Background: High-quality evidence to inform the management of postpartum hypertension, including the optimal blood pressure threshold to initiate therapy, is lacking. Randomized trials have been conducted in pregnancy, but there are no published trials to guide management in the postpartum period.
Objective: This study aimed to test the hypothesis that initiating antihypertensive therapy in the postpartum period at a threshold of 140/90 mm Hg would result in less maternal morbidity than initiating therapy at a threshold of 150/95 mm Hg.
Study design: We performed a pragmatic multicenter randomized controlled trial of patients aged 18 to 55 years with postpartum hypertension. Patients with chronic hypertension, gestational hypertension, and preeclampsia without severe features were randomized to 1 of 2 blood pressure thresholds to initiate treatment: persistent blood pressure of ≥150/95 mm Hg (institutional standard or "liberal control" group) or ≥140/90 mm Hg (intervention or "tight control" group). Our primary outcome was composite maternal morbidity defined as: severe hypertension (blood pressure ≥160/110 mm Hg) or preeclampsia with severe features, the need for a second antihypertensive agent, postpartum hospitalization >4 days, and maternal adverse outcome secondary to hypertension as evidenced by pulmonary edema, acute kidney injury (creatinine level ≥1.1 mg/dL), cardiac dysfunction (eg, elevated brain natriuretic peptide level) or cardiomyopathy, posterior reversible encephalopathy syndrome, cerebrovascular accident, or admission to an intensive care unit. Secondary outcomes included hospital readmission for hypertension, persistence of hypertension beyond 14 days, medication side effects, and time to blood pressure control. We calculated that 256 women would provide 90% power to detect a relative 50% reduction in the primary outcome from 36% in the standard blood pressure threshold group to 18%, with a 2-sided alpha set at 0.05 for significance. Data were analyzed using R statistical software.
Results: A total of 256 patients were randomized, including 128 to the "tight control" group (140/90 mm Hg) and 128 to the "liberal control" group (150/95 mm Hg). Patients in the "tight control" group had a higher body mass index at delivery (37.1±9.4 vs 34.9±8.1; P=.04); other demographic and obstetrical characteristics were similar between groups. The rate of the primary outcome was similar between groups (8.6% vs 11.7%; P=.41; relative risk, 0.73; 95% confidence interval, 0.35-1.53). The rates of all secondary outcomes and the individual components of the primary and secondary outcome measures were also similar between groups.
Conclusion: In the postpartum period, initiation of antihypertensive therapy at a lower blood pressure threshold of 140/90 mm Hg did not decrease maternal morbidity or improve outcomes compared with a threshold of 150/95 mm Hg.
Keywords: antihypertensive medication; blood pressure; blood pressure threshold; postpartum hypertension; severe hypertension.
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