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Low-intensity warfarin did not reduce risk of venous thromboembolism or death after TJA
Published results showed the noninferiority criterion of risk of venous thromboembolism or death was not met when low-intensity warfarin was compared with standard-intensity warfarin in patients who underwent total joint arthroplasty.
“Based on these results, it is reasonable to use the lower target [international normalized ratio] INR for the majority of patients who are standard risk and reserve the higher target INR for the minority of patients who are at higher risk for [venous thromboembolism] VTE and who also are not at increased risk for bleeding,” Robert L. Barrack, MD, co-author of the study, told Healio.com/Orthopedics.
Barrack, Brian F. Gage, MD, MSc, and colleagues randomly assigned 1,650 patients aged 65 years or older who were undergoing total hip or knee arthroplasty to receive either low-intensity warfarin (INR of 1.8; n=823) or standard-intensity warfarin (INR of 2.5; n=827), as well as either genotype-guided or clinically guided warfarin dosing. Researchers considered the composite of VTE within 60 days or death within 30 days as the primary outcome.
Overall, 96.8% of patients received at least one dose of warfarin and were included in the primary analysis. Results showed 5.1% of patients in the low-intensity warfarin group experienced the primary composite outcome of VTE or death compared with 3.8% of patients in the standard-intensity warfarin group. Researchers found 0.4% and 0.9% of patients in the low-intensity and standard-intensity groups, respectively, experienced major bleeding, while 4.5% of patients in the low-intensity group and 12.2% of patients in the standard-intensity group had INR values of four or more.
“Although [Genetic Informatics Trial] GIFT found that targeting INR values around 1.8 had excellent safety in terms of bleeding, the trial did not prove that this level of anticoagulation was equally effective at preventing venous thromboembolism,” Gage told Healio.com/Orthopedics. “The rate of venous thromboembolism was 1.3% higher among the 804 patients randomized to a target INR of less than two, so I recommend against routinely using a low level of anticoagulation in this population.” – by Casey Tingle
Disclosures: Gage reports no relevant financial disclosures. Please see the study for a list of all other authors’ relevant financial disclosures.
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Gage BF, et al. JAMA. 2019;doi:10.1001/jama.2019.12085.