Evaluation of warfarin prescription labels

Excerpt

Introduction Due to warfarin’s frequent dosage adjustments and the potential for serious adverse consequences (bleeding, bruising, etc.), the dosage must be individualized for each patient according to the indication for therapy and patient response to the medication as measured by prothrombin time (PT)/international normalized ratio (INR). Ideally when there are dosing changes, the dosing instructions written on the prescription label should be the same as the patient’s actual dosage regimen. Patients may take incorrect warfarin doses secondary to having incorrect directions on the prescription label, which may lead to adverse events. Dosage instructions may not be reissued for each difference in dosage to save time, avoid waste of multiple bottles of medication, and to reduce cost. Objective To ascertain whether a discrepancy exists between the warfarin dosage listed on the prescription bottle label dispensed from the pharmacy and the patients’ actual dosage instruction obtained from the anticoagulation clinic at the Loma Linda VA Medical Center, and if the discrepancy existed, to determine its magnitude. If discrepancies existed, examine if there was a >10% difference in the weekly dose. Method A retrospective chart review utilizing an MS DOS based program Clinstat for randomization scheme of 300 charts was carried out of patients 18 years or older with active management of anticoagulation and received warfarin prescription from Loma Linda VA Medical Center between May 1,2005 and December 1, 2005. Results Of the 298 charts, which met inclusion criteria, 12 (4%) were unable to be assessed due to lack of patient’s inability to recall warfarin dosage documented in chart. Of the remaining 286, the mean age was 69.8 and males constituted 98.9%. Discrepancy was noted in 161 charts (56%). Of those, 122 (76%) had a >10% discrepancy: with a mean of 32%, and range of 11–100%. Conclusion/Discussion The results of the warfarin label retrospective review demonstrated that there was a discrepancy between patient’s prescription bottle label and patient’s verbalized dosage in over half of the patients’ from the anticoagulation clinic with a mean discrepancy of 32% of the warfarin dose and 76% of the discrepancies exceeding 10% of the warfarin dose. This study raises a question whether warfarin labels should simply read, “take as directed,” or with the specific dosing instructions provided on a separate instruction sheet or calendar. This study may also be significant to fuel future studies to look into the greater impact of this discrepancy such as patient safety (bleeding rates, hospitalization rates), and cost (new labels, medication waste). …