International Normalized Ratio Results Research Articles

Assessing Clinical Laboratory Quality: A College of American Pathologists Q-Probes Study of Prothrombin Time INR Structures, Processes, and Outcomes in 98 Laboratories.

The anticoagulant warfarin has been identified as the second most frequent drug responsible for serious, disabling, and fatal adverse drug events in the United States, and its effect on blood coagulation is monitored by the laboratory test called international normalized ratio (INR). To determine the presence of INR policies and procedures, INR practices, and completeness and timeliness of reporting critical INR results in participants' clinical laboratories. Participants reviewed their INR policies and procedure requirements, identified their practices by using a questionnaire, and studied completeness of documentation and timeliness of reporting critical value INR results for outpatients and emergency department patients. In 98 participating institutions, the 5 required policies and procedures were in place in 93% to 99% of clinical laboratories. Fifteen options for the allowable variations among duplicate results from different analyzers, 12 different timeliness goals for reporting critical values, and 18 unique critical value limits were used by participants. All required documentation elements were present in 94.8% of 192 reviewed INR validation reports. Critical value INR results were reported within the time frame established by the laboratory for 93.4% of 2604 results, but 1.0% of results were not reported. Although the median laboratories successfully communicated all critical results within their established time frames and had all the required validation elements based in their 2 most recent INR calculations, those participants at the lowest 10th percentile were successful in 80.0% and 85.7% of these requirements, respectively. Significant opportunities exist for adherence to INR procedural requirements and for practice patterns and timeliness goals for INR critical results' reporting.

Point of care coagulometry in prehospital emergency care: an observational study.

BackgroundHaemostatic impairment can have a crucial impact on the outcome of emergency patients, especially in cases of concomitant antithrombotic drug treatment. In this prospective observational study we used a point of care (POC) coagulometer in a prehospital physician-based emergency medical system in order to test its validity and potential value in the treatment of emergency patients.MethodsDuring a study period of 12 months, patients could be included if venous access was mandatory for further treatment. The POC device CoaguChek® was used to assess international normalized ratio (INR) after ambulance arrival at the scene. Results were compared with in-hospital central laboratory assessment of INR. The gain of time was analysed as well as the potential value of POC testing through a questionnaire completed by the responsible prehospital emergency physician.ResultsA total of 103 patients were included in this study. POC INR results were highly correlated with results of conventional assessment of INR (Bland-Altman-bias: 0.014). Using a cutoff value of INR >1.3, the device’s sensitivity to detect coagulopathy was 100 % with a specificity of 98.7 %. The median gain of time was 69 min. Treating emergency physicians considered the value of prehospital POC INR testing ‘high’ in 9 % and ‘medium’ in 21 % of all patients. In patients with tracer diagnosis ‘neurology’, the value of prehospital INR assessment was considered ‘high’ or ‘medium’ (63 %) significantly more often than in patients with non-neurological tracer diagnoses (24 %).ConclusionsAssessment of INR through a POC coagulometer is feasible in prehospital emergency care and provides valuable information on haemostatic parameters in patients. Questionnaire results suggest that POC INR testing may present a valuable technique in selected patients. Whether this information translates into an improved management of respective patients has to be evaluated in further studies.

Patient Specific Factors Influencing Adherence to INR Monitoring.

