What is the clinical evidence from this study?

Study design: Cohort. Population: Atrial fibrillation (n=18867). Intervention: Nonwhite race/ethnicity (Asian, Hispanic, Black) vs. White race/ethnicity. Primary outcome: Intracranial hemorrhage (ICH) (HR 4.06, 95% CI 2.47 to 6.65).

June 23, 2026

Racial/Ethnic Differences in the Risk of Intracranial Hemorrhage Among Patients With Atrial Fibrillation

Key Result

Among patients with atrial fibrillation, Asians (HR 4.06; 95% CI 2.47-6.65), Hispanics (HR 2.06), and blacks (HR 2.04) had a significantly higher risk of intracranial hemorrhage compared to whites.

Key Points

This study aims to explore racial/ethnic disparities in the risk of intracranial hemorrhage among patients with atrial fibrillation, focusing on warfarin's impact.
Retrospective identification of a multiethnic cohort with nonrheumatic atrial fibrillation.
Assessment of warfarin use and anticoagulation intensity through pharmacy and laboratory records.
Derivation of crude ICH event rates using Poisson regression and analysis by Cox proportional hazard models.
Identified 18,867 AF hospitalizations with 173 ICH events over 3.3 years.
Hazard ratio for ICH was 4.06 for Asians (95% CI 2.47 to 6.65), 2.06 for Hispanics (95% CI 1.31 to 3.24), and 2.04 for blacks (95% CI 1.25 to 3.35), with whites as the reference.
Warfarin increased ICH risk for all races, with higher magnitude of risk noted among nonwhites.

Study Design

Type

Cohort (n=18,867)

Structured PICO

Does race/ethnicity affect the risk of intracranial hemorrhage in patients with atrial fibrillation treated with warfarin?

Population

18,867 stroke-free patients hospitalized with nonrheumatic atrial fibrillation, followed for 3.3 years.

Exposure

Warfarin therapy

Comparator

White patients (for racial/ethnic comparison)

Outcome

Intracranial hemorrhage (ICH)hard clinical

Nonwhite patients with atrial fibrillation, particularly Asians, have a significantly higher risk of warfarin-related intracranial hemorrhage compared to white patients.

Main Result

Hazard Ratio: 4.06 (95% CI 2.47–6.65)

Abstract

OBJECTIVES: This study was designed to study racial/ethnic differences in the risk for intracranial hemorrhage (ICH) and the effect of warfarin on ICH risk among patients with atrial fibrillation (AF). BACKGROUND: Nonwhites are at greater risk for ICH than whites in the general population. Whether this applies to patients with AF and whether warfarin therapy is associated with comparable risk of ICH in nonwhites are unknown. METHODS: We retrospectively identified a multiethnic stroke-free cohort hospitalized with nonrheumatic AF. Warfarin use and anticoagulation intensity were assessed by searching pharmacy and laboratory records. Crude ICH event rates were calculated by Poisson regression. Cox proportional hazard models were constructed to assess the independent effect of race/ethnicity on ICH after adjusting for age, gender, hypertension, diabetes, heart failure, and warfarin exposure. RESULTS: Between 1995 and 2000, we identified 18,867 qualifying AF hospitalizations (78.5% white, 8% black, 9.5% Hispanic, and 3.9% Asian) and 173 qualifying ICH events over 3.3 years follow-up. Achieved anticoagulation intensity was lower among blacks but not different between the other groups. Warfarin was associated with increased ICH risk in all races, but the magnitude of risk was greater among nonwhites. There were no gender differences. The hazard ratio for ICH with whites as referent was 4.06 for Asians (95% confidence interval CI 2.47 to 6.65), 2.06 for Hispanics (95% CI 1.31 to 3.24), and 2.04 (95% CI 1.25 to 3.35) for blacks. CONCLUSIONS: Nonwhites with AF were at greater risk for warfarin-related ICH. Blacks, Hispanics, and Asians were at successively greater ICH risk than whites.

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