 received nifedipine. Those who initially received nifedipine had a shorter mean time to resolution of severe hypertension (32.6 minutes vs 46.3 for hydralazine and 50.3 for labetalol; P<.01) and were more likely to have resolution of severe hypertension within 60 minutes (91.0% vs 77.9% for hydralazine and 76.8% for labetalol; P<.01). Nifedipine also resulted in a lower mean posttreatment blood pressure. Regression analysis revealed that a lack of resolution of severe hypertension within 60 minutes was independently associated with 2 measures of hypertension severity (mean arterial pressure of ≥125 mm Hg and the need for ≥2 doses of medication) and pulse pressure of >75 mm Hg at the time of treatment, initial treatment with labetalol, and gestational age of <37 weeks at the time of the hypertensive event (or at delivery if treatment was after delivery). The model's bias-corrected bootstrapped area under the receiver operating characteristic curve was 0.85 (95% confidence interval, 0.79-0.88). Interaction terms between pulse pressure and each antihypertensive agent were not significant and therefore not incorporated into the final model.

CONCLUSION

Pulse pressure did not predict response to the various first-line antihypertensive agents. Initial treatment with oral nifedipine was associated with a higher likelihood of resolution of severe hypertension within 60 minutes of treatment than with intravenous labetalol.