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

AimsIn 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 resultsFor this reason, we performed a prospective study on 290 AF patients on OAT aged ≥ 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 × 100 pt/years), 11 of which cerebral (1.35 × 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 × 100 pt/years with respect to 1.5 × 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.ConclusionOur 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 CHADS24–6 the risk of bleeding is high so that the use of OAT should be highly individualised.