The specific reasons underlying nonadherence to monitoring the international normalized ratio (INR) from the patient's perspective have not been formally studied. Understanding why patients do or do not adhere has the potential to reveal useful targets for improving adherence to INR monitoring or alternative treatment strategies. The objective of this study was to gain further insight into INR monitoring nonadherence from the patient's perspective. This qualitative study was conducted among members of Kaiser Permanente Colorado; patients were characterized as adherent or nonadherent and recruited from the Clinical Pharmacy Anticoagulation and Anemia Service to participate in an individual interview. Qualitative analysis was performed to identify emerging themes using an inductive approach. Demographic data were summarized using descriptive statistics. Patients were primarily white and employed with a mean age of 61.3years. Perspectives and experiences were similar for all interviewed patients regardless of classification as adherent or nonadherent. The most common themes were the desire for INR monitoring to be inexpensive, convenient, and accessible; finding reassurance with INR monitoring; and a preference for interacting with the same group of prescribers, pharmacists, and phlebotomists. The following strategies to improve adherence to INR testing are suggested: (i) assign anticoagulation providers to work with the same patients consistently; (ii) provide formal INR reminders; (iii) avoid harsh language or lecturing patients following missed INR tests; (iv) reinforce the clinical and psychological utility of INR results; and (v) facilitate access to INR testing. Adopting these strategies into clinical practice can support the patient-clinician relationship and empower patients to be more engaged in their health care.

Warfarin and Rivaroxaban Duplication: A Case Report and Medication Error Analysis.

A 62-year-old African American man received unintentional duplicate anticoagulation therapy with warfarin 5 mg and rivaroxaban 20 mg daily for the treatment of recurrent pulmonary embolism. The patient presented to the anticoagulation clinic 6 days after hospital discharge with an International Normalized Ratio (INR) of 2.3 and he was instructed to continue warfarin 5 mg daily. Seven days later, he returned to the clinic with an INR >8.0 using a point-of-care device. He denied any signs or symptoms of bleeding. During the interview, he reported starting a new medication for neuropathy 5 days earlier. The clinical pharmacist contacted the dispensing pharmacy and determined rivaroxaban 20 mg was the new medication. The patient denied receiving new prescription counseling at the dispensing pharmacy. Because rivaroxaban can falsely elevate INR results, the actual INR value was unknown. To minimize the risk for recurrent venous thromboembolism, vitamin K was not administered and no warfarin doses were held. Rather, the patient was instructed to stop rivaroxaban and reduce the warfarin dose. Five days later, the patient returned with an INR of 4.3. He still had not experienced any signs or symptoms of bleeding. The patient was quickly stabilized on a warfarin maintenance dose of 22.5 mg weekly. The anticoagulation clinic pharmacist notified management at the clinic and at the dispensing pharmacy in an effort to identify process errors and prevent additional incidents.

Effect of distance to health facility on the maintenance of INR therapeutic ranges in rheumatic heart disease patients from Cape Town: no evidence for an association

BackgroundLack of adherence to international normalised ratio (INR) monitoring in rheumatic heart disease (RHD) patients is a contributor to cardio-embolic complications. This population-based observational study investigated whether the distance between home and an INR clinic affects the maintenance of therapeutic INR in RHD patients on warfarin.MethodsResidential addresses, INR clinics, and INR results of patients with RHD were extracted from the Cape Town component of the Global Rheumatic Heart Disease Registry (REMEDY) database. Addresses of homes and INR clinics were converted to geographical coordinates and verified in ArcGIS 10®. ArcGIS 10® and Google Maps® were used for spatial mapping and obtaining shortest road distances respectively. The travel distance between the home and INR clinic was correlated with time within therapeutic range (TTR) using the Rosendaal linear interpolation method, and with the fraction of INR within range, based on an average of three INR readings of patients and compared with recommended therapeutic ranges.ResultsRHD patients (n = 133) resided between 0.2 km and 50.8 km (median distance, 3.60 km) from one of 33 INR clinics. There was no significant difference in the achievement of the therapeutic INR between patients who travelled a shorter distance compared to those who travelled a longer distance (in range = 3.50 km versus out of range = 3.75 km, p = 0.78). This finding was the same for patients with mechanical valve replacement (n = 105) (3.50 km versus 3.90 km, p = 0.81), and native valves (3.45 km versus 2.75 km, p = 0.84).ConclusionsThere is no association between the maintenance of INR within therapeutic range amongst RHD patients in Cape Town and distance from patients’ residence to the INR clinic.

