Medication fill duration in pediatric hypertension: adherence, blood pressure control, and disparities

Medication nonadherence is a barrier to hypertension control. The Centers for Disease Control and Prevention recommends prescribing 90-day fills for maintenance medications yet antihypertensives are often dispensed as 30-day fills. Our objectives were to examine how often patients receive 30-day supplies of medication despite prescriptions for longer duration and to examine the effect of medication fill duration on adherence and hypertension control.

We conducted a retrospective cohort study of pediatric patients with hypertension over a 3-year period. For each patient, days prescribed per fill were compared to days dispensed per fill using pharmacy reports and insurance claim data. Proportion of Days Covered (PDC) was calculated to estimate adherence. Hypertension control was determined by provider assessment of control and blood pressure measurement at the final visit.

Final cohort included 449 patients. A total of 70% had at least one prescription for ≥ 90 days but only 37% had at least one dispense for ≥ 90 days. There was no difference in the likelihood of being prescribed a 90-day fill by insurance type (public vs. private); however, patients with public insurance were less likely to be dispensed a 90-day fill (OR = 0.068, p < 0.001). Patients who received 90-day fills had better adherence (median PDC 77.5% vs. 58.1%, p < 0.001) and were more likely to have hypertension control based on provider assessment.

Longer fill duration is associated with improved adherence and hypertension control. Patients with public insurance are markedly less likely to be dispensed 90-day fills, a modifiable barrier to improving adherence.