(793) Maternal risk factors for preeclampsia and prescription practices of low dose aspirin for preeclampsia prophylaxis.

Objective: To determine how prophylactic low dose aspirin (LDA) prescription rates differed across different maternal risk factors for preeclampsia.

Study Design: Retrospective study of patients that met SMFM criteria to initiate LDA ppx who received prenatal care and delivered at a single academic center between January - May 2021. Exclusion criteria: age < 18 years old, transfer of care >28 weeks, and delivery < 20 weeks gestation. Patient characteristics, moderate risk (MR) and high risk (HR) criteria, and pregnancy outcomes were collected. Rate of aspirin prescription across different MR and HR factors for preeclampsia groups were compared. Statistical analysis was performed using Chi square and univariate analysis with significance defined as p < 0.05.

Results: Of the 622 patients who were included in the study, 60.3% of patients met criteria to initiate LDA prophylaxis with either 2 MR factors or at least 1 HR factor. Risk factors that were more likely to be prescribed LDA were a history of preeclampsia, chronic hypertension, pregestational diabetes, autoimmune disease, and APLS (Table 1). 82 patients (67.8%) with 1 high risk factor were prescribed LDA, compared to only 13.8% (n=35) of patients with 2 moderate risk factors (OR 13.15, 95% CI 7.8-22.2). When comparing patients with 2 or more high risk factors to patients with 1 high risk factor or 2 moderate risk factors only, providers prescribed LDA at a rate of 92.3% vs. 29.0% (OR 29.4, 95% CI 3.8-228.7), respectively. Risk factors with no significant differences in rates of LDA prescription included obesity (BMI >30), class III obesity (BMI >40), kidney disease, cardiac disease, gestational diabetes, thrombophilia, obstructive sleep apnea, hypothyroidism, AMA, and interpregnancy interval >10 years.

Conclusion: Patients with 2 or more high risk factors for preeclampsia were more likely to be appropriately prescribed LDA than patients with only 1 high risk factor or only moderate risk factors.