Reliability of a point-of-care device for international normalized ratio testing during the three surgical phases of orthotopic liver transplantation: a retrospective observational study.

To investigate the reliability of a point-of-care device, the HEMOCHRON(®) Jr. Signature, for measuring the international normalized ratio (INR) during the three surgical phases of liver transplantation. A retrospective review was performed on patients undergoing liver transplantation during July to December 2013. Thirty-one patients who had simultaneous laboratory and point-of-care INR readings from each phase of liver transplant surgery (paleohepatic, anhepatic, and neohepatic) were eligible for inclusion. Bland-Altman analysis, Spearman's rank correlation, and four quadrant plots were used to compare INR results from the point-of-care device (pocINR) with those from the laboratory (labINR). Based on the Bland-Altman analysis, mean biases (95% prediction interval) were 0.10 (0.03 to 0.17), 0.19 (0.12 to 0.27), and 0.21 (0.01 to 0.43) for the paleohepatic, anhepatic, and neohepatic phases, respectively. The pocINR device showed a systematic underestimation of the labINR. The Spearman's rank correlation coefficients (95% confidence interval [CI]) were: Ρ=0.90 (95% CI 0.80 to 0.95); Ρ=0.92 (95% CI 0.71 to 0.93); and Ρ=0.71 (95% CI 0.46 to 0.85), respectively. Direction-of-change analysis between the paleohepatic to anhepatic and the anhepatic to neohepatic phases showed strong concordance of 84% and, also considering the small bias between the measurements, supports the use of the pocINR device in the clinical management of liver transplant surgery. Point-of-care INR was accurate prior to hepatic reperfusion, but reliability decreased in the neohepatic phase.

Security and cost comparison of INR self-testing and conventional hospital INR testing in patients with mechanical heart valve replacement.

BackgroundInternational normalized ratio (INR) self-testing can improve the management of anticoagulation therapy with warfarin for the patients following mechanical heart valve replacement. Several reviews and studies have demonstrated self-management as an option to improve patient’s outcome considerably after mechanical heart valve replacement. We sought to analyze the security, economy and discuss the prospect of self-testing of anticoagulation therapy in patients following mechanical heart valve replacement in China, and evaluate the accuracy and stability of CoaguChek XS portable INR-testing device.MethodsThis was a prospective self-controlled clinical study conducted with 526 patients receiving oral warfarin anticoagulation therapy after mechanical heart valve replacement in the period of Mar.1, 2012 – Nov.1, 2012 in Cardiovascular Surgery Department of West China Hospital of Sichuan University. The same patient performed INR testing with CoaguChek XS portable coagulometer (group1) and central lab (group 2) in parallel. The follow-up time was 6 months. Meanwhile, a questionnaire was handed out to survey the expenses required for the re-examination visits to the hospital, time, and anticoagulation complications.ResultsNo severe anticoagulation complications occurred in all the patients. No significant difference of the INR results were observed between group 1 and group 2, they showed significant relevance, r = 0.953(p < 0.05). Compared with the conventional method of INR testing in hospital, the portable coagulometer is convenient, quick and less traumatic. Self-testing of anticoagulation therapy reduced the cost and the time required for re-examination.ConclusionsResults of CoaguChek XS monitor are precise and have a good consistency and stability as compared with traditional laboratory testing. For the patients receiving anticoagulation therapy after mechanical heart valve replacement, the self-testing of anticoagulation therapy with portable coagulometer is a safe choice, and it has a promising future application in China.

