Improving patient drug adherence requires attention
MUNICH – Treatment of real-world patients newly diagnosed with atrial fibrillation using a direct oral anticoagulant led to benefits that tracked the advantages previously seen in randomized, controlled trials of these drugs, based on findings from more than 26,000 patients enrolled in a global registry.
Mitchel L. Zoler/MDedge News
Dr. A. John Camm
Atrial fibrillation patients enrolled in the GARFIELD-AF(Global Anticoagulant Registry in the Field) study who started treatment with a direct oral anticoagulant (DOAC) had a 19% relative risk reduction in all-cause mortality during 2 years of follow-up, compared with patients on an oral vitamin K antagonist (VKA) regimen (such as warfarin), a statistically significant difference after adjustment for 30 demographic, clinical, and registry variables, A. John Camm, MD, said at the annual congress of the European Society of Cardiology. The analysis also showed trends toward lower rates of stroke or systemic thrombosis as well as major bleeding events when patients received a DOAC, compared with those on VKA, but these differences were not statistically significant, reported Dr. Camm, a professor of clinical cardiology at St. George’s University of London.
The analyses run by Dr. Camm and his associates also confirmed the superiority of oral anticoagulation. There was an adjusted 17% relative risk reduction in all-cause mortality during 2-year follow-up in patients on any form of oral anticoagulation, compared with patients who did not receive anticoagulation, a statistically significant difference. The comparison of patients on any oral anticoagulant with those not on treatment also showed a significant lowering of stroke or systemic embolism, as well as a 36% relative increase in the risk for a major bleeding episode that was close to statistical significance.
These findings in a registry of patients undergoing routine care “suggest that the effectiveness of oral anticoagulants in randomized clinical trials can be translated to the broad cross section of patients treated in everyday practice,” Dr. Camm said. However, he highlighted two important qualifications to the findings.
First, the analysis focused on the type of anticoagulation patients received at the time they entered the GARFIELD-AF registry and did not account for possible changes in treatment after that. Second, the analysis did not adjust for additional potential confounding variables, which Dr. Camm was certain existed and affected the findings.
“I’m concerned that a confounder we have not been able to account for is the quality of medical care that patients received,” he noted. “The substantial reduction in mortality [using a DOAC, compared with a VKA] is not simply due to reductions in stroke or major bleeding. We must look at other explanations, such as differences in quality of care and access to care.”
The analyses have also not yet looked at outcomes based on the specific DOAC a patient received – apixaban, dabigatran, edoxaban, or rivaroxaban – something that Dr. Camm said is in the works.
GARFIELD-AF enrolled nearly 35,000 patients with newly diagnosed atrial fibrillation and at least one stroke risk factor in 35 countries from April 2013 to September 2016. The analysis winnowed this down to 26,742 patients who also had a CHA2DS2-VASc score of at least 2 (which identifies patients with a high thrombotic risk) and had complete enrollment and follow-up data.
GARFIELD-AF was funded in part by Bayer. Dr. Camm reported being an adviser to Bayer, Boehringer Ingelheim, Daiichi Sankyo, and Pfizer/Bristol-Myers Squibb.