INRs and point of care testing.
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Biomedical subjects
Publications and source records attributed to E T Murray.
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The role of external quality assessment (EQA) is a contentious issue for patient self-management (PSM) of oral anticoagulation. Patients from general practices in the West Midlands undertaking PSM were recruited to compare efficacy of patients' and health professionals' EQA procedure using the UK National External Quality Assessment Scheme (NEQAS). Patients using Coaguchek (Roche Diagnostics) were trained to perform EQA as part of their PSM training. They undertook PSM for 26 weeks and were asked to perform EQA using material provided by the UK NEQAS twice at home without supervision and twice at the practice with supervision. Patients' results were compared with health care professional users of Coaguchek S. Twenty-three PSM patients were compared with 75 health care professional users of the NEQAS scheme. The PSM group international normalized ratio (INR) percentage time in range was 74%. There was no significant difference in the median results on NEQAS samples obtained by the patients and those obtained by professionals. Three patients were outwith consensus (results > 15% from the median INR) on more than one occasion. Patients were able to perform the EQA tests competently. The data show that good agreement can be achieved between patients analysing the same EQA samples, with coefficients of variation ranging from 22.3% to as low as 5.4%. Further study is required to determine how precision within these EQA schemes relates to the stability of treatment in patients' management of their own 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.
AIM: To establish and evaluate an external quality assessment scheme for warfarin dosing for users of a computerised decision support system, BAP-PC. DESIGN: Analysis of 12 months of clinical data from 10 primary care centres using BAP-PC within an oral anticoagulation clinic. Data were analysed for individual centres and compared with aggregated data for all practices. Individual feedback forms were provided to participating centres. RESULTS: A total patient population of 367 (range, 17-65/centre) was analysed. On average, patients spent 69% of time in the therapeutic range (range, 60-76%). Patients were seen on average every 27 days (range, 24-30). The average point prevalence was 86% (range, 76-100%). In total, 33 adverse events were reported (0-13/practice). Serious adverse events ranged from 0 to 1 for each practice. This translates into a serious adverse event rate of 1.6/100 patient years. CONCLUSIONS: Practices were successful in maintaining good therapeutic international normalised ratio control, with centres achieving 60% or higher time in range. There are some doubts about the quality of data collection at a practice level because there were no reported events in half of the participating centres. The observed event rates do concur with previously reported data, however. Further cycles of the scheme are necessary to establish it as a useful research and benchmarking tool.
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.
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.
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OBJECTIVE: To assess the prevalence, amount, and duration of use of vaginal estrogen cream among several birth cohorts of women from 1983 through 1992. DESIGN: Analyses are based on automated membership, pharmacy, and hospital discharge databases from Group Health Cooperative (GHC) of Puget Sound, a large health maintenance organization in Seattle, Washington. PARTICIPANTS: A total of 33,822 women, aged 45 years and older as of December 31, 1983, who were enrolled in GHC from 1983 to 1992 or who were enrolled at baseline and died in the following decade. RESULTS: About 24% of the cohort had filled at least one prescription for vaginal estrogen cream during 1983 through 1992, and about 60% of the users had more than one prescription filled. The annual birth cohort-specific prevalence of having filled one or more prescriptions for vaginal estrogen creams ranged between 1.6 and 8.2% across birth cohorts, whereas the average annual prevalence for the cohort was between 5.3 and 6.8%. The total amount, duration of use, and proportion of total estrogen exposure from creams increased with age of the birth cohort. Among the 733 women with intact uteri who were long-term cream users, 60.4% had no progestin prescriptions while averaging 22.1 tubes of estrogen cream. CONCLUSION: The prescription-filling patterns for estrogen in this cohort show an increase in the amount, years of use, and proportion of estrogen exposure from creams with the age of the birth cohort and extensive unopposed cream use among a small proportion of women with intact uteri. The systemic effects of vaginal estrogen cream among older postmenopausal women with urogenital atrophy deserve closer scrutiny.
AIM: To compare the reliability and relative costs of three international normalised ratio (INR) near patient tests. MATERIALS: Protime (ITC Technidyne), Coaguchek (Boehringer Mannheim), and TAS (Diagnostic Testing). METHODS: All patients attending one inner city general practice anticoagulation clinic were asked to participate, with two samples provided by patients not taking warfarin. A 5 ml sample of venous whole blood was taken from each patient and a drop immediately added to the prepared Coaguchek test strip followed by the Protime cuvette. The remainder was added to a citrated bottle. A drop of citrated blood was then placed on the TAS test card and the remainder sent to the reference laboratory for analysis. Parallel INR estimation was performed on the different near patient tests at each weekly anticoagulation clinic from July to December 1997. RESULTS: 19 patients receiving long term warfarin treatment provided 62 INR results. INR results ranged from 0.8-8.2 overall and 1.0-5.7 based on the laboratory method. Taking the laboratory method as the gold standard, 12/62 results were < 2.0 and 2/62 were > 4.5. There were no statistical or clinically significant differences between results from the three systems, although all near patient tests showed slightly higher mean readings than the laboratory, and 19-24% of tests would have resulted in different management decisions based on the machine used in comparison with the laboratory INR value. The cost of the near patient test systems varied substantially. CONCLUSIONS: All three near patient test systems are safe and efficient for producing acceptable and reproducible INR results within the therapeutic range in a primary care setting. All the systems were, however, subject to operator dependent variables at the time of blood letting. Adequate training in capillary blood sampling, specific use of the machines, and quality assurance procedures is therefore essential.
