East Asian immigration and direct oral anticoagulant dosing for atrial fibrillation: A population-based cohort study

Some East Asian (EA) guidelines recommend lower doses of direct oral anticoagulants (DOACs) for atrial fibrillation (AF) than in North America and Europe.

The study aimed to investigate the association of immigration from EA with DOAC dosing and outcomes in AF.

This was a population-based cohort study using administrative databases of Ontario immigrants with AF aged ≥ 66 years who were dispensed DOAC prescriptions from 2012 to 2019. Birth country was classified as EA or not. We used multivariable logistic regression to assess the association of EA birth with DOAC dose and cause-specific hazards regression for the association of EA birth and DOAC dose with stroke or bleeding or death. The interaction between EA birth and DOAC dosing was studied for each outcome.

Among 14,421 immigrants, 3958 (27.4%) were born in EA. EA immigrants had lower odds of receiving full-dose DOACs vs non-EA immigrants (odds ratio 0.64, 95% confidence interval [CI] 0.58-0.69, P < .001). EA birth was not associated with a composite of hospitalization for stroke or bleeding (hazard ratio [HR] 0.97, 95% CI 0.84-1.12, P = .67) or hospitalization for stroke (HR 0.86, 95% CI 0.71-1.04, P = .13), but was associated with higher bleeding hazard (HR 1.15, 95% CI 1.02-1.30, P = .02) and lower mortality (HR 0.91, 95% CI 0.84-0.99, P = .04). There was no significant interaction between EA birth and DOAC dosing for stroke (P = .41), bleeding (P = .27), or death (P = .33).

EA immigrants were less likely to receive full-dose DOACs and had a higher bleeding hazard, similar stroke hazard, and lower mortality risk than non-EA immigrants. There was no evidence that DOAC dosing had a differential treatment effect in EA immigrants.