Background: Acute psychological stress has long been recognized as a trigger for cardiovascular events. More recently, attention has turned to sociopolitical stress as a potentially significant cardiovascular risk factor, with United States presidential elections serving as recurring, predictable sources of nationwide psychological stress. The goal of this study was to determine whether US presidential elections are associated with increased rates of acute cardiovascular events.
Methods: This matched control study using difference-in-differences analysis was conducted within the University of California Health System from 2015-2024 using the UC Health Data Warehouse (UCHDW). Participants included adult patients (> or = 18 years) with emergency department or inpatient visits for acute cardiovascular events during study periods. We compared cardiovascular event rates during election risk periods (7 days before to 7 days after election day; 15 days) versus control periods (30 to 14 days before; 17 days) across three presidential elections (2016, 2020, 2024) and five matched control years (2015, 2017, 2019, 2021, 2023). Primary outcomes included hemorrhagic stroke, ischemic stroke, myocardial infarction, life-threatening arrhythmias, and ruptured aneurysms. We calculated event rates per day per year and compared risk versus control periods using chi-square tests and Poisson regression models. Difference-in-difference analysis with interaction terms assessed whether observed associations were election-specific rather than seasonal effects, with statistical significance defined as P< 0.05 and rate ratios considered significant when 95% confidence intervals did not include 1.
Results: Among 63,580 cardiovascular events, hemorrhagic stroke rates (n=3,139) increased by 7.4% during election risk periods (rate ratio [RR]=1.074, 95% CI: 1.001-1.151, P< 0.001), with 33.93 versus 31.61 events per day per year in election and control periods, respectively. Ruptured aneurysm rates (n=1,312) showed a suggestive 8.3% increase (14.24 vs 13.16 events per day per year, P< 0.001), though the confidence interval included unity (RR=1.083, 95% CI: 0.972-1.206). Ischemic stroke rates (n=15,886) decreased by 6.7% during early November (RR=0.933, 95% CI: 0.885-0.984, P< 0.001); however, this pattern was observed in both election and control years. Myocardial infarction rates (n=20,754) and life-threatening arrhythmia rates (n=15,379) remained stable (RR=1.011 and 0.975, respectively; P=0.24 and P=0.02).
Conclusions: Presidential elections are associated with a 7.4% increase in hemorrhagic stroke rates. The observed decrease in ischemic stroke rates during early November appeared to reflect seasonal variation rather than election-specific effects, as it occurred in both election and control years. Study limitations include data from a single health system, calendar-based control periods that may not fully account for seasonal confounding, limited ability to assess individual-level political engagement or stress, and small sample size for ruptured aneurysm that precluded definitive conclusions. Future US-wide studies with larger sample sizes and individual-level stress assessments are needed to confirm these associations and identify high-risk populations who may benefit from targeted preventive interventions during these periods.