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1.  Safety and effectiveness of point-of-care monitoring devices in patients on oral anticoagulant therapy: a meta-analysis 
Open Medicine  2007;1(3):e131-e146.
Point-of-care devices (POCDs) for monitoring long-term oral anticoagulation therapy (OAT) may be a useful alternative to laboratory-based international normalized ratio [INR] testing and clinical management.
To determine clinical outcomes of the use of POCDs for OAT management by performing a meta-analysis. Previous meta-analyses on POCDs have serious limitations.
Data sources
PubMed, the Cochrane Library, DIALOG, MEDLINE, EMBASE, BIOSIS Previews and PASCAL databases.
Study selection
Randomized controlled trials of patients on long-term OAT, comparing anticoagulation monitoring by POCD with laboratory INR testing and clinical management.
Data extraction
1) rates of major hemorrhage; 2) rates of major thromboembolic events; 3) percentage of time that the patient is maintained within the therapeutic range; 4) deaths. Outcomes were compared using a random-effects model. Summary measures of rates were determined. The quality of studies was assessed using the Jadad scale.
Data synthesis
Seventeen articles (16 studies) were included. Data analysis showed that POCD INR testing reduced the risk of major thromboembolic events (odds ratio [OR] = 0.51; 95% confidence interval [CI] 0.35–0.74), was associated with fewer deaths (OR = 0.58; 95% CI = 0.38–0.89), and resulted in better INR control compared with laboratory INR testing. No significant difference between the two management modalities with respect to odds ratios for major hemorrhage was found.
Quality scores varied from 1 to 3 (out of a maximum of 5). Only 3 studies defined how thromboembolic events would be diagnosed, casting doubt on the accuracy of the reporting of thromboembolic events. The studies suggest that only 24% of patients are good candidates for self-testing and self-management. Compared with patients managed with laboratory-based monitoring, POCD patients underwent INR testing at a much higher frequency and received much more intensive education on OAT management.
The use of POCDs is safe and may be more effective than laboratory-based monitoring. However, most patients are not good candidates for self-testing and self-management. Patient education and frequency of testing may be the most important factors in successful PODC management. Definitive conclusions about the clinical benefits provided by self-testing and self-management require more rigorously designed trials.
PMCID: PMC3113217  PMID: 21673942
2.  Patient self-management of warfarin therapy 
Canadian Family Physician  2011;57(8):e292-e298.
To investigate the effectiveness of patient self-management (PSM) of anticoagulation using warfarin in a typical primary care site in Canada and to determine the feasibility of conducting a future large-scale trial in this setting.
An 8-month pragmatic open-label randomized crossover trial.
A typical Canadian primary care practice in British Columbia.
Patients were randomized to PSM or physician management for 4 months, after which allocation was reversed. The PSM group members were instructed to monitor their serum international normalized ratio (INR) at community laboratories and to adjust their warfarin doses independently using provided nomograms. Education on warfarin dose adjustment was limited to a single 15-minute office visit.
Main outcome measures
The primary outcome was the proportion of INR values in the therapeutic range among participants. Feasibility outcomes included proportion of eligible patients consenting, patients’ preference of management strategy, patients’ satisfaction, and visits or phone communication with physicians regarding dose adjustment. Safety outcomes included bleeding or thromboembolic events.
Eleven patients completed the trial, contributing 99 patient-months of monitoring and providing 122 INR measures. The mean proportion of INR values in therapeutic range among subjects in the PSM and physician-management groups was 82% and 80%, respectively (P = .82). The improvement in patient satisfaction with PSM was not significant. Ten of the 11 patients preferred PSM to physician management and elected to continue with this strategy after study completion (P = .001). No calls or visits were made to the physician regarding dose adjustment during the PSM period. There were no episodes of major bleeding or thromboembolic events.
Patient self-management was not demonstrated to be superior to standard care, but was easily implemented and was the method preferred by patients. Our feasibility outcomes justify a larger trial and suggest that subject recruitment and protocol adherence would not pose barriers for such a study.
Trial registration number
NCT00925028 (
PMCID: PMC3155464  PMID: 21841092
3.  Supervised Patient Self-Testing of Warfarin Therapy Using an Online System 
Point-of-care international normalized ratio (INR) monitoring devices simplify warfarin management by allowing selected patients to monitor their own therapy in their homes. Patient self-testing (PST) has been shown to improve the clinical outcomes of warfarin therapy compared to usual care.
To compare management of warfarin therapy using PST combined with online supervision by physicians via a custom system with usual warfarin management, which involved laboratory testing and physician dosing.
Interested patients were recruited via community pharmacies to participate in a warfarin PST training program. Participants were required to have a long-term indication for warfarin, have been taking warfarin for at least 6 months, and have Internet access in their home. The training involved two sessions covering theoretical aspects of warfarin therapy, use of the CoaguChek XS, and the study website. Following training, patients monitored their INR once weekly for up to 3 months. Patients and physicians utilized a secure website to communicate INR values, dosage recommendations, and clinical incidents. Physicians provided a 6-12 month history of INR results for comparison with study results. The percentage of time spent within the therapeutic INR range (TTR) was the primary outcome, with participants acting as their own historical controls. The percentage of INR tests in range and participant satisfaction were secondary outcomes.
Sixteen patients completed training requirements. The mean age of participants was 69.8 (SD 10.1) years. TTR improved significantly from 66.4% to 78.4% during PST (P=.01), and the number of tests within the target range also improved significantly (from 66.0% at prior to the study to 75.9% during PST; P=.04). Patients and physicians expressed a high degree of satisfaction with the monitoring strategy and online system.
PST supported by an online system for supervision was associated with improved INR control compared to usual care in a small group of elderly patients. Further research is warranted to investigate the clinical outcomes and cost-effectiveness of online systems to support patients monitoring medications and chronic conditions in the home.
PMCID: PMC3713938  PMID: 23853350
warfarin; self-care; management; international normalized ratio; Internet; communication
4.  The Clinical Impact of Different Coagulometers on Patient Outcomes 
Advances in Therapy  2014;31(6):639-656.
Long-term anticoagulation therapy using vitamin K antagonists (VKA) is used in millions of patients worldwide to reduce the risk of thrombotic or thromboembolic events. Control and monitoring of VKA therapy is improved by the regular self-measurement of international normalized ratio (INR) using a home monitoring device. This retrospective analysis of a large cohort of patients in the Netherlands seeks to determine whether the choice of INR monitor could have a clinical impact on patient outcomes.
