Warfarin is effective in reducing the stroke risk in atrial fibrillation in the very elderly. This survey aimed to define characteristics and problems of patients aged≥80 with atrial fibrillation attending an outpatient anticoagulant monitoring service (AMS) in a university hospital.

All patients aged ≥80 from October 2007 to March 2008 were included.

One hundred and sixty-eight patients, average age 85.8±3.1 years, were included in the study. Average age of commencement was 81.3±4.5 years. Average length of time on warfarin was 4.8±3.3 years. Fifty-three percent of patients managed their own warfarin and took instructions for dosing. In their entire period on warfarin, 61% of patients had problems including bleeding, bruising, falls, medication interactions and erratic International Normalized Ratio (INR) readings. Seven percent of patients had INR readings of >8.0, necessitating emergency department assessment for reversal with vitamin K. The AMS staff had difficulty contacting 13% of patients with elevated INRs and missed appointments in 11%. In the 6 months, only 45% remained within target INR range of 2.5±0.75 in 90–100% of 10 consecutive readings. Sixteen percent were within target INR in ≤60% of readings. Seven percent of patients died, one from a subdural haemorrhage postfall. Fifteen percent were admitted to hospital.

The findings illustrate significant difficulties encountered by this elderly, vulnerable age group in proven effective treatment in atrial fibrillation. Changes need to be made to increase resources for monitoring in the community, including home visits, portable INR monitors and point-of-contact dose adjustment. Patients should be assessed carefully for risk to benefit ratio.