TORONTO—Nephrologists should determine the estimated glomerular filtration rate (eGFR) at least twice a year for patients who have severely impaired renal function and who are prescribed one of the novel oral anticoagulants (NOACs) for a comorbid condition, a cardiologist advised.

Speaking at the Canadian Cardiovascular Congress, Jean Grégoire, MD, told listeners that NOACs are potentially dangerous in patients with renal failure because the medications are predominantly renally excreted and thus could accumulate and cause catastrophic bleeding.

Dr. Grégoire stressed the importance of this during a presentation of the results of a survey of 62 clinicians suggesting that some patients with an eGFR of below 30 mL/min/1.73 m2 are being prescribed NOACs.

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“We have to emphasize the need to follow patients on NOACs more than patients on other medications, in order to avoid deleterious consequences,” said Dr. Grégoire, who was the principal investigator of survey and practices at the Montreal Cardiology Institute. “We have to be sure that the kidney function is stable and that other medications are not introduced that can reduce the renal function further.”

The FDA announced in December 2011 that its officials are evaluating reports of serious bleeding events in patients taking the NOAC dabigatran, some of whom had compromised renal function. The agency, however, has not yet followed the lead of Health Canada, which in March 2012 changed its recommendations to stipulate that renal function should be assessed in all patients prior to being given dabigatran, and that the medication should not be given to those with a creatinine clearance below 30 mL/min.

Dr. Grégoire and his colleagues conducted the survey (the Physician Practice Assessment—Stroke Prevention & Atrial Fibrillation Evaluation) because they suspected many physicians are not aware of, or are not compliant with, these new recommendations. Furthermore, many physicians rely on serum creatinine rather than eGFR to assess kidney function, despite eGFR being a better overall index of renal function, Dr. Grégoire noted.

The researchers administered the survey to 42 family physicians and 20 specialists including cardiologists, internists, and neurologists between May and August 2011. The survey questionnaire asked about their perceptions about their current management of atrial fibrillation and stroke risk. Each physician also answered questions after completing visits with approximately 15 atrial fibrillation patients. In total, the investigators gathered data from 663 patient visits.

The patients’ mean age was 74 years and 52.9% were male. In all, 75.6% had hypertension, 54.4% had dyslipidemia, 37.3% had coronary artery disease, and 31.7% had diabetes. In addition, 53% had an eGFR of above 60; 41% of patients over age 80 years had an eGFR of 30-60.

Older patients were less likely to be taking anticoagulant medication, with 18% of those aged 65 years or under taking no anticoagulants compared with 24% of patients aged 66-80 years and 44% of those 80 years of age or older.

Some patients with compromised renal function were taking anticoagulants. Fifty of those with an eGFR of 60 or lower were taking dabigatran and approximately twice as many were taking warfarin.