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

Objective: A systolic blood pressure (SBP) threshold  160 mmHg is used in pregnancy for acute anti-hypertensive treatment; however, this was initially adapted from expert opinion and guidelines for non-pregnant adults support a SBP  180 mmHg. We compared adverse maternal outcomes using a SBP threshold of  180 mmHg versus  160 mmHg for acute anti-hypertensive treatment, while treating SBPs between 160-179 mmHg (DBP  110 mmHg) with oral maintenance anti-hypertensives. Study Design: We performed a Quality Improvement before and after non-inferiority study (NCT05881252) of singletons  20 weeks’ with SBP  160 mmHg 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 mmHg (or DBP  110 mmHg). In the after group, oral maintenance antihypertensives (labetalol or extended-release nifedipine) were given if persistent SBP between 160-179 mmHg (DBP  110 mmHg) and acute antihypertensives for persistent SBP  180 mmHg (or DBP  110 mmHg). 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 non-inferiority margin of 4% and 1% (posthoc sensitivity analysis). Results: We studied 1,002 individuals (410 in before; 592 in after) with severe hypertension. The primary outcome occurred in 2.9% of the before 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 3-fold in the after group (mean 1.7 doses versus 0.6, p<0.01) Conclusion: In our population, treating SBPs between 160-180 mmHg with oral maintenance antihypertensives resulted in to a non-inferior rate of maternal adverse outcomes and decreased the use of