USA: Preeclampsia, a potentially life-threatening condition characterized by high blood pressure during pregnancy, has long been recognized as a significant risk factor for adverse maternal and fetal outcomes. In a groundbreaking development, a large national cohort study has uncovered preterm preeclampsia as an independent risk factor for thromboembolism, adding a new dimension to the understanding of this complex condition.

Preterm preeclampsia is independently associated with an increased risk of thromboembolic events, the study stated. The study was published online in the American Journal of Obstetrics and Gynecology on May 04, 2024.
Preterm preeclampsia is a product of vascular dysfunction and is associated with prolonged hospital admission and proteinuria, which are significant risk factors for thromboembolism in pregnancy. Thromboembolism risk in preterm preeclampsia warrants further investigation. Therefore, Lara Slesnick, University of Illinois-Chicago, Department of Obstetrics and Gynecology, Chicago, IL, and colleagues aimed to determine the relationship between preterm preeclampsia and thromboembolic risk. They hypothesized that preterm preeclampsia is an independent risk factor for thromboembolism in pregnancy.
For this purpose, the research team conducted a retrospective cohort study using the National Inpatient Sample database via HCUP-AHRQ from 2017-2019. It included all subjects with an ICD-10 code for pregnancy or peripartum encounters. Subjects were excluded if the gestational age at delivery was less than 20 weeks or if they had a history of thromboembolism, antiphospholipid syndrome, or inherited thrombophilia.

Patients with preterm (delivered less than 37 weeks) preeclampsia and term (delivered 37 weeks or greater) preeclampsia were compared to those without preeclampsia. The primary outcome was a composite of any thromboembolic event, including deep vein thrombosis, pulmonary embolism, transient ischemic attack (TIA)/cerebral thrombosis, or other thromboses. The secondary outcomes were rates of each type of thromboembolic event.
The study led to the following findings:
· Of individuals in the database, more than 2.2 million met the inclusion criteria. 2.7% had preterm preeclampsia, and 6.7% had term preeclampsia.
· Those with preterm preeclampsia were more likely to be older, identify as non-Hispanic black, be obese, have chronic hypertension among other chronic diseases, and be in the lowest quartile of income.
· Among patients with preterm preeclampsia, 0.32% experienced thromboembolism, while those with term preeclampsia and without preeclampsia experienced thromboembolism 0.10% and 0.09%, respectively.
· After controlling for confounders that differed between groups, preterm preeclampsia remained independently associated with any thromboembolic event (aOR 2.21) and each type of thromboembolism.
· Term preeclampsia was not associated with an increased risk of thromboembolism (aOR 1.18).
In conclusion, the study's findings underscore the importance of recognizing preterm preeclampsia as an independent risk factor for thromboembolism in pregnant individuals. By integrating these findings into clinical practice and prioritizing research efforts aimed at elucidating the underlying mechanisms, strides can be made toward improving maternal outcomes and enhancing the quality of care for individuals affected by this complex condition.
Reference:
DOI:https://doi.org/10.1016/j.ajog.2024.04.049