Thesis

Oral anticoagulant prescribing in Scotland, 2010–2020 : a population-based multi-study analysis

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Awarding institution
  • University of Strathclyde
Date of award
  • 2026
Thesis identifier
  • T18012
Person Identifier (Local)
  • 202276209
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Abstract
  • Introduction: Direct oral anticoagulants (DOACs) have largely replaced vitamin K antagonists (VKAs) such as warfarin for the prevention and treatment of thromboembolic disorders. Despite guideline recommendations for DOACs as firstline therapy, uncertainty remains regarding optimal agent selection in routine practice, particularly among patients with complex comorbidities, renal impairment, or varying risk profiles. Real-world prescribing may also be influenced by non-clinical factors and external pressures such as the COVID-19 pandemic. Methods: This thesis comprised complementary studies using linked, populationbased healthcare data from Scotland. A scoping review (2010–2023) identified factors influencing anticoagulant prescribing choice. Retrospective cohort analyses examined trends in oral anticoagulant (OAC) prescribing between 2010 and 2020, stratified by age, sex, and geographic region. The impact of the COVID-19 pandemic on OAC initiation, prevalence, and switching from VKAs to DOACs was assessed using time-series and segmented regression analyses (2018–2021). Factors associated with switching were evaluated using Cox regression models, and clinical outcomes following switching were analysed using time-to-event and survival methods. Additional analyses explored the role of renal function in anticoagulant selection among incident OAC users. Results: The scoping review identified anticoagulant choice as multifactorial, influenced by demographic factors such as age and sex, and clinical factors including renal impairment, prior stroke, heart failure, and thromboembolic risk. OAC initiation increased 72% between 2011 and 2019, followed by a modest decline in 2020. DOACs progressively replaced VKAs, accounting for over 90% of new OAC initiations by 2020. Early variation in prescribing by age group and geographic region diminished over time. Apixaban and edoxaban became most commonly prescribed. COVID-19 pandemic was associated with a temporary reduction in incident OAC prescribing and a marked increase in switching from warfarin to DOACs. Switching was associated with lower rates of intracranial haemorrhage, but higher rates of ischaemic stroke, myocardial infarction, and mortality compared with continued warfarin use. DOAC prescribing increased across all levels of renal function, with apixaban most commonly used among patients with impaired kidney function. Conclusion: OAC prescribing in Scotland underwent substantial transformation between 2010 and 2020, driven by evolving evidence, guidelines, and external pressures. COVID-19 accelerated this transition, revealing how external factors can rapidly reshape prescribing practices.
Advisor / supervisor
  • Mueller, Tanja
  • Kurdi, Amanj
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DOI

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