Do Herbal Formulas Influence the International Normalized Ratio of Patients Taking Warfarin? A Retrospective Study

Warfarin is a common anticoagulant agent for cardiovascular diseases, and it is known to interact with several foods and drugs. Several studies report an interaction between warfarin and herbal medicines; however, the influence of herbal medicines on the international normalized ratio (INR) is still controversial. We investigated the influence of herbal formulas on INR of patients taking warfarin. We searched electronic medical records of inpatients for INR results. Then, we compared the changes in INR and any adverse events between the group taking herbal formulas and warfarin (herbal group) and another group taking warfarin only (nonherbal group). Eighty-six patients were included; 45 patients were assigned to the herbal group and 41 patients to the nonherbal group. The herbal group had taken the same dose of warfarin for a longer period. The nonherbal group had a slightly higher mean INR value than the herbal group. The ratio of INR less than 2 and greater than 3, the ratio of INR that increased or decreased by one or more compared to the initial INR, and the ratio of adverse events were not significantly different between the two groups. It is suggested that use of herbal formulas may not influence INR value.

CP-092 Clinical audit of prescriptions of prothrombin complex concentrate in a small hospital

BackgroundOur hospital has 100 beds available for short-term stays and 200 available for long-term stays. There is a contract between the hospital and the Regional Health Agency which requires a...

National Assessment of Warfarin Anticoagulation Therapy for Stroke Prevention in Atrial Fibrillation

Anticoagulation control with warfarin, as assessed by the international normalized ratio (INR), is challenging. Time in the therapeutic range has been inversely correlated with major hemorrhage, thrombosis, and mortality. Quest Diagnostics offers standardized INR laboratory testing services to approximately half of US physician practices. To inform national stroke prevention strategies, we evaluated anticoagulation control in office-based community practices. We selected individuals with ≥2 months of INR data, INR results of >1.2, and an ICD-9 diagnosis code of atrial fibrillation. Frequency of INR testing and time in the therapeutic range were analyzed by age, sex, length of testing period, number of referred patients per provider, and median household income (based on home ZIP code). We identified 138 319 individuals referred by 37 939 physicians, yielding a total of 2 683 674 INR results. Patients had a mean age of 74 years; 81% were ≥65 years of age, and 55% were ≥75 years of age. The mean time in the therapeutic range was 53.7% overall and improved with time on treatment, increasing from 47.6% for patients with <6 months of testing to 57.5% for those with ≥6 months of testing (P<0.0001). The number of patients tested per physician practice was positively associated with time in the therapeutic range. Younger age, female sex, and lower income were also independently associated with poorer anticoagulant control. This study demonstrates widespread suboptimal anticoagulation control, suggesting an urgent need to improve oral anticoagulation care for most patient segments in the United States.

Incidence of very high international normalised ratio (INR) and factors contributing to discrepant results

Background Healthscope Pathology offers a warfarin dosing service in Victoria and Queensland with a large number of patients. Very high INR results will inevitably occur and we routinely recommend hospital presentation for patients with INR > 9. Discrepant results compared to the subsequent hospital INR test are sometimes seen. Aims To identify the incidence of INR > 9 in Healthscope Pathology across Victoria and Queensland, the factors contributing to discrepant results, the incidence of bleeding in patients with INR>9 and the incidence of repeat INRs before therapeutic intervention. Methods Retrospective follow-up phone calls to patients and health care providers for all episodes of INR>9 from 01/07/ 2013 to 09/10/2013. Results INR>9 was detected in 130 episodes out of 100,321 INRs done (0.13%). Among 130 episodes, there was a discrepant result in 10 cases, a difficult venepuncture was documented in three cases, five cases were collected in paediatric tubes implying a difficult venepuncture, transfer of underfilled adult citrate tube to paediatric tube occurred in one case and the reason was unknown in one case. Fourteen out of 130 had a bleeding episode. In 41 episodes, vitamin K was given without rechecking INR first, among them only two were actively bleeding. Discussion In a busy dosing service, our rates of very high INR are very low. Even in very high INR, bleeding complications were uncommon. Problems at the point of collection are the major cause for discrepant INR results. Education of phlebotomists, doctors and nurses about the importance of proper collection technique will improve quality of INR result. Repeating INR is also crucial before instituting therapeutic measures. Healthscope Pathology offers a warfarin dosing service in Victoria and Queensland with a large number of patients. Very high INR results will inevitably occur and we routinely recommend hospital presentation for patients with INR > 9. Discrepant results compared to the subsequent hospital INR test are sometimes seen. To identify the incidence of INR > 9 in Healthscope Pathology across Victoria and Queensland, the factors contributing to discrepant results, the incidence of bleeding in patients with INR>9 and the incidence of repeat INRs before therapeutic intervention. Retrospective follow-up phone calls to patients and health care providers for all episodes of INR>9 from 01/07/ 2013 to 09/10/2013. INR>9 was detected in 130 episodes out of 100,321 INRs done (0.13%). Among 130 episodes, there was a discrepant result in 10 cases, a difficult venepuncture was documented in three cases, five cases were collected in paediatric tubes implying a difficult venepuncture, transfer of underfilled adult citrate tube to paediatric tube occurred in one case and the reason was unknown in one case. Fourteen out of 130 had a bleeding episode. In 41 episodes, vitamin K was given without rechecking INR first, among them only two were actively bleeding. In a busy dosing service, our rates of very high INR are very low. Even in very high INR, bleeding complications were uncommon. Problems at the point of collection are the major cause for discrepant INR results. Education of phlebotomists, doctors and nurses about the importance of proper collection technique will improve quality of INR result. Repeating INR is also crucial before instituting therapeutic measures.

