122 Are We Effective Prescribers? A Retrospective Audit of DOAC Prescribing Post Embolic Stroke for Non Valvular Atrial Fibrillation

Abstract Background Direct oral anticoagulants (DOAC) are indicated for stroke prophylaxis in non-valvular atrial fibrillation, which is responsible for up to 20% of all ischaemic strokes(1). We performed a retrospective audit of all consecutive stroke patients in an Irish teaching hospital over a 1-year period to investigate the rate of incorrect dosing and any risk factors for this occurring. Methods We assessed our hospital stroke database from January to December 2017. Our research focused on DOAC prescribing in non valvular atrial fibrillation post embolic stroke. We collected data on baseline characteristics, choice of anticoagulation, dosing, and assessment of renal function, with follow up renal function if available. We reviewed electronic discharge summaries, online laboratory systems and completed a chart review. Results There was a total of 116 people with atrial fibrillation who developed an embolic stroke in our centre, of which 68 were eligible for anticoagulation using a DOAC (59). The main reasons for omission were CKD and haemorrhagic transformation. Patients were discharged on either Apixaban (32 patients), Rivaroxoban (32 patients), or Dabigatran (4 patients). Following our review, we established that 54/68 (79%) of patients were correctly anticoagulated. Over 20% of patients were incorrectly dosed and there was a clear tendency to under-dose 13/14 (93%). There were significant differences between the correct and incorrect dosing groups, with the latter group of patients being older and more at risk of polypharmacy. Renal function did not differ significantly between the groups at discharge or follow up and none of the incorrectly dosed patients were on a concurrent anti platelet. Conclusion A significant number of patients prescribed DOAC in hospital were not appropriately anticoagulated (21%), a majority of which were under-dosed. The patients who were under-dosed were older and more likely to be on 5 or more medications.