Background: Commonly the frequency of international normalized ratio (INR) monitoring with a conventional laboratory test in stable patients is once a month. When using a dedicated personal device for INR assessment, the frequency may be increased to two or more times a month.
Objective: To show that INR assessed by self-measurement at home is reliable and feasible in the mid-term and improves medical care.
Patients and methods: All patients in the study on INR self-measurement (clinical trial.gov: NCT00925197), conducted between 2004 and 2007, were re-contacted for mid-term follow-up. One hundred and seventy eight out of 192 patients who participated in the study answered a questionnaire. The average follow-up time was 4.2 years (±1) for the self-measurement group and 4.9 years (±1) for the laboratory-analyzed control group.
Results: Only 26 patients (group A) continued to use INR self-measurement to monitor treatment with vitamin K antagonists (VKA). The main reasons to stop INR self-measurement were its high cost and difficulty in obtaining strips. There were significantly fewer bleeding complications (p=0.04) and complications related to VKA (p=0.01) in self-measured patients compared to the control group. Feelings of security and quality of life were also significantly better (p=0.002) for self-measured patients.
Conclusion: Many patients with a mechanical heart valve, who self-measured INR, continue to use this method for their follow-up because of its positive effects on their health and quality of life.
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