Introduction Warfarin has long been the mainstay of treatment and prevention of arterial and venous thromboembolism. Recently, novel oral anticoagulants (NOACs) have been approved for the prevention of arterial thromboembolism in non-valvular atrial fibrillation and treatment of venous thromboembolism. They have become a popular and effective alternative to warfarin and so it is ever more important to assess our current practice with regards to anticoagulation. We sought to describe the current cohort of patients receiving warfarin therapy and assess suitability for NOACs.

Methods This was a prospective observational study performed over a six month period at a university teaching hospital. Informed consent was obtained from each patient attending the warfarin clinic. Ethical approval was obtained from the local ethics board. A standard questionnaire was used in combination with a patient chart and laboratory data review. Data were collected in Excel spreadsheet format and SPSS© was used for statistical analysis. We performed a stepwise exclusion based on renal function (eGFR MDRD) in order to ascertain who would be suitable for potential switch to a NOAC. Data are presented as mean +- SD unless otherwise stated.

Results Of a total of 526 patients, 219 (41.6%) were female and 307 (58.4%) were male. The mean age was 67.6 ± 14.7 years. The indication for anticoagulation was non-valvular atrial fibrillation (NVAF) in 303 (57.6%) patients and venous thromboembolism in 131 (24.9%). There was an indefinite intended duration in 486 (92.4%). Median CHADSVASC score was 3. Median HASBLED score was 2. There were 459 (87%) patients with eGFR >50 ml/min/1.73 m². Only 14 (2.66%) of patients had eGFR <30 m/min/1.73 m² (CKD Stage 4). Of the 303 patients with NVAF, only 8 (2.6%) had CKD Stage 4 or worse. 2 (1.5%) of VTE patients had CKD Stage 4.

Conclusion Based on this subset analysis of the data from our observational study. Of our cohort, 80.6% were suitable for consideration of switching to a NOAC. This does not include a small number of patients with CKD Stage 4 in whom cautious use of reduced dose NOAC may be considered. Further analysis of the overall health economics is warranted on the basis of these results.