Aims: In atrial fibrillation (AF) patients, age >or=75 years is one of the major risk factors for stroke. However, it is not clear if an upper limit for the indication to OAT exists.
Methods and results: For this reason, we performed a prospective study on 290 AF patients on OAT aged >or=75 years (median age 82 years, total follow-up period 814 pt/years) followed by our Anticoagulation Clinic. Seventeen major bleeding events were recorded (rate 2.1 x 100 pt/years), 11 of which cerebral (1.35 x 100 pt/years). The occurrence of major bleedings was associated with history of previous TIA or stroke [OR 3.4 (1.1-12.5), p=0.01] and with diabetes [OR 4.4 (1.3-14.7) p=0.01]. We found a trend to a progressive increase in the rate of bleeding risk with the increase of the CHADS2 score: patients with score 4-6 showed a rate of 3.4 x 100 pt/years with respect to 1.5 x 100 pt/years of patients with lower score. Number Needed to Harm (NNH) was calculated in relation to different classes of age (75-89, 80-84, >or=85 years) and to CHADS2 score. For patients in CHADS2 score 1-3 NNH remained stable across the different age classes. Instead for patients in CHADS2 score 4-6, NNH varied among the 3 groups of ages, reaching a value of 10 in patients >or=85 years.
Conclusion: Our data suggest that: 1) in AF patients older than 75 years with CHADS2 score 1-3 the risk of bleeding is low, 2) in AF patients >85 years with CHADS2 4-6 the risk of bleeding is high so that the use of OAT should be highly individualised.