Revalidation of CoaguChek XS plus system for INR monitoring in Taiwanese patients: effects of clinical and genetic factors.

In this study, we evaluated the performance of a point-of-care device, the CoaguChek XS Plus system, in the determination of prothrombin time and international normalized ratio (INR) based on ISO17593: 2007 criteria in Taiwanese patients. The underlying clinical and genetic factors were also investigated. Fifty patients receiving warfarin therapy were enrolled in this study. The accuracy of the CoaguChek XS Plus system was evaluated with linear regression analysis and bias plot by comparing with the data measured using Sysmex CA-1500. The clinical and genetic factors that may have caused a bias of ΃ 0.5 INR were evaluated with Fisher's exact test. From the 50 patients, 93 INR values were collected by each method. Linear regression analysis indicated a high correlation with r = 0.96, a slope of 1.05, and an intercept of - 0.14. Eight patients showed an INR bias ≥0.5 between the two methods. Only aspartate aminotransferase (AST) >34 U/L (3/8, 37.5% vs. 3/42, 7.1%; p = 0.044) and alanine aminotransferase (ALT) >36 U/L (3/8, 37.5% vs. 3/42, 7.1%; p = 0.044) were significantly different from each other. No differences were observed for hypoalbuminemia, elevated creatinine, anemia, and the polymorphisms of VKORC1 and CYP2C9. The CoaguChek XS Plus system presented results that were comparable with those obtained using laboratory CA-1500 method. Both methods fell within INR in the range of 2-4.5 defined by ISO17593:2007 and the clinically recognized therapeutic INR range of 2-3.5. Elevated AST and ALT levels might have interfered with the INR results.

Over‐Anticoagulation in Elderly Warfarinised Patients

ABSTRACTAimTo identify factors that contribute to over‐anticoagulation in elderly warfarinised patients and to review the management of over‐anticoagulation.MethodA prospective cohort audit was conducted over 6 months (1 February to 31 July 2011) at a teaching hospital. Inpatients with an international normalised ratio (INR) &gt; 4 were identified via a daily automated pathology screening report. Medical notes and drug charts of eligible patients were reviewed and data (medical history, drug history, warfarin regimen, INR results, clinical events, management of over‐anticoagulation) were compiled.Results62 patients prescribed warfarin were identified as experiencing over‐anticoagulation. 32 (52%) patients had INRs &gt; 4 and 12/32 (38%) patients had documented bleeding of clinical significance. Most patients had 2, 3 or 4 risk factors for over‐anticoagulation. Prevalent risk factors were: age &gt; 65 years (92%), co‐prescribing warfarin with interacting medications (76%) and renal insufficiency (21%). Co‐prescribed medications that interact or potentiate the effects of warfarin included antibiotics (47%) and non‐steroidal anti‐inflammatory drugs (21%). Most patients with INRs &gt; 4 were managed by withholding warfarin and administering a small dose of vitamin K.ConclusionWarfarin over‐anticoagulation was prevalent among elderly patients and those prescribed interacting medications. A conservative approach to the management of over‐anticoagulation was appropriate for most cases.

