Use of direct oral anticoagulants in Scotland

Student thesis: Doctoral Thesis


Patients with atrial fibrillation (AF), a common arrhythmic disorder, are treated long-term with oral anticoagulants in order to prevent strokes. As warfarin treatment is associated with several problems, the direct oral anticoagulants (DOAC) dabigatran, rivaroxaban, apixaban and edoxaban have been introduced. However, real-world information regarding the utilisation of DOACs as well as their clinical effectiveness and safety is still scarce. Hence, the aim of this project was to increase the evidence from clinical practice regarding the use of DOACs in patients with AF in Scotland. Methods: This study has been designed as a retrospective cohort study (study period 2009 - 2015), using routinely collected administrative data. Three databases - the Prescribing Information System (PIS); Scottish Morbidity records (SMR); and National Records of Scotland (NRS) - covering prescriptions dispensed in primary care, hospital episodes and death records, respectively, have been linked using Community Health Index (CHI) numbers, a unique patient identifier in Scotland. Based on this data, three analyses have been conducted: a description of DOAC prescribing over time; an evaluation of patients' adherence to DOAC treatment; and an analysis of the comparative clinical effectiveness and safety of DOACs. Results: In Scotland, the number of patients being treated with DOACs has steadily been increasing, and in 2015, the number of incident DOAC patients exceeded those of warfarin. During the study period, 14,811 AF patients with a mean age of 74.1 years [SD 11.3] initiated DOAC treatment. Adherence to treatment was good overall, with a median Medication Refill Adherence (MRA) of 102.3% [IQR 90.1% - 112.5%]; discontinuation rates were however variable, ranging from 24.9% (apixaban) to 63.3% (dabigatran). Persistence rates 12 months after treatment initiation were 61.8%, 78.6%, and 83.6% among patients initiating treatment with dabigatran, rivaroxaban, and apixaban, respectively. All DOACs were similarly effective in preventing strokes and systemic embolisms - nevertheless, the overall bleeding risk was higher with rivaroxaban as compared to apixaban [HR 1.52, 95% CI 1.21 - 1.91]. Conclusion: DOACs have swiftly been accepted into clinical practice, and adherence to treatment is generally good. As all DOACs are similarly effective, decisions for or against a specific drug should be made based on a wider risk assessment, with a focus on bleeding risks.
Date of Award15 Dec 2017
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorMarion Bennie (Supervisor) & Blair Johnston (Supervisor)

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