Patients who are using warfarin, an oral anticoagulant with narrow therapeutic index, needs to be followed up regularly. The index that has been used to monitor the result of using the medicine is International Normalized Ratio (INR). The gold standard of the method to measure INR is to measure using a specific device in the laboratory. However, the laboratory measurement requires resources and capacity, and therefore can be done in only some more advanced health care institutions. On the other hand, there is a new technology, namely Point of Care (POC) system, that allows the less advanced health care institutions to be able to measure INR as well. This should be beneficial for patients undergoing warfarin treatment since they would not have to travel a long distance to be followed up, but they can go to a nearer health care institution instead.