[Which factors are associated to hemorrhagic adverse drug events related to antivitamin K?]

Abstract

Introduction: Hemorrhagic events constitute a major risk for patients on oral anticoagulant therapy.

Patients and methods: We conducted a prospective survey of all patients taking oral anticoagulants and admitted to the emergency room of Grenoble University Hospital over a period of 10 months. The objective was to identify the causes of drug-induced adverse hemorrhagic events, and whether they were related to health care practices or patient behavior concerning their treatment.

Results: Two hundred and sixteen patients treated with oral anticoagulants were identified and 68 of them had a hemorrhagic adverse drug event. Not taking into account prior medial history before prescribing an anticoagulant was noted for 21 of the patients who experienced a hemorrhagic event (p = 0.0003). In addition, compared with patients who had not had a hemorrhagic event, inadequate prescribing with regard to doses and administration frequency there were also more common in the hemorrhagic event group (p < 0.0001). Pharmacists delivering the drugs had not intervened to correct drug interactions, contraindications and inadequate doses in 72% of patients with hemorrhage (p < 0.0001). Other factors associated with increased the risk of hemorrhage were self-medication, not taking the prescribed drug at a predefined time of the day, insufficient INR monitoring and poor compliance (p < 0.0001).

Discussion and conclusion: To achieve the beneficial effects expected with anticoagulants, physicians must carefully comply with prescription recommendations, especially for elderly patients. Pharmacists delivering the drugs should also intervene more readily when required.