Study Objective. To evaluate the adequacy of anticoagulation in patients wi
th atrial fibrillation (AF) coming to a hospital.
Design. Retrospective medical record review
Setting. Tertiary care hospital.
Patients. Consecutive patients with a history of AF who had been prescribed
warfarin and who had the international normalized ratio (INR) measured whe
n they arrived at the hospital. Those who developed AF as a complication du
ring hospitalization were excluded.
Measurements and Main Results. Of 1085 patients, 375 (mean age 73 yrs, 56.3
% men) were eligible for further evaluation. Most had nonvalvular AF; in 44
.5% the INR was subtherapeutic, in 36.5% it was therapeutic, and in 18.9% i
t was supratherapeutic. Patients admitted for any thromboembolic event and
for ischemic stroke were significantly more likely to have subtherapeutic I
NRs.
Conclusion. It is well documented in the literature that warfarin is underp
rescribed, but our results suggest that even in treated patients, about hal
f are inadequately protected from thromboembolism.