Primary and secondary adherence to antihypertensive medications during pregnancy and postpartum

Abstract

Objective: To examine adherence to antihypertensive medications during pregnancy and postpartum among patients with hypertensive disorders of pregnancy (HDP)..

Study design: Using electronic health records and healthcare claims data, we examined prenatal care patients aged 16-49 years from a health care system in Minnesota who delivered between 2009-2021, had continuous medical and pharmacy insurance coverage throughout pregnancy and up to 6 weeks postpartum, and had HDP (pre-existing/gestational hypertension, preeclampsia, HELLP syndrome, and eclampsia).

Main outcome measures: Primary outcome was primary adherence to antihypertensives during pregnancy and up to 6 weeks postpartum, separately, defined as filling of first outpatient prescription within 7 days. Secondary outcome was secondary adherence during pregnancy among patients with pre-existing hypertension, defined as proportion of days covered, calculated using prescription fill data. We estimated risk ratios (RR) and 95 % confidence intervals (CIs) to assess associations between patient characteristics and adherence.

Results: Among 4,647 eligible patients, 526 (11.3%) and 987 (21.2%) had an outpatient antihypertensive prescription during pregnancy and postpartum, respectively. Primary adherence was observed for 72.6% patients during pregnancy and 73.4% during postpartum. Patients with Black versus White healthcare provider at their first prenatal visit were more likely to have primary adherence during pregnancy (RR 1.22, 95% CI 1.03-1.46) while severe blood pressure was associated with adherence during postpartum (RR 1.26, 95% CI 1.14-1.40). Secondary adherence during pregnancy was 63.6%. Patient race, obesity, health insurance type, and parity were associated with secondary adherence.

Conclusion: Approximately 70% of eligible patients had primary adherence but secondary adherence was lower for antihypertensive treatment during pregnancy.

Keywords: Antihypertensive; Drug utilization; Hypertension in pregnancy; Medication adherence; Preeclampsia; Pregnancy complications.