[Hemorrhagic complications of oral anticoagulant therapy: results of a prospective multicenter study ISCOAT (Italian Study on Complications of Oral Anticoagulant Therapy)].

BACKGROUND: To assess the incidence of bleeding complications during oral anticoagulant therapy (OAT) in a population of patients representative of daily practice in Italian anticoagulation clinics. DESIGN: prospective, inception-cohort, multicentre. SETTING: Thirty-four anticoagulation clinics federated in the Italian Federation of Anticoagulation Clinics. PATIENTS: 2745 consecutive patients, included from beginning of their first OAT course. Most patients were aged between 60 and 79 y (57.8%), with 8% being > or = 80 y. Venous thromboembolism was the most frequent indication for OAT (one third of all the patients), followed by non ischemic heart disease which mainly included atrial fibrillation (16.8% of patients). Warfarin (in 63.8% of patients) and acenocoumarol were the only anticoagulant drugs used. The targeted anticoagulation intensity was low (INR 2.8) in the remainder. OUTCOMES: Fatal, major and minor bleeding events. Thrombotic events were also recorded, though not analyzed in the present report. FINDINGS: During the 2011 patient-years (pt-y) of follow-up, 153 bleeding complications (7.6% pt-y) were recorded--5 fatal (all cerebral haemorrhages, 0.25% pt-y), 23 major (1.1% pt-y) and 125 minor (6.2% pt-y). The rate of events did not vary according to sex, coumarin type, size of enrolling centre or targeted therapeutic range; it was higher in older patients (10.5% pt-y in those aged > or = 70 y, relative risk--RR--1.75, p or = 7 INR categories respectively (RR for INR levels > 4.5 = 7.91, p 70 y; arterial vascular disease as indication for OAT; first 3 months of treatment; INR values > or = 4.5. OAT has become safer in recent years, particularly if monitored in special anticoagulation clinics. Caution should be exercised when prescribing OAT in elderly patients and the intensity anticoagulation levels should be closely monitored to minimize incidental periods of overanticoagulation.