Given the morbidity and mortality potential of disease states for which physicians administer warfarin, achievement of therapeutic INR (t-INR) values as recommended by the American College of Chest Physicians (ACCP) is crucial. This study was designed to calculate the percentage of t-INR values, compare management of warfarin anticoagulation between primary care physicians (defined as family practitioners and internists), cardiologists, and pulmonologists, and examine if frequency of INR monitoring affects percentage of t-INR values.
A retrospective chart review was conducted on patients receiving warfarin. Data abstracted included patients’ demographics, indication for anticoagulation, physician specialty managing the patient, the INR values and dates of each measurement. The comparison between t-INR measurements was done using the Chi-squared test. The student t-test was used in comparing the frequency of measurement.
The charts of 244 patients (104 PCP patients, 117 cardiology patients, and 23 pulmonology patients) were reviewed and a total of 6952 INR values were recorded. Patients were categorized into 4 groups based on indication for anticoagulation, and the tableIndicationPCP %Cardio- logists %Pulmono- logists %p value PCP vs Cardiologistsp value PCP vs Pulmono- logistsDeep venous thrombosis/ pulmonary embolus (DVT/PE)51.456.948.3.444.313Atrial fibrillation (AF)46.256.7n/a<.0000001n/aMechanical heart valve (MHV)35.042.7n/a.007n/aAF + MHV34.245.3n/a.031n/aOverall45.652.348.3.0000001n/abelow represents the percentage of t-INR values.When comparing INR values below the critical value of 1.5, 12.2% of INR values managed by PCP, 7.0% by cardiologists and 10.5% by pulmonologists were below 1.5. Cardiologists were statistically more likely than PCP to keep the INR value above 1.5 (p=.000001) and no statistical significance existed between pulmonologists and PCP (p=.093). PCP, cardiologists, and pulmonologists measured INR values on average every 32.51 days, 19.41 days and 29.88 days respectively (PCP vs cardiologists, p<0.05).CONCLUSIONS: When comparing PCP and cardiologists, statistical significance was achieved for all indications except DVT/PE, demonstrating that cardiologists are more likely to keep the INR value within range and above 1.5. No statistical significance was found between PCP and pulmonologists.
A t-INR level is more likely to be attained, especially for AF and MHV, when cardiologists manage warfarin. This could be explained by a statistically higher frequency of INR measurements by cardiologists.
S.J. Khandhar, None.