Inappropriate anticoagulant dosing common in older patients with AF
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An analysis of the ongoing SAGE-AF trial revealed that approximately 23% of geriatric patients with atrial fibrillation and prescribed a direct oral anticoagulant received inappropriate dosing.
Most of these patients were underdiagnosed and approximately 11% were identified using drug-drug interaction criteria and would have otherwise been misclassified, according to research published in the Journal of the American Heart Association.
SAGE-AF is an ongoing trial examining the association between the variables of geriatric assessment including frailty, cognitive impairment, sensory impairments, social isolation and depression, and AF outcomes in patients aged at least 65 years.
Using an algorithm to analyze direct oral anticoagulant dose appropriateness that assessed drug-drug interactions, age, renal function and body weight, researchers found that 23% of participants received inappropriate dosing, of which 78% were underdosed and 22% were overdosed.
The cohort included patients (mean age, 74 years; 49% women; 82% white) with AF aged at least 65 years with CHA2DS2-VASc score of at least 2 and no anticoagulant contraindications.
Multivariable regression analyses determined that older patients, those with higher CHA2DS2-VASc score and/or a history of renal failure were associated with inappropriate dosing (P < .05). However, variables tied to geriatric-related impairment were not associated with inappropriate dosing of direct oral anticoagulants.
“Reasons for potentially inappropriate dosing may include prescriber perception of higher bleeding risk in older patients or those with renal failure,” Saket Sanghai, MBBS, of the Knight Cardiovascular Institute at Oregon Health and Science University, and colleagues wrote. “Interestingly, participants with higher CHA2DS2-VASc score, ie, higher thromboembolic risk, were more likely to be taking a potentially inappropriate direct oral anticoagulant dose, even after adjusting for renal failure and major bleeding. This may be driven by age. Since the majority of the potentially inappropriate prescribing we identified was underdosing, our results suggest that older patients and those at higher stroke risk may be at increased risk for receiving subtherapeutic doses of direct oral anticoagulants.”
Patients were excluded from the study if they had a contraindication to oral anticoagulation or an additional indication apart from AF, including mechanical heart valves or venous thromboembolism, the researchers reported.
“Overlooking drug-drug interactions was a common reason for inappropriate dosing,” Sanghai told Healio. “We believe that clinicians should systematically assess for drug-drug interactions, in addition to age, body weight and renal function, for prescription of accurate direct-acting oral anticoagulant dose. Perhaps involvement of a specialist pharmacist is warranted for all such prescriptions.
“Our next research endeavor is to determine the association between dosing and clinical outcomes (bleeding and stroke) as well as strategies to prevent unintentional inappropriate dosing by prescribers,” Sanghai said in an interview. – by Scott Buzby
Disclosures: One author reports he received grant support from Apple Computer, Biotronik, Bristol-Myers Squibb, Boehringer Ingelheim, Pfizer, Philips Healthcare and Samsung; received consultancy fees from Bristol-Myers Squibb, Boston Biomedical Associates, Flexcon, Pfizer and Rose Advisors; and inventor equity in Mobile Sense Technologies. The other authors report no relevant financial disclosures.
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