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Making a difference: ACOG’s guidance on low-dose aspirin for preventing superimposed preeclampsia

Study results suggest that ACOG’s recommendations for preventing superimposed preeclampsia are having a significant positive impact on outcomes



Investigators at Thomas Jefferson University found that low-dose aspirin therapy in pregnant women with chronic hypertension—as recommended by the American College of Obstetricians and Gynecologists (ACOG) in 20161—was associated with a 57% decrease in superimposed preeclampsia. Chaitra Banala, BS, presented the study’s results in a poster presentation at the ACOG 2018 annual meeting (April 27–30, 2018, Austin, Texas).2

Chaitra Banala, BS (left), and Amanda Roman, MD (right), of Thomas Jefferson University, presenting their study findings at ACOG 2018.

The study’s goal was to evaluate the incidence of superimposed preeclampsia in women with chronic hypertension in the periods before and after the ACOG recommendation was published.

Study participants. Pregnant women with chronic hypertension who delivered at Thomas Jefferson University Hospital from January 2008 to July 2017 were included in this retrospective cohort study. Women with multiple gestations were excluded.

The cohort included 715 pregnant patients with chronic hypertension divided into 2 groups: 635 pre-ACOG patients and 80 post-ACOG patients (that is, patients who delivered before and after the ACOG recommendation). The investigators offered daily low-dose (81 mg) aspirin.

The cohort was further stratified by additional risk factors for superimposed preeclampsia, including a history of preeclampsia and pregestational diabetes.

Outcomes. The primary outcome was the incidence of superimposed preeclampsia. Secondary outcomes included the incidence of superimposed preeclampsia with severe features (SIPSF), small for gestational age, and preterm birth.

Findings. The incidence of superimposed preeclampsia in women with chronic hypertension was 20 (25%) in the post-ACOG group versus 232 (37%) in the pre-ACOG group (odds ratio [OR], 0.43; 95% confidence interval [CI], 0.26–0.73).

In the subgroup of women with chronic hypertension who did not have other risk factors, superimposed preeclampsia and SIPSF were significantly decreased: 4/41 (10%) versus 106/355 (30%) (OR, 0.25 [95% CI, 0.08–0.73]) and 2/41 (5%) versus 65/355 (18%) (OR, 0.22 [95% CI, 0.54–0.97]), respectively. The maternal demographics and secondary outcomes did not differ significantly.

After the ACOG guidance was released, low-dose aspirin decreased superimposed preeclampsia by 57% in all women with chronic hypertension. Of those with chronic hypertension without other risk factors, there were decreases of 75% in superimposed preeclampsia and 78% in SIPSF.

Final thoughts. Ms. Banala said in an interview with OBG Management following her presentation, “When we stratified the cohort based on their risk factors, we found that aspirin had the highest benefit in patients with only chronic hypertension, so without other risk factors. And we found that there was a benefit in patients with chronic hypertension who were not on antihypertensive medication. So overall our study concluded that this guideline has made a significant impact in decreasing the frequency of superimposed preeclampsia.”

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