MTAC patients were found to have better INR control compared to non-MTAC patients. A joint cooperation between physicians, pharmacists, and nurses should exist to achieve desired therapeutic outcomes.

We are delighted to read a good quality commentary on our article published in Journal of Pharmacy Practice. A realistic aspect related to bleeding has been raised in this letter. We have no major comments except for the conclusion that data from the published study should be ''reevaluated'' regarding relationship between knowledge about mechanism of action of warfarin and bleeding history of patients. An assessment of bleeding risk or event was not included in our study due to some important reasons which we have discussed below.Risk factors for bleeding include serious comorbid conditions or medical history, older age, concurrent medicines, and intensity of anticoagulation. Effectiveness and safety are influenced chiefly by vitamin K containing foods, by drugs or other substances which potentiate or inhibit warfarin metabolism, and by drugs which inhibit modulate function. These factors necessitate a careful drug history and knowledge of concurrent drug therapy; careful, often repeated, counseling; lifestyle modification and regular dose adjustment based on measured international normalized ratio (INR), and monitoring for bleeding tendency. More frequent monitoring may be needed during intercurrent illness. 1,2 Since we have not covered these aspects, the discussion about the risk of bleeding or bleeding as a complication was beyond the scope of the published article.As you have mentioned based on your findings that ''the duration between the onset of warfarin and the time of bleeding is shorter and the bleeding frequency within the first month of treatment is higher,'' but in our published study, we have excluded patients who have just started taking warfarin for less than a month. In our study, we relate knowledge about warfarin with ethnicity, education, medication therapy adherence clinic (MTAC) and non-MTAC, and so on and not with bleeding. Your suggestion could only be implemented if all authors agree to modify their objectives and exclusion and inclusion criteria stated in the published article, which is obviously not possible.Our study is still going on looking at the risk of bleeding and that part is not published yet. In our ongoing study on warfarin users, we have found significant differences between age groups in terms of worry about bleeding. Older subjects and females reported more limitation on daily life from concerns about bleeding risk. However, participants did not report any actual major bleeding or bruising which affected daily life. In our study, mean percentage days in range for all INR target range subgroups did not exceed more than 65%, implying appreciable periods when subjects would have been at some degree of risk for bleeding or thromboembolic events. 3 However, this assumption was not investigated and confirmed through any subjective or objective assessment in our study.Despite having been in clinical use for 60 years, warfarin therapy remains challenging because its effectiveness and safety depend upon maintenance of the patient's INR within a narrow therapeutic range to ensure e...