Background Oral Anticoagulant Treatment (OAT) is the most common pharmacological treatment for prevention of stroke and thromboembolism in patients with atrial fibrillation or prosthetic heart valves. The major complication of OAT is the risk of bleeding. High intensity of anticoagulants and targeted International Normalised Ratio (INR) >3 are associated with a higher risk of haemorrhagic events. This risk is also related to the length of treatment, the concomitant use of drugs that interfere with haemostasis and with patient characteristics.

Purpose To evaluate the frequency, seriousness and outcome of haemorrhagic events in patients on OAT among all the Adverse Drug Events (ADEs) that lead people to the Emergency Room (ER).

Materials and methods The Hospital Pharmacist monitored patients who entered ER of ‘S. Giuseppe Moscati’ Hospital in Avellino because of ADEs over a period of four months. The cases of bleeding due to OAT were selected and analysed.

Results During the time considered 89 ADEs were detected in ER. 21 cases (about 24%) involved patients with OAT who used warfarin (71%) and acenocoumarol (29%) because of atrial fibrillation (91%) and prosthetic heart valves (9%). 52% of these ADEs were ‘not serious’ while the ‘serious’ ones were clinically important (10%), needed hospitalisation/a longer time in hospital (24%) or ended with the patient’s death (14%). Complete resolution after hospital treatments was achieved in only 19% of cases. The main ADEs detected were hematomas, epistaxis, gastrointestinal bleeds and two fatal intracranial bleeds in elderly women with increased values of INR. Patients involved were predominantly female (67%) and over 65 years of age (71%). About 5% of them used acetylsalicylic acid too.

Conclusions Pharmacovigilance activity produces new data and information that improves drug treatments. With the wide knowledge that comes from new investigations treatment is made safer.

No conflict of interest.