Warfarin use and risk of knee and hip replacements

Ballal P, Peloquin C, Boer CG, Neogi T · Annals of the Rheumatic Diseases

The comparison that removes confounding by indication, because both groups needed anticoagulating: warfarin users had 1.59 times the risk of knee or hip replacement compared with DOAC users (95% CI 1.31-1.92), and longer warfarin use carried higher risk.

Population

Adults with atrial fibrillation newly prescribed warfarin or a direct oral anticoagulant in a UK primary-care records database; 857 joint-replacement cases and 3,428 matched controls

Intervention

Warfarin (a vitamin K antagonist)

Comparator

Direct oral anticoagulants, which do not touch vitamin K

Limitations

Nested case-control within a records database, so joint replacement stands in for end-stage osteoarthritis and radiographs were not read; channelling between warfarin and DOAC prescribing may still differ by frailty and renal function.