(263) Aspirin Prescribing and Adherence Patterns for Pregnant Patients in a Safety-Net System

To review gestational ages at which aspirin (ASA) was prescribed and adherence patterns for patients at moderate and high risk for preeclampsia in a safety-net system, to inform future implementation strategies where this patient population is often at increased risk for preeclampsia.

Study Design:

We conducted a retrospective cohort study of 921 deliveries at-risk for preeclampsia from January to November 2024 of three safety-net hospitals in California. Among the 537 at-risk patients who received ASA during pregnancy, maternal demographics, clinical and delivery data, medication reconciliation data of self-reported adherence for ASA, and adherence through pregnancy to delivery were extracted. Descriptive statistics were used to compare medical and social characteristics with preeclampsia outcomes. A multinomial logistic regression model was used to assess the association between ASA adherence (low, moderate, high), timing of prescription, and preeclampsia risk. An interaction term was included to analyze if preeclampsia risk varied by prescription timing in each adherence group.

Results:

59% of those prescribed ASA were high risk with multiple moderate risk factors: Hispanic (64%) or Black (23%), publicly insured (93%) and BMI >30 (76%). There was a significant interaction between timing and adherence, p=0.03. High adherence was more common when aspirin was prescribed < 12 weeks (68.7%) than at 12–16 weeks (41.5%). Compared to high adherence, preeclampsia risk was higher in the low (aOR=4.53, 95% CI: 2.61–7.93) and moderate (aOR=3.32, 95% CI: 1.86–5.95) adherence groups.

Conclusion:

In safety-net hospitals where most patients are high risk for preeclampsia, high adherence to ASA (≥ 75% of self-reported adherence) during pregnancy significantly reduces preeclampsia risk. Adherence improves when patients are prescribed ASA between 12-16 weeks compared to > 16 weeks, with the best adherence seen when prescribed < 12 weeks. Implementation strategies such as early prescription and early tailored counseling should be prioritized in safety-net settings to improve adherence and lower prescribing barriers.