Vitamin K antagonists in patients with nonvalvular atrial fibrillation: appropriateness and quality of treatment in an Italian cohort

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Vitamin K antagonists (VKA) are highly recommended in patients with atrial fibrillation for their efficacy in preventing stroke. However, there is a lack of data on oral anticoagulation (OAC) with VKA overall treatment (i.e. from writing the prescription to time spent in therapeutic range) in patients discharged from hospital with a diagnosis of atrial fibrillation.


The aim of this study was to assess the adherence to stroke prevention guidelines in a cohort of patients discharged with atrial fibrillation from the two hospitals of the Agency for Health Services no. 3 ‘Upper Friuli’.


All patients discharged from the hospitals with a diagnosis of nonvalvular atrial fibrillation during the year 2009 were enrolled in this study. Record linkage for the previous 5 years and pharmaceutical data were used to assess comorbid conditions (ICD9-CM) and to calculate congestive heart failure, hypertension, age at least 75 years, diabetes and stroke (CHADS2) scores. Prescription orders were obtained from discharge letters. Patients’ adherence to VKA prescription was assessed through pharmacy records, and prothrombin/international normalized ratios (INR) for a period of 180 days after discharge from the whole ‘Upper Friuli’ laboratories. A patient was considered to have purchased VKA if at least one drug purchase was found in the pharmacy records. Time in therapeutic range (TTR) was calculated in patients who had at least two INR measurements.


In 2009, 509 patients (mean age 80 ± 8 years) were discharged with atrial fibrillation from ‘Upper Friuli’ hospitals (90% from internal medicine); of these, 284 patients (55.8%) had a CHADS2 score greater than 1 and no contraindications to VKA therapy at discharge. Within this subgroup, 112 patients (39.4%) received VKA prescription at discharge; of these, 84 (29.6%) purchased VKA and 58 patients had a TTR of at least 65% (20.4%).


VKA prescription for atrial fibrillation patients is low and not explained by present or past comorbid condition. A second failure is represented by patients’ low compliance. Overall, adherence to VKA guidelines in atrial fibrillation is scarce.

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