Telephone-based anticoagulation management in the homebound setting: a retrospective observational study

BackgroundAnticoagulation 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.MethodsThis 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.ResultsThe 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.ConclusionTelephone-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.

Point-of-care derived INR does not reliably detect significant coagulopathy following Australian snakebite

Point-of-care international normalised ratio (INR) has been suggested as a way to screen for venom-induced consumption coagulopathy following snakebite, but has not been validated for this. This study aimed to assess the diagnostic reliability of point-of-care INR for venom-induced consumption coagulopathy. This was a prospective study of snakebite patients recruited between January 2011 and May 2012 where a point-of-care INR was done and compared to an INR done on a laboratory coagulation analyser, as part of a quality assurance exercise. Data was obtained for each patient, including demographics, information on the snake bite, the point-of-care INR results and any laboratory derived coagulation studies. Snake identification was confirmed by expert identification or venom specific enzyme immunoassay. There were 15 patients with a median age of 29 years (2 to 68 y) and 13 were male. Four of the 7 patients with venom-induced consumption coagulopathy had an abnormal point-of-care INR (3 false negatives) and 1 of the 7 non-envenomed patients had an abnormal point-of-care INR (1 false positive). The patient with a falsely elevated point-of-care INR was given antivenom prior to formal coagulation studies. The point-of-care INR was also negative in the patient with an anticoagulant coagulopathy. The study shows that point-of-care INR testing devices should not be used in suspected snakebite cases in Australia to diagnose venom-induced consumption coagulopathy.

Point-of-care testing in snakebite: An envenomed case with false negative coagulation studies

