Determinants of oral anticoagulation control in new warfarin patients: analysis using data from Clinical Practice Research Datalink.

BACKGROUND: The safety and effectiveness of warfarin therapy depends critically on the quality of anticoagulation control, often assessed using the percentage time in therapeutic International Normalised Ratio (INR) range (TTR). We aimed to identify patient characteristics related to anticoagulation control with warfarin, measured by TTR. METHOD: We carried out a population-based study using the Clinical Practice Research Datalink, including two cohorts of patients starting warfarin after a first diagnosis of atrial fibrillation (AF) or venous thromboembolism (VTE) between 2000 and 2013. We used multivariate mixed regression and logistic regression models to predict the fully-adjusted effect of each predictor variable upon TTR. RESULTS: The study population comprised 29,717 incident AF and 19,113 incident VTE patients who initiated warfarin. In real world clinical practice a minority of patients achieve good anticoagulation control with warfarin (44% AF and 36% VTE patients had TTR≥70%). Poor anticoagulation control driven by subtherapeutic INRs was observed in younger patients (<45years) and in AF patients with increased number of hospitalisations. Poor anticoagulation control driven by sub and/or supratherapeutic INRs was seen in AF and VTE patients current smokers, in patients using medications for pain and in VTE patients with active cancer. CONCLUSION: In a real world clinical practice there is a high amount of unpredictable inter-individual TTR variability and in some patients good anticoagulation control is more challenging than in others. These findings may help to identify patients who will require closer monitoring or innovative strategies to optimise the outcomes of oral anticoagulant therapy.

How reliable are stroke patients' reports of their numbers of general practice consultations over 12 months?

BACKGROUND: Data on primary health care use are frequently used in economic evaluations. However, it is unclear how patient self-reports of their number of consultations with their general practitioner (GP) relate to actual consultations in the electronic records. These data are crucial if self-reports are used to conduct economic evaluations. OBJECTIVES: To report the accuracy of stroke patients' self-reports of their number of primary care consultations over a 12-month period by comparison with practice-held electronic records. We also recorded the number of contacts required to collect service use data from the practices. METHODS: We contacted 65 practices requesting electronic consultation records over 12 months for 115 stroke patients who took part in a trial of home blood pressure monitoring. Consultation rates from the electronic records were compared with patients' self-reported number of consultations from a questionnaire covering the same period. RESULTS: Fifty-one practices (78%) responded. Patients' questionnaires (n = 83) reported a mean of 5.7 consultations with their GP per year compared with 7.2 in the electronic records (difference 1.6, 95% confidence interval 0.5-2.7, P < 0.01). The mean time taken to obtain records from practices was 6 weeks. CONCLUSIONS: Patients modestly under-reported the number of consultations they had with a GP. Obtaining patient records from practices required more effort than obtaining information from patient questionnaires at the same time as assessing main trial outcomes. If patient self-reports of health care usage are used in economic evaluations in primary care, researchers should consider validating a sample against electronic records.

Community based trial of home blood pressure monitoring with nurse-led telephone support in patients with stroke or transient ischaemic attack recently discharged from hospital.

BACKGROUND: High blood pressure in patients with stroke increases the risk of recurrence but management in the community is often inadequate. Home blood pressure monitoring may increase patients' involvement in their care, increase compliance, and reduce the need for patients to attend their General Practitioner if blood pressure is adequately controlled. However the value of home monitoring to improve blood pressure control is unclear. In particular its use has not been evaluated in stroke patients in whom neurological and cognitive ability may present unique challenges. DESIGN: Community based randomised trial with follow up after 12 months. PARTICIPANTS: 360 patients admitted to three South London Stroke units with stroke or transient ischaemic attack within the past 9 months will be recruited from the wards or outpatients and randomly allocated into two groups. All patients will be visited by the specialist nurse at home at baseline when she will measure their blood pressure and administer a questionnaire. These procedures will be repeated at 12 months follow up by another researcher blind as to whether the patient is in intervention or control group. INTERVENTION: INTERVENTION patients will be given a validated home blood pressure monitor and support from the specialist nurse. Control patients will continue with usual care (blood pressure monitoring by their practice). Main outcome measures in both groups after 12 months: 1. Change in systolic blood pressure.2. Cost effectiveness: Incremental cost of the intervention to the National Health Service and incremental cost per quality adjusted life year gained. TRIAL REGISTRATION: Clinical Trials.gov registration NCT00514800.