Volume 198 - Issue 6
An audit of dabigatran etexilate prescribing in Victoria
Authors: Sueh-li A Lim and Ellen Maxwell
Med J Aust 2013; 198 (6): 314-315. || doi: 10.5694/mja12.10942
Published online: 1 April 2013
Published online: 1 April 2013
To the Editor: In 2009, the RE-LY (Randomized Evaluation of Long-Term Anticoagulant Therapy) trial compared dabigatran etexilate with warfarin for prevention of stroke and systemic embolism in 18 113 patients with
non-valvular atrial fibrillation (AF)
and at least one additional risk factor
for stroke.1 In April 2011, it became accessible in Australia (Pradaxa; Boehringer Ingelheim) under a product familiarisation program funded by
the manufacturer; however, the Pharmaceutical ...
To the Editor: In 2009, the RE-LY (Randomized Evaluation of Long-Term Anticoagulant Therapy) trial compared dabigatran etexilate with warfarin for prevention of stroke and systemic embolism in 18 113 patients with non-valvular atrial fibrillation (AF) and at least one additional risk factor for stroke.1 In April 2011, it became accessible in Australia (Pradaxa; Boehringer Ingelheim) under a product familiarisation program funded by the manufacturer; however, the Pharmaceutical Benefits Advisory Committee expressed concern that without informed and appropriate prescription, clinical trial outcomes may not be reproducible.2 Case reports from Europe3 and New Zealand4 identified the need for caution when treating older patients, those with low body weight or patients with renal impairment because of the risk of serious bleeding.
We performed a retrospective audit of the available criteria of indication, renal function and time in therapeutic range (TTR) of 362 patients at a private anticoagulant clinic who were transferred from warfarin to dabigatran between 1 June 2011 to 30 November 2011. Patients recorded as having AF were presumed to have non-valvular heart disease, although this was not confirmed. The dose of dabigatran, the CHADS2 score (congestive heart failure, hypertension, age ≥ 75 years, diabetes, 1 point each; prior stroke or transient ischaemic attack, 2 points), the weight of the patient, and the patient versus clinician preference for therapy were not known to pathology service staff.
The patients in our cohort were older (mean, 76 years) than participants in the RE-LY trial (mean, 71 years). Fewer of our patients had significant renal impairment (14% had an estimated glomerular filtration rate [eGFR] < 50 mL/min/1.73 m2, versus 19% of RE-LY participants), but 2% had an eGFR < 30 mL/min/1.73 m2, and 12% had not had a renal function assessment in the past 12 months. Twenty-nine patients (8%) did not meet the indication of having non-valvular AF.
A RE-LY subanalysis suggested that dabigatran had no advantage over warfarin in reducing non-haemorrhagic stroke or death in patients with excellent international normalised ratio (INR) control (defined as TTR > 72.6%).5 In our cohort, TTR was assessed over a minimum of 6 months before patients were switched from warfarin to dabigatran, and the mean TTR (70%) was higher than in RE-LY (64%). In addition, one-third of our patients had TTR ≥ 79%, indicating high-quality anticoagulant control.
Our study confirms the prescription of dabigatran to a local population that differed from RE-LY participants in age, renal function and TTR, and occasionally for an unapproved indication. Although we cannot comment on clinical consequences, care should be taken in extrapolating positive outcomes to non-equivalent patient groups, and continuing education campaigns are needed.
Competing interests
No relevant disclosures.
Acknowledgements
We would like to thank Duncan Carradice for proofreading the original paper and providing constructive advice, and Shaun Fleming for his help with data collection.
References
- Connolly SJ, Ezekowitz MD, Yusuf S, et al. Dabigatran versus warfarin in patients with atrial fibrillation. N Engl J Med 2009; 361: 1139-1151. 0_BABDJBJC
- Department of Health and Ageing. Important new medicines listed on the PBS. http://www.health. gov.au/internet/ministers/publishing.nsf/Content/mr-yr11-nr-nr196.htm (accessed Sep 2011).
- Legrand M, Mateo J, Aribaud A, et al. The use of dabigatran in elderly patients. Arch Intern Med 2011; 171: 1285-1286. 0_i1142872
- Harper P, Young L, Merriman E. Bleeding risk with dabigatran in the frail elderly. N Engl J Med 2012; 366: 864-866. 0_i1142874
- Wallentin L, Yusuf S, Ezekowitz MD, et al. Efficacy and safety of dabigatran compared with warfarin at different levels of international normalised ratio control for stroke prevention in atrial fibrillation: an analysis of the RE-LY trial. Lancet 2010; 376: 975-983. 0_i1142878