(419) Sociodemographic differences in perinatal outcomes following publication of the CHAP trial

Thursday, January 30, 2025

4:00 PM – 6:00 PM

Submitting Author and Presenting Author(s)

Anthony E. Melendez Torres, MD (he/him/his)

Clinical Fellow
Duke University School of Medicine
Durham, North Carolina, United States

Coauthor(s)

Sarah K. Dotters-Katz, MD

Associate Professor
Duke University School of Medicine
Durham, North Carolina, United States
Sarahn M. Wheeler, MD

Associate Professor of Obstetrics and Gynecology
Duke University School of Medicine
Durham, North Carolina, United States
Rachel L. Wood, MD (she/her/hers)

Assistant Professor
Duke University
Durham, North Carolina, United States

Objective: The April 2022 CHAP trial showed that tight chronic hypertension (cHTN) control decreased preterm birth (PTB) and low birthweight (BW) < 2500g. We conducted a difference in differences (DID) analysis to assess population-level sociodemographic disparities in these outcomes before and after publication and dissemination of the CHAP trial.

Study Design: Population level DID analysis from February 2021 to August 2023 using US Natality data including patients with a singleton, non-anomalous gestation, cHTN, and who initiated prenatal care at < 6 months gestation. Pre- and post-CHAP periods were defined a priori as February 2021-January 2022 and September 2022-August 2023 respectively with a dissemination period from February-August 2022. Primary outcomes were PTB< 35 weeks, PTB< 37 weeks, and BW< 2500g. Differences in outcomes were compared between Black and White race, Hispanic and non-Hispanic ethnicity, and privately and publicly insured patients during pre- and post-CHAP trial periods. The difference in differences was then calculated. Average treatment effect differences were obtained using linear regression with Stata18 SE.

Results: Black, Hispanic, and publicly insured patients had higher rates of PTB and low BW during the study period compared to their White, non-Hispanic, and privately insured counterparts (Table 1). Rate differences between subgroup categories were significant during the pre- and post-CHAP periods for PTB< 35 weeks, PTB< 37 weeks, and BW< 2500g, except for BW< 2500g during the pre-CHAP period in the ethnicity subgroup. Treatment effect differences in differences were not significant for any primary outcome across subgroups (Table 1).

Conclusion: Sociodemographic disparities in PTB and low BW in patients with cHTN were identified across racial, ethnic, and payor status subgroups both prior to and after the CHAP trial. However, existing disparities were unchanged by dissemination of CHAP trial. Future research should assess in more granular detail if application of CHAP trial interventions can improve these disparities.