Patients’ interpretation of responsibility with warfarin therapy

Rebekka Schrecengost, Pharm.D., Essentia Health

Background: Even for patients who take their medications as directed, Internal Normalized Ratio (INR) values for those receiving warfarin can vary for numerous reasons. Most patients are not aware of the misconceptions involved in the cause of INR variation, and this may lead to misplaced blame for an INR outside the target range.

Purpose: The study by Gillespie et al. sought to characterize the experience of warfarin treated patients regarding medication administration, communicating with clinical pharmacists, and INR monitoring.

Study Design: The study included 40 telephone interviews among eight Veterans Health Administration outpatient anticoagulation clinics in the New England region. Of the 40 patients included, there were 34 males and six females. The mean age of the participants was 73.4 years old. The duration of warfarin therapy varied among patients, but each person had experienced an INR value that was out-of-range at some point in the past.

Results: Interview results indicated that many patients view variation in INR values as their fault due to dietary and lifestyle behaviors. Patients often felt as though the pharmacist was blaming them for their INR variation, based on the questions that were asked to identify the cause of INR variation. This perception may indirectly lead to adverse consequences such as withholding information from anticoagulation care providers or skipping appointments. Quantitative data regarding the study results was not included in the article.

Conclusions: Qualitative interviews with patients receiving warfarin resulted in misinterpretation of questioning about INR variation, indicating that patients are responsible for failing to meet INR goals. When patients feel they are to blame for INR variation, they are sometimes reluctant to be honest with a pharmacist about their behaviors, potentially leading to suboptimal clinical outcomes.

Key Point: An INR value outside the goal range poses a teachable moment for patient education. Although it is necessary to ask the right questions to evaluate INR variation, pharmacists may consider emphasizing that not all out-of-range INR values are due to specific action by the patient and sometimes variation occurs due to factors that are beyond one’s control.


  1. Gillespie C, Rose AJ, Petrakis BA, Jones EA, Park A, McCullough MB. Qualitative study of patient experiences of responsibility in warfarin therapy. Am J Health-Syst Pharm. 2018;75(22):1798-1804.