(A20) Social and Demographic Disparities in the Adherence to Antihypertensive Medication During Pregnancy

Publication Number: 303

Background: Chronic hypertension is a risk factor for multiple adverse pregnancy outcomes. The Chronic Hypertension and Pregnancy trial demonstrated better outcomes in pregnant individuals with antihypertensive treatment (AHT) for mild chronic hypertension compared with expectant management. However, AHT adherence in routine care may be suboptimal and influenced by patient characteristics.

Objectives: To identify associations between race and socio-demographic characteristics and AHT adherence during pregnancy among AHT initiators.

Methods: In a nationwide cohort of publicly insured pregnancies 2000-2018 linked to US census data, we identified individuals who initiated AHT with methyldopa or labetalol, the most commonly prescribed antihypertensives in pregnancy, during the first half of pregnancy. Patient characteristics – including socio-demographic factors, concomitant medication use, adequacy of prenatal care, and comorbidities – were assessed and differences by race/ethnicity evaluated. Treatment adherence was defined as having a proportion of days covered (PDC) of ≥80% during the second half of pregnancy. Generalized linear models were used to assess discrepancies in adherence by race/ethnicity, while controlling for other patient characteristics.

Results: Among the 14,240 AHT initiators, 43.8% were Black, 31.5% White, 17.9% Hispanic, and 6.8% of other race/ethnicity. Black individuals were more likely to live in areas with higher poverty and unemployment, to be from the South, to have less adequate prenatal care and higher comorbidity scores as compared to White individuals. Differences were similar, yet less pronounced for Hispanic vs. White individuals. The proportion of individuals who adhered to treatment (N=3,458) was substantially lower for Black individuals (17.1%) as compared to the other race/ethnicity groups (range: 29.6-30.6%), leading to 43% reduced adherence on the relative scale and 12.7% on the absolute scale in Black vs. White individuals (Relative risk [RR]=0.57, 95% CI: 0.53-0.62]; risk difference [RD]=-12.7%, -14.4%--11.1%). The association remained after accounting for other patient characteristics (adjusted RR=0.58, 0.54-0.63; adjusted RD=-10.4%, -12.5%--8.3%). Other factors strongly associated with low adherence were older age, less adequate prenatal care, and higher comorbidity scores.

Conclusions: Our findings emphasize that treatment adherence differs by race/ethnicity, which remained consistent after accounting for socio-demographic and clinical characteristics. Since chronic hypertension during pregnancy affects more Black individuals, strategies to improve hypertensive management are urgently needed to reduce preventable adverse pregnancy outcomes and reduce racial disparities.