Oral Maintenance Anti-Hypertensives for Severe Systolic Hypertension: A Controlled Before-and-After Quality Improvement Study

Abstract

Abstract A systolic blood pressure (SBP) threshold ≥ 160 mm Hg is used in pregnancy for acute antihypertensive treatment; however, this was initially adapted from expert opinion, and guidelines for nonpregnant adults support an SBP ≥ 180 mm Hg. We compared adverse maternal outcomes using a SBP threshold of ≥ 180 mm Hg versus ≥ 160 mm Hg for acute anti-hypertensive treatment, while treating SBPs between 160 and 179 mm Hg (diastolic blood pressure [DBP] < 110) with oral maintenance anti-hypertensives. We performed a quality improvement before-and-after noninferiority study (NCT05881252) of singletons ≥ 20 weeks' with SBP ≥ 160 mm Hg at a single level 4 medical center. In the before group, acute antihypertensives (intravenous [IV] labetalol/hydralazine or rapid-acting oral nifedipine) were given for persistent SBP ≥ 160 mm Hg (or DBP ≥ 110). In the after group, oral maintenance antihypertensives (labetalol or extended-release nifedipine) were given if persistent SBP was between 160 and 179 mm Hg (DBP < 110) and acute antihypertensives for persistent SBP ≥ 180 mm Hg (or DBP ≥ 110). The primary outcome was a composite of congestive heart failure, pulmonary edema, cerebrovascular accident, acute kidney injury, or myocardial infarction. Bayesian analysis was performed using a noninferiority margin of 4 and 1% (post hoc sensitivity analysis). We studied 1,002 individuals (410 in before; 592 in after) with severe hypertension. The primary outcome occurred in 2.9% of the before group and 1.9% of the after group (0.72: median relative risk, 95% credible interval: 0.36–1.46), with an 82% probability of risk reduction in the after group and > 99.9% probability that the risk difference in the after group was < 4% (99% for a 1% margin). Use of acute antihypertensives per individual treated decreased almost threefold in the after group (mean: 1.7 doses vs. 0.6, p < 0.01) In our population, treating SBPs between 160 and 180 mm Hg with oral maintenance antihypertensives resulted in a noninferior rate of maternal adverse outcomes and decreased the use of IV/rapid acting medication.