Appendices for "Systemic Health Intervention Design through Participatory Modeling: Low-dose Aspirin for Women at Risk of Preeclampsia"

Preeclampsia (PE) and eclampsia accounted for 7% of maternal mortality in the United States (2016 – 2018). In California, in-hospital diagnosed PE rates rose from 4.6% to 8.1% (2017-2023), with severe cases increasing from 2% to 4% and mild-to-moderate cases from 1% to 2.7%. Clinical guidelines recommend a daily low-dose aspirin (LDA) regimen of 81 mg starting at 12 weeks’ gestation for at-risk women. However, uptake rates vary significantly, ranging from 47% to 79%. The complexity of decision-making around LDA use underscores the need for systemic intervention. This paper presents our approach to identifying system boundaries and designing a systemic intervention to improve LDA uptake among at-risk women, using knowledge synthesis, focus groups, and community-participatory modeling. We collaborated with healthcare providers in Riverside, California, who contributed contextual insights during group model building (GMB) workshops. Using a system dynamics simulation model, we conducted scenario analyses to identify leverage points and optimize the number of women initiating LDA (referred to as “Stock”). Simulation results identified six key drivers of increased LDA uptake: (1) frequency of women’s interpersonal contacts, (2) dissemination of information by authoritative organizations online, (3) time required for nurse training on LDA protocols, (4) timing of enrollment in home visiting programs, (5) capacity of trained home visitors, and (6) awareness of home visiting programs among pregnant women. Model optimization suggests that targeting these variables could increase cumulative LDA uptake by 63% over 120 months.