Risk of bleeding in very old atrial fibrillation patients on warfarin:: Relationship with ageing and CHADS2 score

Alms: In atrial. fibrillation (AF) patients, age >= 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 OATaged >= 75 years (median age 82 years, total follow-up period 814 pt/years) followed by our Anticoagutation 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 CHADS(2), score: patients with score 4-6 showed a rate of 3.4x100 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, >= 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 >= 85 years. Conclusion: Our data suggest that: 1) in AF patients older than 75 years with CHADS(2) score 1-3 the risk of bleeding is low, 2) in AF patients >85 years with CHADS(2)4-6 the risk of bleeding is high so that the use of OAT should be highly individualised. (c) 2007 Elsevier Ltd. All rights reserved.