Temporal trends and patient determinants of geographical variation in oral anticoagulant treatment of atrial fibrillation: a Danish nationwide cohort study in 2013-2022.

OBJECTIVES

To investigate temporal trends in the geographical variation in oral anticoagulant (OAC) treatment of patients with atrial fibrillation, to evaluate the extent to which regional differences in patient populations may explain this difference and to explore whether patient predictors of adherence may have a different impact across regions.

DESIGN

Register-based cohort study from 1 January 2013 to 31 December 2022.

SETTING

The study used data from nationwide health registers to explore differences in OAC adherence across the five administrative regions in Denmark.

PARTICIPANTS

Patients with atrial fibrillation and a CHADS-VASc score ≥2 (n=291 666).

OUTCOME

Population adherence to OAC treatment operationalised as the proportion of days covered (PDC).

RESULTS

A continuous rise in overall adherence (PDC) from 53% to 78% was observed during the study period. Concurrently, the predominant treatment shifted from vitamin K antagonists to direct OACs with a preference for rivaroxaban and apixaban. The adherence variation between the highest-performing and lowest-performing regions decreased from 18% in 2013 to 9% in 2022, whereas the relative between-regions rankings remained unchanged. Applying multivariate Poisson models adjusting for patient demographics, health status and socioeconomic factors did not substantially change the inter-regional variations; this suggests that different compositions of patient populations cannot explain these variations. However, the impact of socioeconomic factors and comorbidities among patients was unequal across regions. In regions with the lowest overall adherence, a higher risk of non-adherence was seen among patients having mental health disorders, low income and living alone.

CONCLUSIONS

The geographical variation in OAC adherence decreased over time as the overall adherence improved. However, substantial variation remained.