Association between Initial Propranolol Dose and Blood Pressure Control in 48 to 72 Hours Among Preterm Infants with Hypertension

OBJECTIVES: Frequently preterm infant hypertension is treated with propranolol, but the optimal initial dose is unclear. We assessed differences in mean arterial pressure 48-72 hours after initiation of propranolol among different initial doses.

METHODS: We performed a retrospective cohort study of inpatient preterm infants who received an antihypertensive therapy. We obtained the dataset via electronic medical records from the University of Alabama at Birmingham. We identified new users of propranolol with doses of 0.25, 0.5, and 1 mg/kg. We excluded recipients of other antihypertensive drugs and infants diagnosed with hemangioma before initiating propranolol. Our primary outcome was mean arterial 48-72 hours after initiating propranolol. We used a Bayesian linear regression model for this outcome, adjusting for baseline mean arterial pressure and gestational age at birth. We considered a mean difference of 5 mmHg in the primary outcome as a clinically relevant difference among the three initial.

RESULTS: Our cohort included 55 patients (16 patients initiated 1 mg/kg, 17 patients initiated 0.5 mg/kg, and 12 patients initiated 0.25 mg/kg). The adjusted mean difference between 1 mg/kg and 0.5 /kg was -1.1 mmHg (90% credible intervals: -3.7 mmHg, 1.5 mmHg). The probability that the 1 mg/kg dose had a clinically meaningful benefit compared to the 0.5 mg/kg dose was 3.8%. The adjusted mean difference between 1mg/kg and 0.25 mg/kg was 1.2 mmHg (90% credible intervals: -1.6 mmHg, 4.0 mmHg). The probability that the 1 mg/kg dose had a clinically meaningful benefit compared to the 0.25 mg/kg dose was 0.3%.

CONCLUSIONS: Our results suggest that for preterm infants being treated for hypertension, a higher propranolol dose of 1 mg/kg versus a lower dose of 0.5 mg/kg or 0.25 mg/kg is unlikely to be associated with meaningfully better mean arterial pressure control within 48 to 72.