A systematic review of outcome measures reported for the therapeutic effectiveness of oral anticoagulation.

AIMS: To evaluate the evidence of therapeutic international normalised ratio (INR) control reporting and to provide recommendations for future reporting, particularly for research and audit purposes. METHODS: A systematic review of literature published over a five year period describing therapeutic INR control. Papers were identified from the Medline electronic database, and those that met the quality criteria were reviewed independently by an academic general practitioner and a consultant haematologist. RESULTS: Fifteen papers were identified that met the quality criteria for review. The sample size of studies ranged from 53 to 2545 (mean, 483.9) patients. Follow up ranged from three months to 13 years. Twelve studies reported results from secondary care only, one from primary care only, and two from both primary and secondary care. Seven of the 15 papers reported percentage time in range, five of 15 papers reported mean INR, six of 15 papers reported the proportion of tests in range, and five of 15 papers reported mean warfarin dose. Additional methods of presenting INR results were: dose changes each month, distribution of INR results, deviation of INR value from mean, percentage dose changes, time between visits, and median INR value. Six papers reported only one outcome measure, six reported two outcomes, two papers reported three outcomes, and one paper reported five outcomes. CONCLUSIONS: It is recommended that at least two outcome measures should be reported and measures should be selected so that both the INR determinations and dosing advice are monitored.

A randomised controlled trial of patient self management of oral anticoagulation treatment compared with primary care management.

BACKGROUND: The increase in numbers of patients receiving warfarin treatment has led to the development of alternative models of service delivery for oral anticoagulant monitoring. Patient self management for oral anticoagulation is a model new to the UK. This randomised trial was the first to compare routine primary care management of oral anticoagulation with patient self management. AIM: To test whether patient self management is as safe, in terms of clinical effectiveness, as primary care management within the UK, as assessed by therapeutic international normalised ratio (INR) control. METHOD: Patients receiving warfarin from six general practices who satisfied study entry criteria were eligible to enter the study. Eligible patients were randomised to either intervention (patient self management) or control (routine primary care management) for six months. The intervention comprised two training sessions of one to two hours duration. Patients were allowed to undertake patient self management on successful completion of training. INR testing was undertaken using a Coaguchek device and regular internal/external quality control tests were performed. Patients were advised to perform INR tests every two weeks, or weekly if a dose adjustment was made. Dosage adjustment was undertaken using a simple dosing algorithm. RESULTS: Seventy eight of 206 (38%) patients were eligible for inclusion and, of these, 35 (45%) declined involvement or withdrew from the study. Altogether, 23 intervention and 26 control patients entered the study. There were no significant differences in INR control (per cent time in range: intervention, 74%; control, 77%). There were no serious adverse events in the intervention group, with one fatal retroperitoneal haemorrhage in the control group. Costs of patient self management were significantly greater than for routine care (pound 90 v pound 425/patient/year). CONCLUSION: These are the first UK data to demonstrate that patient self management is as safe as primary care management for a selected population. Further studies are needed to elucidate whether this model of care is suitable for a larger population.

Does the Birmingham model of oral anticoagulation management in primary care work outside trial conditions?

The effectiveness of the Birmingham model of primary care oral anticoagulation management has previously been demonstrated within a randomised controlled trial. The aim of this study was to assess the effectiveness of the Birmingham model in routine care. All patients from 12 primary care centres attending either practice-based or hospital-based anticoagulation clinics were retrospectively followed up from October 1996 to March 1998. Outcome measures were therapeutic International Normalised Ratio (INR) control, haemorrhagic and thrombotic episodes, and recall frequency; 452 patients who had two or more INR results during the follow-up period were investigated. There were no significant differences between practice-based and hospital-based populations in terms of the percentage time in range, (69% and 64% respectively). The proportion of tests in range was significantly higher in the practice-based group (61% practice-based, 57% hospital-based; P = 0.015). There was no difference between the two populations in terms of mean follow-up time (36 days in each group). There were no significant differences between groups for the number of clinical outcomes per patient. This study confirmed that, within these practices, oral anticoagulation management is safe and effective using the Birmingham model.