Surgeons have historically adjusted the dosage of warfarin in our institution. To more efficiently utilize the skills of both surgeons and pharmacists, the dosage of warfarin was delegated to pharmacists.
To compare the effectiveness of pharmacists to physicians in obtaining therapeutic anticoagulation upon initiation of warfarin therapy. Secondary objectives included: the percentage of days when the INR was >4 or <2, the time to stabilize the INR within the therapeutic range, and the percentage of patients experiencing at least one major bleed.
Cardiac Surgery wards of a tertiary teaching hospital.
This study was a retrospective chart review of patients who received warfarin following cardiac valve surgery. Pharmacists utilized a warfarin nomogram to manage patients; physicians dosed independently.
Main Outcome Measures
Percentage of therapy days within the target INR range; percentage of therapy days with INR less than 2 or greater than 4.
This study consisted of 227 patients (pharmacist group: 97; physician group: 130). There was no difference found between the two groups in the percentage of days in the therapeutic range (p-value=0.27), the percentage of days with INR <2 (p-value=0.06), the percentage of patients discharged before their INR stabilized (p-value=0.91) and the percentage of patients with a major bleed (p-value=0.72). The pharmacist group had 6% fewer days of INR >4 than the physician group and this was statistically significant (p-value of <0.001).
Pharmacists are equally safe and effective as physicians when managing warfarin therapy in patients who have undergone cardiac valve replacement.