Amlodipine versus nifedipine ER for the management of postpartum hypertension: a noninferiority randomized controlled trial

Abstract

Background

Postpartum hypertension is an increasingly prevalent problem and optimizing its treatment is imperative in reducing maternal morbidity and improving long-term health outcomes. Despite this, data on treatment of postpartum hypertension is limited. While most available studies focus on labetalol and nifedipine ER, these medications are not frequently used for hypertension treatment in the non-obstetric setting. As we aim to establish best practices for managing postpartum hypertension, use of more commonly encountered antihypertensives should be evaluated.

Objective

To evaluate the use of amlodipine for the treatment of postpartum hypertension, as assessed by postpartum length of stay.

Study Design

In a pragmatic, randomized controlled noninferiority trial, patients were assigned to amlodipine or nifedipine ER for treatment of postpartum hypertension. The primary outcome was time from delivery until discharge with a noninferiority limit of 24 hours. A sample size of 132 was needed to achieve 80% power with a 2-tailed alpha of 0.05. Intent-to-Treat and Per Protocol analyses were performed. Prespecified secondary outcomes included the need for additional antihypertensives, side effects, medication discontinuation, breastfeeding satisfaction, and readmission rate. A post-hoc analysis of time from medication initiation until hospital discharge was also performed.

Results

From April 2021 to December 2022, 7618 patients were screened and 175 patients were randomized, with 132 meeting criteria for antihypertensive initiation. Baseline demographics were similar between groups. Amlodipine had a non-inferior length of stay compared to nifedipine ER (Intent-to-Treat Wilcoxon pseudo-median amlodipine=73.5 hours, nifedipine ER=72.0 hours, 95% CI -8.00 to 6.00). The remainder of analyses were performed only on the Per Protocol cohort. Time from medication initiation until hospital discharge was similar between groups (amlodipine=45.0 hours, nifedipine ER=45.5 hours, 95% CI -8.00 to 13.00). There were no differences in use of additional antihypertensives or patient-reported side effects or breastfeeding outcomes, but hypotension and tachycardia were less common with amlodipine use. Amlodipine was significantly less likely to be discontinued due to side effects (amlodipine n=0, nifedipine ER n=7 (10.1%), p=.02). Readmission rates were similar between groups.

Conclusion

Amlodipine is noninferior to nifedipine ER for postpartum hypertension treatment, as defined by median length of postpartum stay. Rates of side effects were similar between groups, but there was a statistically significant difference in medication discontinuation rates.

Clinical trial registration: Clinicaltrials.gov, www.clinicaltrials.gov, NCT04790279

El resumen está disponible en Español al final del artículo.