Comparing aspirin 75 to 81 mg vs 150 to 162 mg for prevention of preterm preeclampsia: systematic review and meta-analysis

OBJECTIVE:This study aimed to compare 2 aspirin dosage regimens for the prevention of preterm preeclampsia (PE): 75 to 81 mg vs 150 to 162 mg taken daily starting in the first trimester of pregnancy. DATA SOURCES:A systematic search was performed using PubMed, Embase, CINAHL, Web of Science, and Cochrane Central Register of Controlled Trials from January 1985 to April 2023. STUDY ELIGIBILITY CRITERIA:The inclusion criteria were randomized controlled trials that compared the effect of 2 aspirin dosage regimens during pregnancy for the prevention of PE initiated in the first trimester of pregnancy. The intervention was an aspirin dosage between 150 and 162 mg daily, and the control was an aspirin dosage between 75 and 81 mg daily. METHODS:Of note, 2 reviewers independently screened all citations, selected studies, and evaluated the risk of bias. The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and applied the Cochrane risk of bias tool. The corresponding authors of the included studies were contacted to validate each of the collected results. The primary outcome was the risk of preterm preeclampsia, and the secondary outcomes included term preeclampsia, any preeclampsia regardless of gestational age, and severe preeclampsia. Relative risks with their 95% confidence interval were calculated for each study and pooled for global analysis. RESULTS:Of note, 4 randomized controlled trials were retrieved involving 552 participants. Moreover, 2 randomized controlled trials were at unclear risk of bias, 1 trial at low risk of bias and 1 trial at high risk of bias, which did not have the information for the primary outcome. The pooled analysis demonstrated that an aspirin dosage of 150 to 162 mg was associated with a significant reduction of preterm preeclampsia, compared with an aspirin dosage of 75 to 81 mg (3 studies; 472 participants; relative risk, 0.34; 95% confidence interval, 0.15-0.79; P=.01; I2=0%). There was no significant effect on the risk of term preeclampsia (3 studies; 472 participants; relative risk, 0.57; 95% confidence interval, 0.12-2.64; P=.48; I2=64%) and all preeclampsia (4 studies; 552 participants; relative risk, 0.42; 95% confidence interval, 0.17-1.05; P=.06; I2=58%), but there was a reduction of severe preeclampsia (3 studies; 472 participantst; RR, 0.23; 95% CI, 0.09-0.62; P=.003; I2=0%). CONCLUSION:When initiated in the first trimester of pregnancy, an aspirin dosage of 150 to 162 mg daily was associated with a lower risk of preterm PE than an aspirin dosage of 75 to 81 mg daily. However, the lack of large, high-quality studies limited the clinical scope of the current results taken alone.