The National Thrombosis Service provides medical supervision, training and support to anticoagulant patients eligible for home-monitoring of INR in the Netherlands. Two INR monitors (CoaguChek XS and INRatio2) have been distributed at random to patients since June 2011, and patient self-testing data (INR measurements and other clinical parameters) have been recorded to measure and improve treatment outcomes. The data have been retrospectively analyzed to determine any effect of the choice of monitor. Univariate and multivariate statistical tests are used to assess any differences between groups in terms of efficacy and safety parameters.
Data from 4,326 patients were collated, and 156,507 INR values were included in the analysis. Over half the patients (54.3%) were being treated for atrial fibrillation, and 77.6% were prescribed acenocoumarol. There were few differences between the patient populations using the two different monitors. Anticoagulant control overall was good, with high percentage of time (87.9%) in the appropriate INR range and low incidence of excessively high or low INR values (0.085/month). Minor clinical events related to safety were low (0.78 per patient-year) and showed few differences between monitors. Mortality rates were similar [hazard ratio (HR) 1.05, 95% confidence interval (CI) 0.65–1.70].
Self-testing data from a large cohort of patients in the Netherlands suggest that there is no clinically relevant effect of the choice of coagulation monitor (CoaguChek XS or INRatio2) on the time in therapeutic range (TTR), minor or fatal outcomes of long-term anticoagulation management.
Electronic supplementary material
The online version of this article (doi:10.1007/s12325-014-0124-x) contains supplementary material, which is available to authorized users.
PMCID: PMC4082646  PMID: 24895179
Anticoagulation; CoaguChek XS; INRatio2; International normalized ratio (INR); Patient self-monitoring (PSM); Patient self-testing (PST); Point of care (POC) test (POCT); Time in therapeutic range (TTR); Time in target range; Vitamin K antagonist (VKA)
5.  A role for pharmacists in community-based post-discharge warfarin management: protocol for the 'the role of community pharmacy in post hospital management of patients initiated on warfarin' study 
Shorter periods of hospitalisation and increasing warfarin use have placed stress on community-based healthcare services to care for patients taking warfarin after hospital discharge, a high-risk period for these patients. A previous randomised controlled trial demonstrated that a post-discharge service of 4 home visits and point-of-care (POC) International Normalised Ratio (INR) testing by a trained pharmacist improved patients' outcomes. The current study aims to modify this previously trialled service model to implement and then evaluate a sustainable program to enable the smooth transition of patients taking warfarin from the hospital to community setting.
The service will be trialled in 8 sites across 3 Australian states using a prospective, controlled cohort study design. Patients discharged from hospital taking warfarin will receive 2 or 3 home visits by a trained 'home medicines review (HMR)-accredited' pharmacist in their 8 to 10 days after hospital discharge. Visits will involve a HMR, comprehensive warfarin education, and POC INR monitoring in collaboration with patients' general practitioners (GPs) and community pharmacists. Patient outcomes will be compared to those in a control, or 'usual care', group. The primary outcome measure will be the proportion of patients experiencing a major bleeding event in the 90 days after discharge. Secondary outcome measures will include combined major bleeding and thromboembolic events, death, cessation of warfarin therapy, INR control at 8 days post-discharge and unplanned hospital readmissions from any cause. Stakeholder satisfaction will be assessed using structured postal questionnaire mailed to patients, GPs, community pharmacists and accredited pharmacists at the completion of their study involvement.
This study design incorporates several aspects of prior interventions that have been demonstrated to improve warfarin management, including POC INR testing, warfarin education and home visits by trained pharmacists. It faces several potential challenges, including the tight timeframe for patient follow-up in the post-discharge period. Its strengths lie in a strong multidisciplinary team and the utilisation of existing healthcare frameworks. It is hoped that this study will provide the evidence to support the national roll-out of the program as a new Australian professional community pharmacy service.
Trial Registration
Australian New Zealand Clinical Trials Registry Number 12608000334303.
PMCID: PMC3040704  PMID: 21261998
6.  A Pharmacist-Led Point-of-Care INR Clinic: Optimizing Care in a Family Health Team Setting 
Purpose. Monitoring patients' international normalized ratio (INR) within a family medicine setting can be challenging. Novel methods of doing this effectively and in a timely manner are important for patient care. The purpose of this study was to determine the effectiveness of a pharmacist-led point-of-care (POC) INR clinic. Methods. At a community-based academic Family Health Team in Toronto, Canada, charts of patients with atrial fibrillation managed by a pharmacist with usual care (bloodtesting at lab and pharmacist follow up of INR by phone) from February 2008 to April 2008 were compared with charts of patients attending a weekly POC INR clinic from February 2010 to April 2010. Time in therapeutic range (TTR) was measured for both groups. Results. 119 patient charts were reviewed and 114 had TTR calculated. After excluding patients with planned inconsistent Coumadin use (20), such as initiating Coumadin treatment or stopping for a surgical procedure, the mean TTR increased from 64.41% to 77.09% with the implementation of the POC clinic. This was a statistically significant difference of 12.68% (CI: 1.18, 24.18; P = 0.03). Conclusion. A pharmacist-led POC-INR clinic improves control of anticoagulation therapy in patients receiving warfarin and should be considered for implementation in other family medicine settings.
PMCID: PMC3876693  PMID: 24455250
7.  A team-based approach to warfarin management in long term care: A feasibility study of the MEDeINR electronic decision support system 
BMC Geriatrics  2010;10:38.
Previous studies in long-term care (LTC) have demonstrated that warfarin management is suboptimal with preventable adverse events often occurring as a result of poor International Normalized Ratio (INR) control. To assist LTC teams with the challenge of maintaining residents on warfarin in the therapeutic range (INR of 2.0 to 3.0), we developed an electronic decision support system that was based on a validated algorithm for warfarin dosing. We evaluated the MEDeINR system in a pre-post implementation design by examining the impact on INR control, testing frequency, and experiences of staff in using the system.
For this feasibility study, we piloted the MEDeINR system in six LTC homes in Ontario, Canada. All128 residents (without a prosthetic valve) who were taking warfarin were included. Three-months of INR data prior to MEDeINR was collected via a retrospective chart audit, and three-months of INR data after implementation of MEDeINR was captured in the central computer database. The primary outcomes compared in a pre-post design were time in therapeutic range (TTR) and time in sub/supratherapeutic ranges based on all INR measures for every resident on warfarin. Secondary measures included the number of monthly INR tests/resident and survey/focus-group feedback from the LTC teams.