AIM: To determine the reliability of international normalised ratio (INR) measurement in primary care by practice nurses using near patient testing (NPT), in comparison with results obtained within hospital laboratories by varied methods. METHODS: As part of an MRC funded study into primary care oral anticoagulation management, INR measurements obtained in general practice were validated against values on the same samples obtained in hospital laboratories. A prospective comparative trial was undertaken between three hospital laboratories and nine general practices. All patients attending general practice based anticoagulant clinics had parallel INR estimations performed in general practice and in a hospital laboratory. RESULTS: 405 tests were performed. Comparison between results obtained in the practices and those in the reference hospital laboratory (gold standard), which used the same method of testing for INR, showed a correlation coefficient of 0.96. Correlation coefficients comparing the results with the various standard laboratory techniques ranged from 0.86 to 0.92. It was estimated that up to 53% of tests would have resulted in clinically significant differences (change in warfarin dose) depending upon the site and method of testing. The practice derived results showed a positive bias ranging from 0.28 to 1.55, depending upon the site and method of testing. CONCLUSIONS: No technical problems associated with INR testing within primary care were uncovered. Discrepant INR results are as problematic in hospital settings as they are in primary care. These data highlight the failings of the INR to standardise when different techniques and reagents are used, an issue which needs to be resolved. For primary care to become more involved in therapeutic oral anticoagulation monitoring, close links are needed between hospital laboratories and practices, particularly with regard to training and quality assurance.
BACKGROUND: Increasing indications for warfarin therapy has led to increased pressure on primary care to undertake therapeutic monitoring. OBJECTIVE: This study evaluates a primary care model of oral anticoagulation monitoring which utilises computerized decision support (CDSS) and near patient testing (NPT) within a practice nurse-led clinic. Whilst this has been shown to be a successful model under trial conditions, this paper reports the first data from a long-standing clinic, outside a formal study. METHOD: A prospective evaluation of therapeutic and clinical control of all patients taking warfarin within one inner city general practice. Data were collected via CDSS. RESULTS: 29 patients were seen in 208 appointments. The mean percentage of patients within therapeutic range was 72%. The costs to the practice were pound sterling 1751. The costs the practice would have incurred had these patients been seen at the hospital with the same frequency would have been pound sterling 2290. CONCLUSIONS: The use of CDSS and NPT for nurse-delivered oral anticoagulation monitoring could enable the safe transfer of the majority of patients from secondary to primary care. Funding mechanisms to support the transfer of costs will be essential for most practices, as will be the maintenance of adequate staff training and quality assurance.
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Near patient activity is now increasing within the United Kingdom and can be a valuable activity within primary care, but only within the confines of safe practice that incorporates quality control procedures. This study identified widespread use of near patient testing (NPT) within primary care but that there is a haphazard approach to specific test performance. Results showed a poor understanding of quality control issues and provide a clear indication of future training and educational priorities if NPT is to develop in primary care.
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BACKGROUND: Increasing indications for oral anticoagulation has led to pressure on general practices to undertake therapeutic monitoring. Computerized decision support (DSS) has been shown to be effective in hospitals for improving clinical management. Its usefulness in primary care has previously not been investigated. AIM: To test the effectiveness of using DSS for oral anticoagulation monitoring in primary care by measuring the proportions of patients adequately controlled, defined as within the appropriate therapeutic range of International Normalised Ratio (INR). METHOD: All patients receiving warfarin from two Birmingham inner city general practices were invited to attend a practice-based anticoagulation clinic. In practice A all patients were managed using DSS. In practice B patients were randomized to receive dosing advice either through DSS or through the local hospital laboratory. Clinical outcomes, adverse events and patient acceptability were recorded. RESULTS: Forty-nine patients were seen in total. There were significant improvements in INR control from 23% to 86% (P > 0.001) in the practice where all patients received dosing through DSS. In the practice where patients were randomized to either DSS or hospital dosing, logistic regression showed a significant trend for improvement in intervention patients which was not apparent in the hospital-dosed patients (P < 0.001). Mean recall times were significantly extended in patients who were dosed by the practice DSS through the full 12 months (24 days to 36 days) (P = 0.033). Adverse events were comparable between hospital and practice-dosed patients, although a number of esoteric events occurred. Patient satisfaction with the practice clinics was high. CONCLUSION: Computerized DSS enables the safe and effective transfer of anticoagulation management from hospital to primary care and may result in improved patient outcome in terms of the level of control, frequency of review and general acceptability.