Dosing accuracy of direct oral anticoagulants: the effect of an educational intervention

Abstract

The prescription rates of direct oral anticoagulants (DOACs) have steadily increased since their introduction as an alternative to warfarin.1,2 The reduced reliance on laboratory monitoring demands greater responsibility from the clinician to accurately dose these anticoagulants based on patient characteristics. One Australian study suggests the prescriptions of up to one-third of patients on DOACs may be inappropriate.3 We sought to study the effect of a targeted educational intervention on the accuracy of DOAC prescriptions at a 621-bed tertiary teaching hospital. All inpatients prescribed a DOAC on discharge were identified from electronic hospital records. These records were reviewed and data on patient demographics, weight, serum creatinine, indication and prescribed dose of DOAC were extracted. The appropriate dose was determined using Product Information documents from the Therapeutic Goods Administration, based on varying factors for each agent including indication, age, weight, serum creatinine and creatinine clearance as calculated by the Cockcroft-Gault equation. Pre-intervention data were collected from March to June 2016, followed by an educational campaign. This consisted of a survey distributed to all residents and awareness raising sessions with interns and ward pharmacists. Post-intervention DOAC dosing accuracy data were then collected for the months August to November 2016. 316 patients in the pre-intervention group and 453 patients in the post-intervention group were identified. 79 and 77 patients were excluded from their respective groups, due to insufficient data to ascertain the appropriate dose. A total of 237 patients in the pre-intervention group and 376 patients in the post-intervention periods were included for analysis. Baseline characteristics were comparable for age and creatinine clearance between the groups, but not male gender (45.6% vs 55.6%, P = 0.02). 26.6% of the patients were prescribed incorrect doses in the pre-intervention group compared with 22.1% in the post-intervention group (P = 0.202). In the post-intervention group, a significantly higher proportion of patients newly commenced on DOACs were dosed appropriately compared with those on existing DOAC prescriptions (85% vs 72%, P < 0.05). Around 1 in 4 patients on DOACs were either under- or over-dosed. There was a small improvement in dosing accuracy after an educational intervention, in particular for those who were started on DOACs whilst inpatient. Ongoing quality improvement initiatives to improve DOAC prescription accuracy are required.