Warfarin linked to greater hip, knee replacement risk
Click Here to Manage Email Alerts
Treatment with warfarin is associated with a significantly greater risk for hip or knee replacement compared with direct oral anticoagulants, according to a speaker at ACR Convergence.
“Over the last decade, we have research from our group at BU that has demonstrated the importance of vitamin K in the adequate functioning of the bone and cartilage,” Priyanka Ballal, MD, a rheumatology fellow at Boston University Medical Center, said at a virtual press conference at the meeting. “Vitamin K deficiency has been associated with osteoarthritis, both incidence and progression, and recent research shows that vitamin K supplementation may reduce osteoarthritis progression.”
“Warfarin is a commonly used anticoagulant for conditions such as atrial fibrillation, which is a common abnormal heart rhythm, and warfarin is used to prevent blood clots,” she added. “It does so by inhibiting activation of vitamin K-dependent proteins in the blood, but there are also vitamin K-dependent proteins in the bone and cartilage that are also affected by warfarin. What we don’t know is whether warfarin use can also cause progression of osteoarthritis, as demonstrated by vitamin K deficiency.”
To analyze the link between warfarin and the risk for knee or hip replacement, as a reflection of end-stage OA, Ballal and colleagues conducted a nested case-control study of data from the Health Improvement Network. According to the researchers, this database contains general practitioner-based electronic medical records from the United Kingdom representative of the general population. To minimize confounding by indication, the researchers limited their sample to adults aged 40-89 years with atrial fibrillation. They then compared warfarin with direct oral anticoagulants, focusing on patients enrolled for at least 1 year with their general practitioner between 2009 and 2018.
Patients with knee or hip replacement prior to 2014, or with severe comorbidities that would limit surgery, were excluded from the study. The researchers also excluded those who had used warfarin or direct oral anticoagulants during within 1 year prior to the study period, as well as those who used both during the study period. In all, the researchers identified 913 patients with knee or hip replacement between 2014 and 2018, with their surgery date set as the index date for their case. Each case was marched with up to four control individuals based on age and gender. The study included a total of 3,652 control individuals.
The researchers defined warfarin or direct oral anticoagulant use as receiving at least one prescription after study entry and within 1 year prior to the index date. Analyses were completed using conditional logistic regression, adjusting for potential confounders. Among the 913 included patients, 64.9% were classified as warfarin users, while 35.1% used direct oral anticoagulants. In the control group, 56.3% used warfarin and 43.6% had direct oral anticoagulants.
According to the researchers, after adjusting for potential confounders, patients who received warfarin demonstrated 1.57 times higher odds of knee or hip replacement than those treated with direct oral anticoagulants (aOR = 1.57; 95% CI, 1.30-1.89). When matched by practice ID to account for practice variation, the associated was diminished slightly, but still significant (aOR = 1.25; 95% CI, 1.03-1.52). In addition, the risk for knee or hip replacement increased with duration of warfarin, compared with direct oral anticoagulant exposure.
“Warfarin use was associated with a higher risk for hip and knee replacement compared to [direct oral anticoagulant] use,” Ballal said. “This risk appeared to increase with duration of use. This latter observation is extremely relevant, since people with atrial fibrillation often require lifelong anticoagulation. So, our study supports the importance of vitamin K in limiting the progression of osteoarthritis in patients with atrial fibrillation and raises the concentration of using DOACs over warfarin when indicated in patients with osteoarthritis.”
Collapse
Ballal P. Abstract 0934. Presented at: ACR Convergence 2020; November 5-9, 2020 (virtual meeting).
Read more about
Click Here to Manage Email Alerts