Quality assurance for oral anticoagulation self management: a cluster randomized trial

Background and aims: External quality assessment (EQA) should be an inherent component of patient self management (PSM) of oral anticoagulation. The aim of this study was to evaluate methods of EQA for patients within a cluster randomized trial. Method: After development of methods, general practises were randomly allocated to a formal EQA scheme of patients performing the test independently at home or at their practise with supervision. The supervised group of practises was further sub divided to test two other EQA methods: (i) venous sample compared with patients' point of care (POC) device; and (ii) patients POC compared with reference POC. Primary trial outcome measure was reliability of results from the formal scheme taking into account adherence and test errors. Results: Proportion of EQA scheme tests in range was 633/836 (75.7%). Proportion in range was significantly higher in group performing independently compared with supervised group, 80.1% vs. 71.5% respectively, P = 0.02. Sixty-six percent of tests were in range with venous compared with patients POC, and 88% in patients POC compared with reference POC. Conclusion: Patients are able to undertake a formal EQA scheme and perform more reliably at home independently. There are satisfactory alternatives if a formal scheme is not acceptable.