LTC homes in our study had TTR's that were higher than past reports prior to the intervention. Overall, the TTR increased during the MEDeINR phase (65 to 69%), but was only significantly increased for one home (62% to 71%, p < 0.05). The percentage of time in supratherapeutic decreased from 14% to 11%, p = 0.08); there was little change for the subtherapeutic range (21% to 20%, p = 0.66). Overall, the average number of INR tests/30 days decreased from 4.2 to 3.1 (p < 0.0001) per resident after implementation of MEDeINR. Feedback received from LTC clinicians and staff was that the program decreased the work-load, improved confidence in management and decisions, and was generally easy to use.
Although LTC homes in our sample had TTR's that were relatively high prior to the intervention, the MEDeINR program represented a useful tool to promote optimal TTR, decrease INR venipunctures, streamline processes, and increase nurse and physician confidence around warfarin management. We have demonstrated that MEDeINR was a practical, usable clinical information system that can be incorporated into the LTC environment.
PMCID: PMC2902482  PMID: 20537178
8.  Evaluation of patient perceptions and outcomes related to anticoagulation point-of-care testing in ambulatory care clinics 
Pharmacy Practice  2009;7(4):213-217.
Until recently, Prothrombin Time/International Normalized Ratio (PT/INR) measurements have typically been used to monitor patients on warfarin through institutional laboratories via venous puncture. The Point-of-Care Testing (POCT) device has revolutionized the patient care process by allowing for laboratory testing outside of the central laboratory.
To analyze humanistic and clinical outcomes in patients currently treated with warfarin and monitored through a pharmacist-managed anticoagulation clinic using point-of-care testing (POCT) device versus venipuncture within ambulatory care clinics at our institution.
All patients currently treated with warfarin therapy who were managed by clinical pharmacists for anticoagulation monitoring at the Medical University of South Carolina (MUSC) Family Medicine Center and University Diagnostic Center, were enrolled. Patients were asked to complete a satisfaction survey regarding their anticoagulation monitoring. In addition, data related to emergency department (ED) visits, hospitalizations and percent of time in the INR therapeutic range for 6 months pre- and post-implementation of POCT device was collected. This information was obtained through an electronic patient information database, Oacis.
A total of 145 patients were included in the data collection from the two clinics. The majority (41%) of these patients were taking warfarin for atrial fibrillation. Satisfaction surveys were completed by 86 (59 %) of patients. The surveys revealed that POCT device was preferred over venipuncture in 95% of patients. Reasons for the preference included more face-to-face interaction, less wait time, less pain, less blood needed, and quicker results. Of the 145 patients who were included in the objective data analysis, no significant differences were found in the number of hospitalizations, ED visits, or percent of time in the INR therapeutic range pre- and post-implementation of POCT device.
The results of this study demonstrate improvement in patient satisfaction with POCT compared to venipuncture, with limited value in clinical outcomes.
PMCID: PMC4134839  PMID: 25136396
Point-of-Care Systems; Patient Satisfaction; Pharmaceutical Services; United States
9.  Patients' perspectives on self-testing of oral anticoagulation therapy: Content analysis of patients' internet blogs 
Patients on oral anticoagulant therapy (OAT) require regular testing of the prothrombin time (PT) and the international normalised ratio (INR) to monitor their blood coagulation level to avoid complications of either over or under coagulation. PT/INR can be tested by a healthcare professional or by the patient. The latter mode of the testing is known as patient self-testing or home testing. The objective of this study was to elicit patients' perspectives and experiences regarding PT/INR self-testing using portable coagulometer devices.
Internet blog text mining was used to collect 246 blog postings by 108 patients, mainly from the USA and the UK. The content of these qualitative data were analysed using XSight and NVivo software packages.
The key themes in relation to self-testing of OAT identified were as follows: Patient benefits reported were time saved, personal control, choice, travel reduction, cheaper testing, and peace of mind. Equipment issues included high costs, reliability, quality, and learning how to use the device. PT/INR issues focused on the frequency of testing, INR fluctuations and individual target (therapeutic) INR level. Other themes noted were INR testing at laboratories, the interactions with healthcare professionals in managing and testing OAT and insurance companies' involvement in acquiring the self-testing equipment. Social issues included the pain and stress of taking and testing for OAT.
Patients' blogs on PT/INR testing provide insightful information that can help in understanding the nature of the experiences and perspectives of patients on self-testing of OAT. The themes identified in this paper highlight the substantial complexities involved in self-testing programmes in the healthcare system. Thus, the issues elicited in this study are very valuable for all stakeholders involved in developing effective self-testing strategies in healthcare that are gaining considerable current momentum particularly for patients with chronic illness.
PMCID: PMC3045880  PMID: 21291542
10.  Comparing the quality of oral anticoagulant management by anticoagulation clinics and by family physicians: a randomized controlled trial 
There is growing evidence that better outcomes are achieved when anticoagulation is managed by anticoagulation clinics rather than by family physicians. We carried out a randomized controlled trial to evaluate these 2 models of anticoagulant care.
We randomly allocated patients who were expected to require warfarin sodium for 3 months either to anticoagulation clinics located in 3 Canadian tertiary hospitals or to their family physician practices. We evaluated the quality of oral anticoagulant management by comparing the proportion of time that the international normalized ratio (INR) of patients receiving warfarin sodium was within the target therapeutic range ± 0.2 INR units (expanded therapeutic range) while they were managed in anticoagulation clinics as opposed to family physicians' care over 3 months. We measured the rates of thromboembolic and major hemorrhagic events and patient satisfaction in the 2 groups.
Of the 221 patients enrolled, 112 were randomly assigned to anticoagulation clinics and 109 to family physicians. The INR values of patients who were managed by anticoagulation clinics were within the expanded therapeutic range 82% of the time versus 76% of the time for those managed by family physicians (p = 0.034). High-risk INR values (defined as being < 1.5 or > 5.0) were more commonly observed in patients managed by family physicians (40%) than in patients managed by anticoagulation clinics (30%, p = 0.005). More INR measurements were performed by family physicians than by anticoagulation clinics (13 v. 11, p = 0.001). Major bleeding events (2 [2%] v. 1 [1%]), thromboembolic events (1 [1%] v. 2 [2%]) and deaths (5 [4%] v. 6 [6%]) occurred at a similar frequency in the anticoagulation clinic and family physician groups respectively. Of the 170 (77%) patients who completed the patient satisfaction questionnaire, more were satisfied when their anticoagulant management was managed through anticoagulation clinics than by their family physicians (p = 0.001).
Anticoagulation clinics provided better oral anticoagulant management than family physicians, but the differences were relatively modest.
PMCID: PMC180652  PMID: 12925422
11.  Quality of vitamin K antagonist control and outcomes in atrial fibrillation patients: a meta-analysis and meta-regression 
Thrombosis Journal  2014;12:14.
