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

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.