Dabigatran Use in Ontario Jumped Over Two Years, Still Far Short of Warfarin

October 16, 2013

KINGSTON, ON — Prescriptions of new oral anticoagulants in Ontario jumped 20-fold over two years starting with the Canadian approval of dabigatran etexilate (Pradaxa, Boehringer Ingelheim) for atrial fibrillation, according to an analysis published today in CMAJ Open[1].

The far greater use of warfarin tapered off proportionately, while prescriptions of rivaroxaban (Xarelto, Bayer Pharma/Janssen Pharmaceuticals), available for less than half the study time, rose only a little.

Dabigatran was disproportionately prescribed to patients 85 or older, who were likely to get the 110-mg twice-daily form considered less risky for bleeding than the 150 mg twice-daily form also available in Canada. The 110-mg twice daily dose studied in RE-LY was never approved in the US.

Dabigatran's safety record was good in the RELY-ABLE long-term study of patients from the RE-LY trial, including elderly patients, according to the new report's authors, led by Yan Xu (Queen's University, Kingston, ON). Still, "growth in the uptake of novel oral anticoagulants in very old patients, a group at high risk of bleeding, signals the need to evaluate outcomes in clinical practice to better guide the use of these agents."

The group looked at prescription trends across Ontario for the three oral anticoagulants; by September 2012, dabigatran made up 17.2% of oral-anticoagulant prescriptions. Rivaroxaban accounted for only 3.9% and so was left out of further analysis.

Over the two-year period:

  • Dabigatran use climbed from three per 100 000 population to 274 per 100 000 population (p<0.001).

  • Monthly warfarin prescription decreased from 1526 to 1316 per 100 000 population.

  • Dabigatran prescriptions were most common among patients aged >85; the second greatest use by age was in those 65 to 84 years.

From April to September 2012, 87.3% of dabigatran prescriptions were filled by patients aged >65 years, compared with 83.2% of RE-LY patients of the same age (p<0.001).

In the final month, more than half of dabigatran prescriptions for the elderly were for the 110 mg twice-daily form. The prevalence was 58.8% for patients aged 65 to 84 years and 93.6% for those older than 84.

An accompanying commentary from Dr Michiel Coppens (McMaster University, Hamilton, ON) and colleagues says the findings "are encouraging and the pattern of uptake of these agents is supported by the data from the randomized trials"[2].

But if clinicians want results for their patients like those in the trials, the group writes, they should prescribe the new oral anticoagulants "for the right patient and at the right dose, with appropriate follow-up and periodic monitoring of renal function," which they define as at least annually.

The study was funded by the Canadian Institutes of Health Research. Xu had no disclosures. Disclosures for the coauthors are listed in the paper. Coppens declares receiving research grant, travel support and lecture fees from Boehringer-Ingelheim and lecture fees from Bayer; disclosures for the other editorialists are listed in the paper.

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