Atrial fibrillation (AF) patients frequently require anticoagulation with vitamin K antagonists (VKAs) to prevent thromboembolic events, but their use increases the risk of hemorrhage. We evaluated time spent in therapeutic range (TTR), proportion of international normalized ratio (INR) measurements in range (PINRR), adverse events in relation to INR, and predictors of INR control in AF patients using VKAs.
We searched MEDLINE, CENTRAL and EMBASE (1990-June 2013) for studies of AF patients receiving adjusted-dose VKAs that reported INR control measures (TTR and PINRR) and/or reported an INR measurement coinciding with thromboembolic or hemorrhagic events. Random-effects meta-analyses and meta-regression were performed.
Ninety-five articles were included. Sixty-eight VKA-treated study groups reported measures of INR control, while 43 studies reported an INR around the time of the adverse event. Patients spent 61% (95% CI, 59–62%), 25% (95% CI, 23–27%) and 14% (95% CI, 13-15%) of their time within, below or above the therapeutic range. PINRR assessments were within, below, and above range 56% (95% CI, 53–59%), 26% (95% CI, 23–29%) and 13% (95% CI, 11-17%) of the time. Patients receiving VKA management in the community spent less TTR than those managed by anticoagulation clinics or in randomized trials. Patients newly receiving VKAs spent less TTR than those with prior VKA use. Patients in Europe/United Kingdom spent more TTR than patients in North America. Fifty-seven percent (95% CI, 50-64%) of thromboembolic events and 42% (95% CI, 35 – 51%) of hemorrhagic events occurred at an INR <2.0 and >3.0, respectively; while 56% (95% CI, 48-64%) of ischemic strokes and 45% of intracranial hemorrhages (95% CI, 29-63%) occurred at INRs <2.0 and >3.0, respectively.
Patients on VKAs for AF frequently have INRs outside the therapeutic range. While, thromboembolic and hemorrhagic events do occur patients with a therapeutic INR; patients with an INR <2.0 make up many of the cases of thromboembolism, while those >3.0 make up many of the cases of hemorrhage. Managing anticoagulation outside of a clinical trial or anticoagulation clinic is associated with poorer INR control, as is, the initiation of therapy in the VKA-naïve. Patients in Europe/UK have better INR control than those in North America.
PMCID: PMC4094926  PMID: 25024644
Vitamin K antagonists; Atrial fibrillation; International normalized ratio; Anticoagulation
12.  Telephone-based anticoagulation management in the homebound setting: a retrospective observational study 
Anticoagulation management is currently performed through anticoagulation clinics or self-managed with or without the help of medical services. Homebound patients are a unique population that cannot utilize anticoagulation clinics or self-testing. Telephone-based anticoagulation management could be an alternative to the traditional methods of monitoring warfarin in this subgroup. The objective of this retrospective, observational study is to investigate the feasibility of warfarin management in homebound patients.
This study was performed through the use of telephone-based adjustments of warfarin dose based on an international normalized ratio (INR) result. Four hundred forty-eight homebound patients referred to the anticoagulation clinic at Staten Island University Hospital were visited at home by a phlebotomist; a blood sample was drawn for initial laboratory testing. A nurse practitioner then called the patient or designated person to relay the INR result and to direct dosage adjustment. INR results and dosage changes were entered into an electronic medical record and analyzed statistically.
The mean percentage of INR values in range was 58.39%. The mean time when the INR was in the therapeutic range was 62.75%. The percent of patients who were therapeutically controlled decreased as the number of medications increased. The complication rate was 4% per patient year, with an equal distribution between bleeding and clotting. These values compared favorably to other studies in which monitoring was performed through anticoagulation clinics or self-monitoring. The cost per visit at our anticoagulation clinic was found to be approximately $300 compared with $82 when utilizing our homebound service.
Telephone-based management of warfarin therapy in the homebound setting is feasible. It can lower the cost of health care expenditures compared to other modalities of anticoagulation management.
PMCID: PMC3857151  PMID: 24348065
warfarin; anticoagulation; homebound; telephone-based; anticoagulation clinic; INR
13.  Implementation of Pharmacist-Managed Anticoagulation Clinic in a Saudi Arabian Health Center 
Hospital Pharmacy  2014;49(3):260-268.
During the past 2 decades, a paradigm shift in the management of oral anticoagulation therapy has occurred. A multidisciplinary approach has been used and has proved beneficial from both a cost and quality perspective. However, this approach to anticoagulation therapy is not well established in Saudi Arabia and the Middle East, and the traditional way of managing anticoagulation patients is still the mainstay of care. The Pharmacy Services Division (PSD) in collaboration with physician, nursing, and medical support enterprises at the Dhahran Health Center established the pharmacy-managed anticoagulation clinic (ACC).
To describe the implementation process of the first pharmacist-managed anticoagulation clinic in the eastern province of Saudi Arabia and its impact on patient care.
The PSD in collaboration with medical staff successfully created a care delivery model utilizing clinical pharmacists’ expertise to provide comprehensive anticoagulation management services at Saudi Aramco Medical Services Organization (SAMSO). Planning included analyzing existing practices, reviewing the relevant literature, obtaining physician input, formulating a business proposal, and developing clinical protocols and guidelines. Collaborative relationships were established with the center laboratory, scheduling services, and nursing and medical departments. Clinic services include patient assessment, anticoagulation monitoring, warfarin dosage adjustment, medication dispensing at the clinic, patient education, and feedback to referring physicians. Data (2 years before and after clinic inception) for all patients enrolled at the anticoagulation clinic were reviewed to evaluate the impact of the clinic on anticoagulation management, adverse events, and patient satisfaction.
A total of 578 patients were enrolled in the ACC. The total percentage of international normalized ratio (INR) within the target range was 59% versus 48% when compared to the previous traditional practice. The number of INR tests per patient dropped by 19%. Minor and major adverse events occurred in 10% and 1.5% of patients, respectively. Overall, the patients were very satisfied with the new clinic compared to the previous practice.
Implementation of the pharmacist-managed ACC in the eastern province of Saudi Arabia had a positive impact on patient care based on the improvements in the number of patients whose INR was within therapeutic range and patient satisfaction scores.
PMCID: PMC3971112  PMID: 24715746
ambulatory care; anticoagulation; INR; pharmacist-managed clinic; warfarin
14.  Is the international normalised ratio (INR) reliable? A trial of comparative measurements in hospital laboratory and primary care settings. 
Journal of Clinical Pathology  1999;52(7):494-497.
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.
