Long-term oral anticoagulation therapy and the risk of hip fracture in patients with previous hemispheric infarction and nonrheumatic atrial fibrillation.

Warfarin therapy has been demonstrated to reduce the risk of stroke in nonrheumatic atrial fibrillation (NRAF). We showed that long-term warfarin therapy reduces vitamin K and second metacarpal bone mineral density (BMD) in NRAF patients who had previous hemispheric infarction. To determine whether warfarin is associated with increased hip fracture risk, we compared the incidence of hip fracture between post-stroke patients receiving warfarin therapy and post-stroke patients without such therapy. Eighty-four post-stroke patients with NRAF who had been treated with warfarin and 93 post-stroke patients without warfarin were followed for 5 years and their incidence of hip fracture was compared. At baseline and 3 and 5 years later, sera were collected from both groups. Sera were assayed for undercarboxylated osteocalcin (ucOC), bone Gla protein and 25-hydroxyvitamin D (25-OHD). BMD was determined in second metacarpals. During 5 years, 8 hip fractures in the treated group and 9 hip fracture in the untreated group occurred (p = 0.92). After 5 years, serum ucOC concentrations were higher in treated patients (9.1 +/- 1.5 ng/ml) than in untreated patients (6.0 +/- 1.2 ng/ml). ucOC was significantly related to BMD in treated but not in untreated patients. Concentrations of 25-OHD were lower in both patient groups. Percent change of BMD from baseline was lower in treated patients than in untreated patients (p < 0.01). Long-term treatment with warfarin in stroke patients seems not to be associated with an increased risk of hip fracture.