Impact of aspirin 162mg on the prevention of superimposed preeclampsia in women with chronic hypertension

The aim of this study is to examine the efficacy of aspirin 162 mg vs 81 mg vs no aspirin in the prevention of superimposed preeclampsia among women with chronic hypertension. A retrospective chart review was performed at Henry Ford Health, HFH, between 2013 and 2020. Inclusion was made for all women with a diagnosis of chronic hypertension while pregnant. Three groups were identified: the ‘no aspirin’ group composed of women who were not taking aspirin during their pregnancy, and the ‘aspirin 81 mg’ and the ‘aspirin 162 mg’ groups composed of women taking aspirin 81 mg and aspirin 162 mg respectively during their pregnancies. A total of 1135 women were diagnosed with chronic hypertension: 465 women were not on aspirin prophylaxis, 459 women were on aspirin 81mg, and 211 women were on aspirin 162mg. Maternal demographics were not significantly different. Superimposed preeclampsia was diagnosed in 144 women (31.0%) in the ‘no aspirin’ group, compared to 163 (35.5%) in the ‘aspirin 81 mg’ group, and 66 (31.3%) in the ‘aspirin 162 mg’ group. There was no difference in the incidence of superimposed preeclampsia between the three groups (p=0.293). There was also no significant difference in incidence of superimposed preeclampsia when performing subgroup analysis based on chronic hypertension and concurrent: history of preeclampsia (p=0.407), BMI >30 kg/mˆ2 (p=0.894), or pregestational diabetes (p=0.0947). Our results support findings in the literature which report that low dose aspirin of 81 mg is not sufficient to prevent superimposed preeclampsia among women with chronic hypertension. We here also showed that the higher dose of 162 mg is also not sufficient. This suggests a possible separate etiology for preeclampsia among this particular patient population.