PMCID: PMC501488  PMID: 10605400
15.  Comparison of warfarin therapy clinical outcomes following implementation of an automated mobile phone-based critical laboratory value text alert system 
BMC Medical Genomics  2014;7(Suppl 1):S13.
Computerized alert and reminder systems have been widely accepted and applied to various patient care settings, with increasing numbers of clinical laboratories communicating critical laboratory test values to professionals via either manual notification or automated alerting systems/computerized reminders. Warfarin, an oral anticoagulant, exhibits narrow therapeutic range between treatment response and adverse events. It requires close monitoring of prothrombin time (PT)/international normalized ratio (INR) to ensure patient safety. This study was aimed to evaluate clinical outcomes of patients on warfarin therapy following implementation of a Personal Handy-phone System-based (PHS) alert system capable of generating and delivering text messages to communicate critical PT/INR laboratory results to practitioners' mobile phones in a large tertiary teaching hospital.
A retrospective analysis was performed comparing patient clinical outcomes and physician prescribing behavior following conversion from a manual laboratory result alert system to an automated system. Clinical outcomes and practitioner responses to both alert systems were compared. Complications to warfarin therapy, warfarin utilization, and PT/INR results were evaluated for both systems, as well as clinician time to read alert messages, time to warfarin therapy modification, and monitoring frequency.
No significant differences were detected in major hemorrhage and thromboembolism, warfarin prescribing patterns, PT/INR results, warfarin therapy modification, or monitoring frequency following implementation of the PHS text alert system. In both study periods, approximately 80% of critical results led to warfarin discontinuation or dose reduction. Senior physicians' follow-up response time to critical results was significantly decreased in the PHS alert study period (46.3% responded within 1 day) compared to the manual notification study period (24.7%; P = 0.015). No difference in follow-up response time was detected for junior physicians.
Implementation of an automated PHS-based text alert system did not adversely impact clinical or safety outcomes of patients on warfarin therapy. Approximately 80% immediate recognition of text alerts was achieved. The potential benefits of an automated PHS alert for senior physicians were demonstrated.
PMCID: PMC4101312  PMID: 25079609
16.  Self-monitoring of oral anticoagulation: does it work outside trial conditions? 
Journal of Clinical Pathology  2009;62(2):168-171.
Patient self-monitoring (PSM) of oral anticoagulation therapy (OAT) can improve anticoagulant control, but poor uptake and high dropout rates have prompted suggestions that PSM is suitable for only a minority of patients in the UK.
To determine whether PSM could be a viable alternative to regular hospital anticoagulant clinic attendance, if offered from the start of treatment.
318 consecutive patients referred, for the first time, to an anticoagulation clinic were assessed for eligibility using established criteria. Patients electing for PSM attended training and, following successful assessment, performed a capillary blood INR every two weeks or more frequently if directed to do so by the anticoagulation clinic. Primary outcome measures were uptake of PSM and the percentage time in target therapeutic INR range (TIR) compared to patients electing for routine clinic care.
Of 318 patients referred for OAT, 188 were eligible for PSM. 84 (26%) elected to self-monitor, of whom 72 (23%) remained self-monitoring or had completed their course of treatment at the end of the audit. Self-monitoring patients had significantly better anticoagulant control than those receiving routine hospital anticoagulation clinic care (TIR 71% vs 60%, p = 0.003) and significantly less time outside critical limits, ie, INR <1.5 or >5.0 (0.45% vs 2.04%, p = 0.008).
Patients offered PSM from the start of treatment show increased uptake compared to previous UK studies and a level of oral anticoagulation control comparable to that reported in previous clinical trials.
PMCID: PMC2629005  PMID: 19181634
17.  Oral anticoagulation in a pediatric hospital: impact of a quality improvement initiative on warfarin management strategies 
Quality & Safety in Health Care  2006;15(4):240-243.
There are potential risks associated with the use of warfarin in children, particularly as the dosing requirements may decrease as patients get older.
Our facility is a 715‐bed freestanding pediatric tertiary care center with a large cardiac surgery center. A significant number of patients receive warfarin for treatment or prophylaxis of thromboembolic events while in hospital.
Key measures for improvement
Initial dose of warfarin and time taken to achieve goal therapeutic international normalized ratio (INR).
Strategies for change
The intervention included: (1) revision of hospital drug formulary so that warfarin dosing was in accordance with the most recent guidelines; (2) warfarin administration restricted to one time of the day (12.00 noon); (3) target therapeutic INR level documented with each warfarin order; and (4) pharmacy computer system mandated that the pharmacist confirmed the target INR, documented the most current INR, and compared the dose with the formulary guidelines. If the warfarin dose was not in accordance with the formulary guidelines, the pharmacist contacted the physician and made dosing recommendations according to the guidelines.
Effects of change
The number of patients with supratherapeutic INR values during the hospital admission was decreased by more than 50% and goal INR values were documented more frequently in the medical record. There was also an increase in subtherapeutic INR values. The intervention had no effect on the time taken to achieve the goal therapeutic INR.
Lessons learned
Instituting changes in a number of aspects of anticoagulation management and incorporating an intensive educational effort across a breadth of healthcare providers can improve anticoagulation management with warfarin in challenging patient populations such as children. Similar methods could possibly improve anticoagulation with other agents such as unfractionated heparin or low molecular weight heparin.
PMCID: PMC2564007  PMID: 16885247
warfarin; children; quality improvement; anticoagulation
18.  Factors determining patients’ intentions to use point-of-care testing medical devices for self-monitoring: the case of international normalized ratio self-testing 
To identify factors that determine patients’ intentions to use point-of-care medical devices, ie, portable coagulometer devices for self-testing of the international normalized ratio (INR) required for ongoing monitoring of blood-coagulation intensity among patients on long-term oral anticoagulation therapy with vitamin K antagonists, eg, warfarin.
A cross-sectional study that applied the technology-acceptance model through a self-completed questionnaire, which was administered to a convenience sample of 125 outpatients attending outpatient anticoagulation services at a district general hospital in London, UK. Data were analyzed using descriptive statistics, factor analyses, and structural equation modeling.
The participants were mainly male (64%) and aged ≥ 71 years (60%). All these patients were attending the hospital outpatient anticoagulation clinic for INR testing; only two patients were currently using INR self-testing, 84% of patients had no knowledge about INR self-testing using a portable coagulometer device, and 96% of patients were never offered the option of the INR self-testing. A significant structural equation model explaining 79% of the variance in patients’ intentions to use INR self-testing was observed. The significant predictors that directly affected patients’ intention to use INR self-testing were the perception of technology (β = 0.92, P < 0.001), trust in doctor (β = −0.24, P = 0.028), and affordability (β = 0.15, P = 0.016). In addition, the perception of technology was significantly affected by trust in doctor (β = 0.43, P = 0.002), age (β = −0.32, P < 0.001), and affordability (β = 0.23, P = 0.013); thereby, the intention to use INR self-testing was indirectly affected by trust in doctor (β = 0.40), age (β = −0.29), and affordability (β = 0.21) via the perception of technology.
