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

Abstract 

Aims

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 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.

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 CHADS₂4–6 the risk of bleeding is high so that the use of OAT should be highly individualised.

Keywords: Atrial fibrillation, Old patients, Bleeding risk, Oral anticoagulant therapy, CHADS₂ score