Reply to the Letter to the Editor Reply to Sidhu and MacGowan

We appreciate Dr Sidhu’s and Dr MacGowan’s interest in our study and their comments regarding this. At the time of submitting the manuscript, we were not aware of the study conducted by Sidhu and O’Kane [1]. It is an interesting study, which we should have referred to in our paper. The results found in this well-conducted randomized trial are in line with our results. The age of the patients does not seem to have an independent major impact on the ability to conduct selfmanagement and the results hereby obtained. Feasibility and good results has been demonstrated both in children (age from 2.2 to 15.6 years) [2] and in older patients (age from 65 to 80 years) [3]. However, self-management can only be offered to selected patients, who are able (both physically and mentally) to manage their own anticoagulation therapy, and this seems relatively independent of age. In our study, we had a narrow therapeutic range (target INR ^0.5); the same as in the study by Sidhu et al. We agree that the result of time within therapeutic INR target range is highly dependent of the therapeutic INR target range. All things being equal, a therapeutic INR target range of 2.0–4.0 will provide a higher time within therapeutic INR target range compared to a therapeutic INR target range of 2.0–3.0. The time within therapeutic INR target range also differs using different methods of calculation. This makes comparison between various studies difficult. Other methods to estimate the quality of treatment exist: the extent of deviation of INR-values from the INR target value, which shows correlation with the number of bleedings and tromboembolism [4]. The incidence of clinical endpoints (major tromboembolism and bleeding events) is the best method of quality assessment, but it requires many patients in order to get a statistically valid result, since the incidence of these complications is relatively rare. Conductions of such studies obviously require significant resources. As described in our paper, we recommend a thorough and structured training. Therefore, we agree with Dr Sidhu et al. in the importance of this, although others have presented good results merely by instructing patients in the function of the coagulometer [5]. Regarding the safety issue: we agree with Dr Sergeant that it is highly important the patient is not ‘left on his own’. The patient should have access to professional support regarding the treatment, and this requires certain demands to the health care system. We agree with Dr Sidhu et al. that the number of potential variables seems fewer in self-management compared to standard management. However, formalized guidelines are needed in to order to minimize the variables in self-management, e.g. the assessment of patient suitability, responsibility of the treatment, medical evaluation, training, exam and internal/external quality control of the coagulometer. These guidelines could be prepared in an international frame, using knowledge and experience from all centers.