Dabigatran increasingly being used off-label

By Piriya Mahendra, medwireNews Reporter

Dabigatran has increasingly been used for off-label indications, including venous thromboembolism, in the USA between 2007 and 2011, a study suggests.

G Caleb Alexander (Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA) and colleagues found that use of dabigatran increased from 0.062 million quarterly visits to 0.363 million quarterly visits from the fourth quarter of 2010 to the last quarter of 2011. This finding reflects its growing share of oral anticoagulant visits during this period (3.1-18.9%), say Alexander and team.

"Our findings suggest that dabigatran has been rapidly adopted into ambulatory practice in the USA, primarily for treatment of atrial fibrillation [AF] but increasingly for off-label indications, and thus far without evidence of an effect on the widespread undertreatment of AF," they report.

Before the introduction of dabigatran in the last quarter of 2010, approximately 60.5% of AF patients were treated with warfarin. This decreased to 44.4% in the last quarter of 2011 after dabigatran's introduction. However, the percentage of AF patients in the last quarter of 2010 who were treated with dabigatran increased from 4.0% to 16.9% in the last quarter of 2011.

Overall, 92% of all dabigatran treatment visits in the last quarter of 2010 were for AF, decreasing to 63% of all treatment visits in the last quarter of 2011. The most common off-label uses of dabigatran in the last quarter of 2011 were coronary artery disease (7% vs 6% in the last quarter of 2010), hypertensive heart disease (9% vs 7% in 2010), and venous thromboembolism (18% vs 15% in 2010).

Expenditure related to dabigatran increased rapidly from US$ 16 million (€ 12 million) in the last quarter of 2010 to US$ 166 million (€ 129 million) in the last quarter of 2011, exceeding the total expenditure on warfarin in the last quarter of 2011, of US$ 144 million (€112 million).

The authors note that there was no evidence to suggest that the widespread undertreatment of AF changed after dabigatran was introduced.

"Despite its limited use, the aggregate direct cost of dabigatran now exceeds that of warfarin," they write in Circulation: Cardiovascular Quality and Outcomes.

"Significant shifts in oral anticoagulant use are likely as additional therapies become available and effectiveness accrues regarding their comparative safety and effectiveness relative to conventional therapies."

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