Atrial fibrillation (AF) is the most common heart arrhythmia disorder in the world, and the condition is associated with a five-fold increased risk of haemorrhagic stroke. Anticoagulants can reduce the risk, but epidemiological studies have shown that many patients do not receive the treatment. This suggests a gap between research-based knowledge and daily clinical practice.

Anticoagulant decisions are, however, complicated, and the pros and cons must be carefully weighed. Many patients with atrial fibrillation (AF) are followed by their general practitioner (GP), but we do not know the reasons for this apparent undertreatment and what role general practice plays.

This PhD project aimed to create a knowledge base to support the development of an intervention to ensure appropriate anticoagulation treatment for patients with AF.

Two objectives, three studies

The first objective was to investigate variation in anticoagulant prescribing patterns across general practice clinics and the five Danish regions. Variation may indicate deviations from guideline-based treatment and point to possible areas for improvement. The second objective was to investigate why some patients with AF do not take anticoagulants.

Two population-based cohort studies, based on data from Danish national health registries, investigated treatment variation, whereas an audit study, based on a review of patient records from general practice, explored the reasons for non-treatment.

Although anticoagulant treatment has increased over the past decade, the registry studies showed that a fifth of patients with AF do not receive treatment. Yet, there was virtually no variation in prescription patterns between clinics.

Active choice based on clinical considerations

The review of medical records (the audit study) for patients receiving no anticoagulants for AF showed that this, in the vast majority of cases, was an active choice based on clinically relevant considerations. This finding was surprising.

'We expected the studies to provide background knowledge for developing a targeted intervention in general practice to ensure appropriate anticoagulant treatment for patients with AF. Instead, the results indicate that the incidence of clinically relevant undertreatment is low although up to one fifth of patients with AF receive no treatment,' says Ina Grønkjær Laugesen.

She emphasises that there is still room for improvement in selected patient groups.

'Future research should investigate how follow-up pathways can be optimised to ensure timely identification of treatment needs, without burdening patients and the healthcare sector with unnecessary interventions,' she says.

Oral defence on 30 April 2025

Ina Grønkjær Laugesen will defend her PhD dissertation “Anticoagulant therapy for atrial fibrillation: exploring the treatment gap among patients in general practice” on Wednesday 30 April 2025 at 14:00 in the auditorium (room 201) at Aarhus Institute of Advanced Studies (AIAS), building 1632, Aarhus University, Høegh-Guldbergs Gade 6B, 8000 Aarhus C.

The defence is public. Everyone is welcome. After the defence, the Research Unit for General Practice will host a small reception in room 118, building 1261, at the Department of Public Health, Aarhus University.

About the project

The PhD dissertation and the three included scientific papers present the results of a three-year enrolment at the Graduate School of Health, Aarhus University. The project was conducted in close collaboration between the Research Unit for General Practice and the Department of Public Health at Aarhus University.

The project was supported by grants from Aarhus Graduate School of Health, the Foundation for Primary Health Care Research, the Danish Foundation for General Practice, the Committee for Quality Improvement and Continuing Medical Education in the Central Denmark Region.

Further information

PhD student Ina Grønkjær Laugesen
Aarhus University, Department of Public Health &
Research Unit for General Practice
inalauge@ph.au.dk

The 3 studies of the project

• General practice-related variation in oral anticoagulant treatment of atrial fibrillation: a nationwide cohort study. Laugesen IG, Vestergaard CH, Paust A et al. BJGP Open. 2025 Nov 11:BJGPO.2024.0197. doi: 10.3399/BJGPO.2024.019.
• Temporal trends and patient determinants of geographic variation in oral anticoagulant treatment of atrial fibrillation: a nationwide cohort study in 2013-2022. Laugesen IG, Prior A, Mygind A et al. Accepted for publication in BMJ Open.
• Anticoagulant treatment omission in patients with atrial fibrillation: an audit of patient records in general practice. Laugesen IG, Mygind A, Grove EL et al. Accepted for publication in BMC Primary Care.