Daily Dose: Aspirin Discontinuation & Preeclampsia in High-risk Patients

Patient Care brings primary care clinicians a lot of medical news every day—it’s easy to miss an important study. The Daily Dose provides a concise summary of one of the website's leading stories you may not have seen.

On February 22, 2023, we reported on a study published in JAMA that examined whether aspirin discontinuation in pregnant individuals with normal soluble fms-like tyrosine kinase–1 to placental growth factor (sFlt-1:PlGF) ratio between 24 and 28 weeks of gestation was noninferior to aspirin continuation to prevent preterm preeclampsia.

The study

The study was conducted at 9 maternity hospitals across Spain and enrolled patients who werepregnant, aged >18 years, carrying a singleton fetus with a gestational age between 24 and 28 weeks. Participants were required to be at high risk (>1/170) of developing preeclampsia, and to have initiated aspirin therapy (150mg daily) before 16 weeks, 6 days of gestation. Finally, to be eligible for the final analysis, patients had to have an sFlt-1:PlGF ≤38 (low) during the study period. Between 24 and 28 weeks of gestation, participants were randomly assigned, in a 1:1 ratio, to either continue aspirin treatment (control group) or discontinue aspirin treatment (intervention group). From the time of randomization up to gestation week 36, patients attended study visits every 4 weeks and then every week subsequently until delivery.

The final cohort with available data for primary and secondary outcomes numbered 936 (473 randomized to discontinue aspirin, 463 to continue aspirin). Participant’s mean age was 32.4 years; 3.4% were Black and 93% were White. There were 7 cases of preterm preeclampsia among the 473 pregnant participants (1.48%) in the intervention group and among 8 of 463 pregnant participants (1.73%) in the control group (absolute difference, −0.25% [95% CI, −1.86% to 1.36%]). The median gestational age of delivery for cases of preterm preeclampsia in both the intervention and control groups was 35.1 weeks (P=.42). The researchers report observing no significant differences between the groups in the rates of most adverse events at delivery. At least 1 bleeding complication occurred in 8% of patients in the intervention group and 12.7% of patients in the control group, suggesting that discontinuation of aspirin could potentially reduce the risk of minor bleeding complications at ≥37 weeks of gestation. Investigators emphasize the main strength of the work, the first of its kind, is the novelty of the evidence that suggests continuation of aspirin therapy in pregnant persons at high risk of preterm preeclampsia until 36 weeks of gestation may not be necessary in all cases.

Note from authors

"Aspirin discontinuation at 24 to 28 weeks of gestation was noninferior to aspirin continuation for preventing preterm preeclampsia in pregnant individuals at high risk of preeclampsia and a normal sFlt-1:PlGF ratio."

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