Patients’ intentions to use portable coagulometers for INR self-testing are affected by patients’ perceptions about the INR testing device, the cost of device, trust in doctors/clinicians, and the age of the patient, which need to be considered prior to any intervention involving INR self-testing by patients. Manufacturers should focus on increasing the affordability of INR testing devices for patients’ self-testing and on the potential role of medical practitioners in supporting use of these medical devices as patients move from hospital to home testing.
PMCID: PMC3536357  PMID: 23300344
oral anticoagulation; INR self-testing; technology-acceptance model; trust in doctor; home testing; affordability; structural equation modeling
19.  Differences in the INR evaluation of two different thromboplastins in patients with positivity to lupus anticoagulant in ongoing oral anticoagulation 
A possible interference between lupus anticoagulant (LAC), a well characterized clotting inhibitor, in the International Normalized Ratio (INR) determination during oral anticoagulation (OA) has been reported in the literature. Few data are available about the relationship between this kind of interference and the daily clinical management of oral anticoagulation. The aim of the study is to evaluate the role of two different thromboplastins–RecombiPlasTin 2G and HepatoComplex–in the determination of INR values of several patients’ ongoing OA for a previous thrombotic disorder with and without positivity to LAC, and to evaluate possible interferences in the daily therapeutic approach.
Patients and methods:
We selected 16 patients (13 females and 3 males, mean age 59 ± 16 years) with LAC positivity ongoing OA and 11 control subjects (7 females and 4 males, mean age 58 ± 14.5 years) with similar characteristics (ie, ethnic background and weight) with LAC negativity ongoing OA. 165 assays for INR determination were analyzed from both groups. Statistical analysis was performed using STATA 10 software. P values were considered significant if <0.05.
Mean values of INR for patients with LAC positivity were 3.79 ± 1.63 when tested with RecombiPlasTin 2G vs 3.18 ± 1.15 when tested with HepatoComplex (P < 0.001, s); while mean values of INR for patients with antiphospholipid syndrome (APS) with LAC negativity were 3.54 ± 1.39 when tested with RecombiPlasTin 2G vs 3.23 ± 1.14 when tested with HepatoComplex (P < 0.002, s). An INR value > than 4.5 was found in 31/165 samples in 9 subjects, 8 patients with LAC positivity, and 1 control group subject with LAC negativity. There was a great difference in INR values in these subjects if we use the common thromboplastin (ie, RecombiPlasTin 2G) with a INR range varying from 5.14 ± 0.35 vs 3.79 ± 0.38 if we use another thromboplastin (ie, HepatoComplex) (P < 0.001, s). A change in the therapeutic approach for OA is possible in these cases because different INR values were obtained using different thromboplastins.
Our data confirm that INR evaluation does not reveal significant changes also if tested with two different thromboplastins, for patients ongoing OA with and without LAC positivity, when the INR value is < than 4. Over this INR value there is a significant difference in patients with LAC positivity if we use a different thromboplastin for the INR determination. For this reason values obtained by RecombiPlasTin 2G need to be confirmed and matched with another thromboplastin (ie, HepatoComplex). This approach may be useful in order to have a good INR testing for the chronic long-term treatment with OA in particular in patients with LAC positivity.
PMCID: PMC3262322  PMID: 22282684
lupus anticoagulant; oral anticoagulation; INR; thromboplastin; prothrombin time; thrombosis; long-term treatment
20.  The Clinical and Economic Impact of Point-of-Care CD4 Testing in Mozambique and Other Resource-Limited Settings: A Cost-Effectiveness Analysis 
PLoS Medicine  2014;11(9):e1001725.
Emily Hyle and colleagues conduct a cost-effectiveness analysis to estimate the clinical and economic impact of point-of-care CD4 testing compared to laboratory-based tests in Mozambique.
Please see later in the article for the Editors' Summary
Point-of-care CD4 tests at HIV diagnosis could improve linkage to care in resource-limited settings. Our objective is to evaluate the clinical and economic impact of point-of-care CD4 tests compared to laboratory-based tests in Mozambique.
Methods and Findings
We use a validated model of HIV testing, linkage, and treatment (CEPAC-International) to examine two strategies of immunological staging in Mozambique: (1) laboratory-based CD4 testing (LAB-CD4) and (2) point-of-care CD4 testing (POC-CD4). Model outcomes include 5-y survival, life expectancy, lifetime costs, and incremental cost-effectiveness ratios (ICERs). Input parameters include linkage to care (LAB-CD4, 34%; POC-CD4, 61%), probability of correctly detecting antiretroviral therapy (ART) eligibility (sensitivity: LAB-CD4, 100%; POC-CD4, 90%) or ART ineligibility (specificity: LAB-CD4, 100%; POC-CD4, 85%), and test cost (LAB-CD4, US$10; POC-CD4, US$24). In sensitivity analyses, we vary POC-CD4-specific parameters, as well as cohort and setting parameters to reflect a range of scenarios in sub-Saharan Africa. We consider ICERs less than three times the per capita gross domestic product in Mozambique (US$570) to be cost-effective, and ICERs less than one times the per capita gross domestic product in Mozambique to be very cost-effective. Projected 5-y survival in HIV-infected persons with LAB-CD4 is 60.9% (95% CI, 60.9%–61.0%), increasing to 65.0% (95% CI, 64.9%–65.1%) with POC-CD4. Discounted life expectancy and per person lifetime costs with LAB-CD4 are 9.6 y (95% CI, 9.6–9.6 y) and US$2,440 (95% CI, US$2,440–US$2,450) and increase with POC-CD4 to 10.3 y (95% CI, 10.3–10.3 y) and US$2,800 (95% CI, US$2,790–US$2,800); the ICER of POC-CD4 compared to LAB-CD4 is US$500/year of life saved (YLS) (95% CI, US$480–US$520/YLS). POC-CD4 improves clinical outcomes and remains near the very cost-effective threshold in sensitivity analyses, even if point-of-care CD4 tests have lower sensitivity/specificity and higher cost than published values. In other resource-limited settings with fewer opportunities to access care, POC-CD4 has a greater impact on clinical outcomes and remains cost-effective compared to LAB-CD4. Limitations of the analysis include the uncertainty around input parameters, which is examined in sensitivity analyses. The potential added benefits due to decreased transmission are excluded; their inclusion would likely further increase the value of POC-CD4 compared to LAB-CD4.
