Summary
Dr. Chapa reviews a new expert review from AJOG MFM (November 2024) arguing that 162 mg aspirin is superior to 81 mg for preeclampsia prophylaxis. He traces the accumulating evidence from Stephanie Roberge's 2017 meta-analysis through the 2023 Henry Ford retrospective studies and the 2024 ASPREO trial, all pointing toward a dose-response effect favoring higher aspirin doses. A key finding is that 162 mg significantly reduces preeclampsia rates in high-risk patients without increasing bleeding complications. However, one caveat emerges: in women with chronic hypertension specifically, even 162 mg may not be effective, suggesting a different underlying pathophysiology. Chapa also discusses the limited clinical utility of current preeclampsia screening biomarker tests despite FDA clearance, citing a publication from George Saad and Baha Sibai.
Key Points
- A November 2024 expert review in AJOG MFM argues for moving from 81 mg to 162 mg aspirin for preeclampsia prophylaxis
- The 2017 Roberge meta-analysis of 45 RCTs showed a dose-response effect with greatest risk reduction above 100 mg
- Henry Ford retrospective study found 162 mg significantly reduced preeclampsia in high-risk patients with no increase in bleeding complications
- The 2024 ASPREO trial showed 78% certainty that 162 mg outperforms 81 mg in reducing severe preeclampsia in high-risk obese patients
- In women with chronic hypertension, neither 81 mg nor 162 mg showed benefit, suggesting a separate pathophysiology
- Higher-dose aspirin (>100 mg) started before 16 weeks may actually decrease placental abruption risk rather than increase it
- FDA-cleared preeclampsia biomarker screening tests lack proven clinical utility according to leading researchers
Key Moments
The Dose Controversy - 81 mg vs 162 mg Aspirin
Dr. Chapa lays out the central controversy around aspirin dosing for preeclampsia prevention, noting that while ACOG still endorses 81 mg, evidence increasingly favors 162 mg.
"Should it be universal? Should we still stick with a risk-based approach? And the biggest controversy of all, of course, is the dose. Is it 81 milligrams? Should it be 150? Should it be double two baby aspirins in the U.S.? In other words, taking two 81 milligrams or 162?"
162 mg Reduces Preeclampsia Without Increased Bleeding
The Henry Ford study found significantly lower preeclampsia rates with 162 mg aspirin and crucially no increase in bleeding complications at the higher dose.
"a significantly lower rate of preeclampsia in high-risk patients who were treated with 162 milligram dose of aspirin for preeclampsia prophylaxis with bleeding complications that were not seen at the higher dose"
Chronic Hypertension - Where Even 162 mg May Not Work
A retrospective study from Henry Ford found no difference in superimposed preeclampsia rates between no aspirin, 81 mg, and 162 mg in women with chronic hypertension, suggesting a separate etiology.
"there were no differences in the incidence of superimposed preeclampsia between the three groups"
ASPREO Trial - 78% Certainty 162 mg Outperforms 81 mg
The 2024 ASPREO randomized trial from UT Houston found 78% certainty that 162 mg aspirin reduces severe preeclampsia compared to 81 mg in high-risk obese individuals.
"this trial suggests that a 78% certainty that 162 mg aspirins compared to 81 mg decreases preeclampsia with severe features. This trial supports doing a larger Phase 3 multi-center trial"
