Sex-Based Disparities in Health Care Access and Utilization Among Patients With Atrial Fibrillation.

Importance: Females with atrial fibrillation (AF) experience a higher risk of stroke, myocardial infarction, and mortality than males with AF. Theories suggest that sex-based differences in hormonal, structural, and electrophysiologic factors are associated with this imbalance; we hypothesized that sex-based differences in health care access and utilization (HCAU) are also underlying factors. Objective: To determine whether sex-based disparities in HCAU barriers exist among individuals with AF. Design, Setting, and Participants: This cross-sectional study used data on patients with AF in the All of Us Research Program Registered Tier dataset (version 8), which contains integrated data from the electronic health record and various health surveys between August 8, 2016, and October 1, 2023. Inclusion criteria were age 18 years or older, a SNOMED (Systematized Nomenclature of Medicine) diagnosis of AF, and completion of the Health Care Access and Utilization Survey. Exclusion criteria included lack of binary sex information. Data were extracted and analyzed between November 2025 and April 2026. Main Outcomes and Measures: Association between sex at birth and participant responses to 20 HCAU outcomes. Multivariable logistic regression and marginal standardization were used to calculate unadjusted and adjusted odds ratios, adjusted predicted probabilities (APPs), and adjusted risk differences (ARDs). Multiplicity was addressed using the Holm-Bonferroni method. Results: The 12 428 eligible participants had a median (IQR) age of 70 (63-75) years and included 6877 males (55.3%). Compared with males with AF, females with AF had significantly higher APPs of reporting HCAU barriers to 14 of 20 outcomes after adjusting for baseline differences in sociodemographic and clinical characteristics. The largest differences were observed in cost-related medication access and adherence behaviors and nervousness about seeing a health care practitioner. Females compared with males were more likely to report asking for a lower-cost medication (APP, 25.12% [95% CI, 23.92%-26.32%] vs 20.84% [95% CI, 19.82%-21.86%]; ARD, 4.28 [95% CI, 2.65-5.90] percentage points), being unable to afford prescription medications (APP, 12.77% [95% CI, 11.93%-13.61%] vs 9.20% [95% CI, 8.47%-9.93%]; ARD, 3.57 [95% CI, 2.42-4.72] percentage points), delaying prescription fills (APP, 11.20% [95% CI, 10.38%-12.01%] vs 7.81% [95% CI, 7.12%-8.50%]; ARD, 3.39 [95% CI, 2.29-4.48] percentage points), and being nervous about seeing a health care practitioner (APP, 9.35% [95% CI, 8.57%-10.14%] vs 6.18% [95% CI, 5.56%-6.80%]; ARD, 3.17 [95% CI, 2.14-4.21] percentage points). Conclusions and Relevance: In this cross-sectional study, females with AF reported a greater burden of HCAU barriers than males with AF. This finding may explain some of the observed differences in AF outcomes between sexes.