Long-term oral anticoagulant therapy in elderly patients.

Forty-nine patients aged 65-89 years, treated for 6 months-6 years (mean 3.9 years) over a total of 195 patient years, were studied. The efficacy of anticoagulant control or the occurrence of complications or treatment failures did not vary with the age, sex, social status, mobility, visual acuity, domiciliary supervision of medication or the indication for anticoagulation. A significant correlation was observed between the concomitant drug therapy and anticoagulant control (P less than 0.001) but not with the occurrence of complications and treatment failures. Poor anticoagulant control was observed particularly in those receiving drugs known to potentiate warfarin effect and in whom more changes were made to their concomitant drug therapy. Five patients who experienced six non-fatal haemorrhages (two major and four minor) showed poor overall anticoagulant control from the outset (P less than 0.01). The treatment failure rate was 4%.