Early detection of venom-induced consumption coagulopathy (VICC) in Australian snake bite is important for early antivenom administration.1 However, many patients present to smaller or rural hospitals where on-site laboratory coagulations studies are not available. Point-of-care (POC) devices for an international normalised ratio (INR) and d-dimer have become available and have been used in this setting. A 43-year-old woman presented to a small rural hospital in southwest Western Australia an hour after being bitten while putting her hand in a fish pond. She immediately saw ‘blood on her knuckle’, felt unwell with nausea and vomited twice, experienced chest tightness and felt faint. She did not apply first aid and washed the bite site. She was well on arrival to hospital, with no bleeding, no ptosis and normal vital signs. An INR was performed with a POC device (AlereTM INRatio2, Alere San Diego, San Diego, CA, USA), which was 1.3 on admission and 1.5 half an hour later. A pressure bandage was applied and she was transferred to a regional base hospital. On arrival at the base hospital 4 h post-bite the patient felt better and the INR was 0.9 on a second POC device (RocheTM CoaguChek, Roche Diagnostics, Mannheim, Germany). Blood collected at the same time was sent to the on-site laboratory where the INR was unrecordable. On examination there was oozing from the venipuncture site and no neurotoxicity. A snake venom detection kit was positive for tiger snake venom on urine. Two vials of tiger snake antivenom were given and the patient enrolled in the Australian Snakebite Project (ASP) randomised controlled trial of fresh frozen plasma (FFP).2 The patient was randomised to receive 4 units of FFP given immediately after antivenom. Additional serum and citrate samples were collected for ASP. A d-dimer performed on a POC device (RocheTM Cobas H232, Roche Diagnostics Limited, Rotkreuz, Switzerland) was 0.38 mg/L (<0.36). The patient had no immediate adverse reaction to antivenom or FFP and had an uneventful recovery, being discharged on day 3. Serial INR results are shown in Figure 1. Serial d-dimers done on the POC device ranged from 0.24 to 0.73 mg/L. The creatine kinase peaked at 432 IU/L. On follow up, the patient had symptoms consistent with mild serum sickness. Time-course of the laboratory compared with the international normalised ratio (INR) derived from the point-of-care (POC) testing devices. (), Laboratory INR; (), POC INR. Tiger snake venom (Notechis spp.) was detected at a concentration of 5.1 ng/mL in serum prior to antivenom and was undetectable post-antivenom. Repeat coagulation studies on admission gave an INR >12, activated partial thromboplastin time (aPTT) >180 s, undetectable fibrinogen and a d-dimer of 812 mg/L (<0.25). At 9 h post-bite, the INR was 2.2, aPTT was 39.5 s, fibrinogen was 0.4 g/L and d-dimer was 458 mg/L. The POC testing results for the INR and d-dimer were incorrect and misleading in this patient with tiger snake envenoming. This might have resulted in delayed treatment if the patient had not been transferred to a hospital equipped for laboratory confirmation of the INR. In addition to identifying problems with POC testing in VICC, the case underlines the importance of the history of a suspected snake bite and early systemic symptoms in the patient. Misleading POC INR results have been reported previously with laboratory-confirmed severe VICC.3, 4 This suggests that POC testing for INR and D-dimer are likely to be unreliable in VICC and formal laboratory testing is recommended until POC testing devices are formally assessed in VICC. Patients with suspected snakebite should be managed in hospitals with laboratory-based INR and aPTT testing available, or be transferred to a larger hospital. It remains unclear whether this problem applies to all POC testing systems. Currently, no other bedside clotting test is available, including the 20 min whole blood clotting test, which has also been shown to be unreliable,5 and glass tubes are not readily available in Australia. There is an urgent need for a rapid bedside clotting test for VICC. The study was supported in part by a National Health and Medical Research Council (NHMRC) Project Grant (ID490305). GKI is supported by a NHMRC Clinical Career Development Award (ID605817). None declared.

Administration tri-hebdomadaire de la warfarine en hémodialyse chronique. Résultats chez 12 patients

We report our experience of thrice-weekly warfarin administration, at the end of the dialysis session, in 12 patients (average age: 79±5years). In 10 cases, indication for anticoagulation therapy was atrial fibrillation, in one case a mechanical heart valve, in another case axillo femoral bypass. The International Normalized Ratio (INR) therapeutic goal was between 2 and 3, except for the patient with a mechanical aortic heart valve, whose goal was between 2.5 and 3.5. The INR was determined during the first dialysis session of the week. The thrice-weekly warfarin dose was based on this result. INR stability was assessed for each patient over an uninterrupted period of treatment of at least 6months. The average duration of warfarin treatment was 20±5months. One in two patients had hypertensive nephropathy. The average Charlson co-morbidity score was 9±1. Four patients were also taking aspirin or clopidogrel. The 10 patients with atrial fibrillation had an average CHA2DS2-VASc score of 4.4±0.8. The average haemorrage risk HAS-BLED score was 3.3±0.6. The average weekly warfarin dose was 23±5mg. No thrombotic events were observed. The side effects of warfarin were minor in most cases: (1) INR more than 6 in two cases without associated bleeding; (2) minor bleeding (nose, bladder) in three cases. One case of skin necrosis was observed. No cases of major bleeding (requiring blood transfusion) were observed. Only one patient was admitted into hospital as a result of warfarin treatment (the case of skin necrosis). Five hundred and forty-seven INR results were analyzed: 65% of these results were within the therapeutic goal, only 3% were either beneath 1.5 or over 4. To conclude, warfarin administration at the end of the dialysis session is efficient and associated with remarkable INR stability in the goal. It enables precise dose adaptation and optimum therapeutic observance, which in turn reduces the risk of bleeding.