POC-CD4 at the time of HIV diagnosis could improve survival and be cost-effective compared to LAB-CD4 in Mozambique, if it improves linkage to care. POC-CD4 could have the greatest impact on mortality in settings where resources for HIV testing and linkage are most limited.
Please see later in the article for the Editors' Summary
Editors' Summary
AIDS has already killed about 36 million people, and a similar number of people (mostly living in low- and middle-income countries) are currently infected with HIV, the virus that causes AIDS. HIV destroys immune system cells (including CD4 cells, a type of lymphocyte), leaving infected individuals susceptible to other infections. Early in the AIDS epidemic, HIV-infected individuals usually died within ten years of infection. After effective antiretroviral therapy (ART) became available in 1996, HIV infection became a chronic condition for people living in high-income countries, but because ART was expensive, HIV/AIDS remained a fatal disease in low- and middle-income countries. In 2003, the international community began to work towards achieving universal ART coverage, and by the end of 2012, 61% of HIV-positive people (nearly 10 million individuals) living low- and middle-income countries who were eligible for treatment—because their CD4 cell count had fallen below 350 cells/mm3 of blood or they had developed an AIDS-defining condition—were receiving treatment.
Why Was This Study Done?
In sub-Saharan Africa nearly 50% of HIV-infected people eligible for treatment remain untreated, in part because of poor linkage between HIV diagnosis and clinical care. After patients receive a diagnosis of HIV infection, their eligibility for ART initiation is determined by sending a blood sample away to a laboratory for a CD4 cell count (the current threshold for treatment is a CD4 count below 500/mm3, although low- and middle-income countries have yet to update their national guidelines from the threshold CD4 count below 350/mm3). Patients have to return to the clinic to receive their test results and to initiate ART if they are eligible for treatment. Unfortunately, many patients are “lost” during this multistep process in resource-limited settings. Point-of-care CD4 tests at HIV diagnosis—tests that are done on the spot and provide results the same day—might help to improve linkage to care in such settings. Here, the researchers use a mathematical model to assess the clinical outcomes and cost-effectiveness of point-of-care CD4 testing at the time of HIV diagnosis compared to laboratory-based testing in Mozambique, where about 1.5 million HIV-positive individuals live.
What Did the Researchers Do and Find?
The researchers used a validated model of HIV testing, linkage, and treatment called the Cost-Effectiveness of Preventing AIDS Complications–International (CEPAC-I) model to compare the clinical impact, costs, and cost-effectiveness of point-of-care and laboratory CD4 testing in newly diagnosed HIV-infected patients in Mozambique. They used published data to estimate realistic values for various model input parameters, including the probability of linkage to care following the use of each test, the accuracy of the tests, and the cost of each test. At a CD4 threshold for treatment of 250/mm3, the model predicted that 60.9% of newly diagnosed HIV-infected people would survive five years if their immunological status was assessed using the laboratory-based CD4 test, whereas 65% would survive five years if the point-of-care test was used. Predicted life expectancies were 9.6 and 10.3 years with the laboratory-based and point-of-care tests, respectively, and the per person lifetime costs (which mainly reflect treatment costs) associated with the two tests were US$2,440 and $US2,800, respectively. Finally, the incremental cost-effectiveness ratio—calculated as the incremental costs of one therapeutic intervention compared to another divided by the incremental benefits—was US$500 per year of life saved, when comparing use of the point-of-care test with a laboratory-based test.
What Do These Findings Mean?
These findings suggest that, compared to laboratory-based CD4 testing, point-of-care testing at HIV diagnosis could improve survival for HIV-infected individuals in Mozambique. Because the per capita gross domestic product in Mozambique is US$570, these findings also indicate that point-of-care testing would be very cost-effective compared to laboratory-based testing (an incremental cost-effectiveness ratio less than one times the per capita gross domestic product is regarded as very cost-effective). As with all modeling studies, the accuracy of these findings depends on the assumptions built into the model and on the accuracy of the input parameters. However, the point-of-care strategy averted deaths and was estimated to be cost-effective compared to the laboratory-based test over a wide range of input parameter values reflecting Mozambique and several other resource-limited settings that the researchers modeled. Importantly, these “sensitivity analyses” suggest that point-of-care CD4 testing is likely to have the greatest impact on HIV-related deaths and be economically efficient in settings in sub-Saharan Africa with the most limited health care resources, provided point-of-care CD4 testing improves the linkage to care for HIV-infected people.
Additional Information
Please access these websites via the online version of this summary at
The World Health Organization provides information on all aspects of HIV/AIDS (in several languages); its “Consolidated Guidelines on the Use of Antiretroviral Drugs for Treating and Preventing HIV Infections: Recommendations for a Public Health Approach”, which highlights the potential of point-of-care tests to improve the linkage of newly diagnosed HIV-infected patients to care, is available
Information is available from the US National Institute of Allergy and Infectious Diseases on HIV infection and AIDS
NAM/aidsmap provides basic information about HIV/AIDS, and summaries of recent research findings on HIV care and treatment; it has a fact sheet on CD4 testing
Information is available from Avert, an international AIDS charity, on many aspects of HIV/AIDS, including information on starting, monitoring, and switching treatment and on HIV and AIDS in sub-Saharan Africa (in English and Spanish)
The “UNAIDS Report on the Global AIDS Epidemic 2013” provides up-to-date information about the AIDS epidemic and efforts to halt it
Personal stories about living with HIV/AIDS are available through Avert, Nam/aidsmap, and Healthtalkonline
PMCID: PMC4165752  PMID: 25225800
21.  A sensitivity comparison of the Quick and Owren prothrombin time methods in oral anticoagulant therapy 
Hematology Reviews  2009;1(2):e15.
Prothrombin time (PT) is the leading test for monitoring oral anticoagulation therapy (OAT). According to the World Health Organization recommendation, International Normalized Ratio (INR) results obtained from the same patient samples with the major PT methods (Quick and Owren) should be the same when the therapeutic range is the same. In our study blood samples were obtained from 207 OAT patients. We analyzed the samples using two Quick and two Owren PT (combined thromboplastin) reagents for INR and assessed the sensitivity and true coagulation activity using a new-generation PT method. The INR values with the Quick PT and Owren PT methods were very similar around the normal range, while unacceptable differences were seen within the therapeutic range and at higher INR values. The Quick PT results as INR are clearly lower than those given by Owren PT and the difference increases toward higher INR. The new PT method functions well with both Owren PT reagents, and we can calculate the true active INR. The Quick PT methods show no sensitivity to coagulation inhibition measurement. The harmonization of the INR is an important goal for the safety of OAT patients. More accurate INR results reduce morbidity and mortality, and the therapeutic ranges should be similar worldwide. In this study we found unacceptable differences in INR results produced by the two PT methods. The new method showed a lack of sensitivity to Quick PT. For the global harmonization of OAT therapy and for INR accuracy only the more sensitive Owren PT method should be used.
