Assessment of healthcare professionals' knowledge about warfarin-vitamin Kdrug-nutrient interactions

Objective: Dietary vitamin K can interact with oral anticoagulant drugs and interfere with their therapeutic safety and efficacy. Therefore, knowledge about drug-nutrient interactions involving vitamin K possessed by physicia ns, pharmacists, dietitians and nurses practicing anticoagulant therapy was assessed. Methods: Healthcare practitioners were surveyed using a 30-question, 98-ite m questionnaire on the most common and/or important food interactions with warfarin, drug interactions with warfarin and general drug-nutrient interac tions involving vitamin K. The study sample included 160 randomly selected healthcare providers (40 physicians, pharmacists, dietitians and nurses) fr om 10 hospitals with 200 to 1000 beds from six Massachusetts regions. Rando m selection was conducted from a pool of selected healthcare providers prac ticing anticoagulant therapy who counsel patients receiving warfarin. Results: All surveys were completed within three months of the start of the study, and all participants provided usable data for statistical analysis. The mean scores (+/-SD) on the overall test were 72.5+/-9.0 for pharmacist s, 62.5+/-0.6 for physicians, 56.9+/-8.8 for dietitians and 50.2+/-9.3 for nurses, with 100 being a perfect score. Pharmacists scored significantly hi gher in the area of drug interactions (75.9+/-11.3, p<0.05). Dietitians sco red higher in the area of food interactions (73.0+/-10.3). No significant d ifferences between physicians and pharmacists were evident on general drug- nutrient interactions. While over 87% of the healthcare professionals corre ctly identified some common foods containing large amounts of vitamin K, su ch as broccoli and spinach, fewer than 25% were able to identify others suc h as pea soup, coleslaw and dill pickles. Conclusions: Although the healthcare professionals surveyed in this study a ppear to have demonstrated some proficiency in their respective areas of ex pertise. they exhibited less knowledge in others. Therefore, additional tra ining and integration of knowledge and expertise about drug-nutrient intera ctions among healthcare professionals are essential to provide appropriate patient counseling and optimal therapeutic outcomes.