Prevalencia de la fibrilación auricular desconocida y la no tratada con anticoagulantes. Estudio AFABE

Introduction and objectivesAtrial fibrillation constitutes a serious public health problem because it can lead to complications. Thus, the management of this arrhythmia must include not only its treatment, but antithrombotic therapy as well. The main goal is to determine the proportion of cases of undiagnosed atrial fibrillation and the proportion of patients not being treated with oral anticoagulants. MethodsA multicenter, population-based, retrospective, cross-sectional, observational study. In all, 1043 participants over 60 years of age were randomly selected to undergo an electrocardiogram in a prearranged appointment. Demographic data, CHA2DS2-VASc and HAS-BLED scores, international normalized ratio results, and reasons for not receiving oral anticoagulant therapy were recorded. ResultsThe overall prevalence of atrial fibrillation was 10.9% (95% confidence interval, 9.1%-12.8%), 20.1% of which had not been diagnosed previously. In the group with known atrial fibrillation, 23.5% of those with CHA2DS2-VASc≥2 were not receiving oral anticoagulant therapy, and 47.9% had a HAS-BLED score≥3. The odds ratio for not being treated with oral anticoagulation was 2.04 (95% confidence interval, 1.11-3.77) for women, 1.10 (95% confidence interval, 1.05-1.15) for more advanced age at diagnosis, and 8.61 (95% confidence interval 2.38-31.0) for a CHA2DS2-VASc score<2. Cognitive impairment (15.2%) was the main reason for not receiving oral anticoagulant therapy. ConclusionsThe prevalence of previously undiagnosed atrial fibrillation in individuals over 60 years of age is 20.1%, and 23.5% of those who have been diagnosed receive no treatment with oral anticoagulants.Full English text available from:www.revespcardiol.org/en

Prevalence of Undiagnosed Atrial Fibrillation and of That Not Being Treated With Anticoagulant Drugs: the AFABE Study

Introduction and objectivesAtrial fibrillation constitutes a serious public health problem because it can lead to complications. Thus, the management of this arrhythmia must include not only its treatment, but antithrombotic therapy as well. The main goal is to determine the proportion of cases of undiagnosed atrial fibrillation and the proportion of patients not being treated with oral anticoagulants. MethodsA multicenter, population-based, retrospective, cross-sectional, observational study. In all, 1043 participants over 60 years of age were randomly selected to undergo an electrocardiogram in a prearranged appointment. Demographic data, CHA2DS2-VASc and HAS-BLED scores, international normalized ratio results, and reasons for not receiving oral anticoagulant therapy were recorded. ResultsThe overall prevalence of atrial fibrillation was 10.9% (95% confidence interval, 9.1%-12.8%), 20.1% of which had not been diagnosed previously. In the group with known atrial fibrillation, 23.5% of those with CHA2DS2-VASc≥2 were not receiving oral anticoagulant therapy, and 47.9% had a HAS-BLED score≥3. The odds ratio for not being treated with oral anticoagulation was 2.04 (95% confidence interval, 1.11-3.77) for women, 1.10 (95% confidence interval, 1.05-1.15) for more advanced age at diagnosis, and 8.61 (95% confidence interval 2.38-31.0) for a CHA2DS2-VASc score<2. Cognitive impairment (15.2%) was the main reason for not receiving oral anticoagulant therapy. ConclusionsThe prevalence of previously undiagnosed atrial fibrillation in individuals over 60 years of age is 20.1%, and 23.5% of those who have been diagnosed receive no treatment with oral anticoagulants.

CPC-048 Establishing the Role of the Pharmacist in an Inpatient Anticoagulation Management Service in Belgium

BackgroundThe complexity of the management of vitamin K antagonist (VKA) treatment has led to the development in many countries of anticoagulant management services (AMS) which provide patient education and good...