PMCID: PMC3222250
International Normalized Ratio; oral anticoagulant therapy; prothrombin time; warfarin.
22.  Effective and Safe Management of Oral Anticoagulation Therapy in Patients Who Use the Internet-Accessed Telecontrol Tool SintromacWeb 
Despite the existing evidence that highlights the benefits of oral anticoagulation therapy (OAT) self-testing and self-management by patients in comparison with conventional control, significant progress is still needed in the implementation of computer-based, Internet-assisted systems for OAT within health care centers. The telecontrol tool “SintromacWeb” is a previously validated system for OAT management at home, which is currently operative and accessed by patients through a hospital Web portal.
The intent of the study was to assess the effectiveness and safety of OAT management in patients using the SintromacWeb telecontrol system in reference to control in patients using the conventional system (management at the hematology department), in terms of time in therapeutic range (TTR) of International Normalized Ratio (INR).
In this observational prospective study, patients were identified by their physician and divided in two groups according to the OAT management system that they were already using (conventional control or telecontrol with SintromacWeb). For 6 months, patients were required to visit the hematology department every time their physician considered it necessary according to usual clinical practice. Sociodemographic and clinical variables for the study were collected at first visit (baseline) and at those visits closest to 2, 4, and 6 months after first visit.
A total of 173 patients were evaluated, 87 with conventional control and 86 with telecontrol. Follow-up time was a median of 6.3 (range 5.2-8.1) months. The average time of OAT treatment prior to enrollment was 9.2 (SD 6.4) years. Patients in the telecontrol group tested their INR a median of 21 (range 4-22) days versus a median of 35 (range 14-45) days in patients in the conventional control group (P<.001). TTR in the telecontrol group was 107 (SD 37) days versus 94 (SD 37) days in the conventional control group (an increase of 12.6%; P=.02). In all visits, the percentage of TTR was higher in the telecontrol group (at the third visit: 59% vs 48%; P=.01). Higher TTR (positive coefficient) was associated with patients under OAT telecontrol (P=.03). Under-anticoagulation (INR<1.5) and over-anticoagulation (INR>5) were observed in 34 (19.7%, 34/173) and 38 (22.0%, 38/173) patients, respectively (no differences between treatment groups). Seven thrombotic and/or bleeding events were serious, 12 were non-serious, and most of them (5 and 10, respectively) occurred in the conventional control group.
In clinical practice, OAT management with the Internet-based tool SintromacWeb is effective and safe for those patients who are eligible for OAT telecontrol.
PMCID: PMC4420842  PMID: 25900775
oral anticoagulant therapy; International Normalized Ratio; Internet; self-management software; telecontrol; SintromacWeb
23.  A primary care evaluation of three near patient coagulometers. 
Journal of Clinical Pathology  1999;52(11):842-845.
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.
PMCID: PMC501598  PMID: 10690176
24.  How Well Does the Target INR Level Maintain in Warfarin-Treated Patients with Non-ValvularAtrial Fibrillation? 
Yonsei Medical Journal  2009;50(1):83-88.
Although warfarin is an effective oral anticoagulation (OAC) drug to reduce the risk of thromboembolism in patients with non-valvular atrial fibrillation (NVAF), long term follow-up data are scarce to be certain whether the target INR level is maintained in warfarin-treated patients in Korea. The aim of this study was to evaluate how well INRs are maintained within the target range using a new index, INR stability (= 100 × number of INRs within target range/total number of INR measurements) which we made, and to find out any correlation between thromboembolic events and INR stability.
Materials and Methods
This study was an observational analysis of retrospectively collected data of 129 patients with NVAF from April 2000 to December 2005 at a single tertiary hospital. All patients were registered at the anticoagulation service.
The median duration of follow up was 2.03 years (interquartile range 1.35 - 2.96). During the follow-up period, 60.9 ± 14.9% of the INR were within the target INR range. INR stability was not significantly different between patients without and with stroke (61.2 ± 15.0% vs 53.3 ± 4.9%). Among the known factors affecting fluctuations of the INR value, the most frequent factor was noncompliance (41.8%).
The present study showed that it was not enough to maintain INR values within the target range in warfarin-treated patients with NVAF even at a tertiary hospital. Noncompliance is an important problem which interferes with maintaining target INR range.
PMCID: PMC2649856  PMID: 19259353
Anticoagulation; atrial fibrillation
25.  Demonstration of anticoagulation patient self-testing feasibility at an Indian Health Service facility: A case series analysis 
Pharmacy Practice  2013;11(1):30-37.
Anticoagulation patient self-testing (PST) represents an alternative approach to warfarin monitoring by enabling patients to use coagulometers to test their international normalized ratio (INR) values. PST offers several advantages that potentially improve warfarin management.
To describe implementation and associated performance of a PST demonstration program at an Indian Health Service (IHS) facility.
A non-consecutive case series analysis of patients from a pharmacy-managed PST demonstration program was performed at an IHS facility in Oklahoma between July 2008 and February 2009.
Mean time in therapeutic range (TTR) for the seven patients showed a small, absolute increase during the twelve weeks of PST compared to the twelve weeks prior to PST. Four of the seven patients had an increase in TTR during the twelve week course of PST compared to their baseline TTR. Three of four patients with increased TTR in the final eight week period of PST achieved a TTR of 100%. Of the three patients who experienced a decrease in TTR after initiating self-testing, two initially presented with a TTR of 100% prior to PST and one patient had a TTR of 100% for the final eight weeks of PST. The two patients not achieving a TTR of 100% during the twelve week PST period demonstrated an increase in TTR following the first four weeks of PST.
Although anticoagulation guidelines now emphasize patient self-management (PSM) only, optimal PST remains an integral process in PSM delivery. In the patients studied, the results of this analysis suggest that PST at the IHS facility provided a convenient, alternative method for management of chronic warfarin therapy for qualified patients. More than half of the patients demonstrated improvement in TTR. Although there is a learning curve immediately following PST initiation, the mean TTR for the entire PST period increased modestly when compared to the time period prior to PST.
PMCID: PMC3780503  PMID: 24155847
Self Care; Anticoagulants; Warfarin; International Normalized Ratio; Drug Monitoring; United States

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