A daily dosage of up to 150 mg of aspirin has a dose-response effect for the prevention

A daily dosage of up to 150 mg of aspirin has a dose-response effect for the prevention of preeclampsia and preeclampsia with preterm birth  (PTB) up to 150 mg daily, a new review in Canada shows.

A certain ongoing uncertainty remains though. A future RCT might compare higher (eg, 150 or 162 mg) vs lower (eg, 81 mg) doses of aspirin in women who exceed a certain risk threshold for the development of preeclampsia.

Aspirin prophylaxis is recommended for women at higher risk of preeclampsia

Yet, there is no consensus about the optimal dose. Moreover, in North America, aspirin is routinely only available in 81 mg and 325 mg tablets. Metaanalyses that use aggregate data pooled from different randomized controlled trials (RCTs) are also more likely to overestimate aspirin’s efficacy compared with those metaanalyses that use individual participant data (IPD).

In the new review, the Canadian team evaluated the efficacy of aspirin at different doses, using IPD from a large metaanalysis of preeclampsia prevention and then compared those findings to that of the recent Aspirin for Evidence-based Preeclampsia Prevention trial (ASPRE). 

The team included 22 primary RCTs

that compared daily aspirin to placebo among 30,532 women at higher risk of preeclampsia. Trials that administered antiplatelet agents other than aspirin were excluded. Evaluated outcomes were (1) preeclampsia (hypertension with new-onset proteinuria ≥20 weeks gestation), (2) preeclampsia with preterm birth (PTB) at <37 weeks gestation.

Results from the review were published in the American Journal of Obstetrics and Gynecology.