Acceptability of CoaguChek S and CoaguChek XS generated international normalised ratios against a laboratory standard in a paediatric setting

Performance evaluation of coaguchek pro II in comparison with coaguchek XS plus and sta-r Max using a sta-neoplastine CI plus

INTRODUCTION

We evaluated the analytical performance of CoaguChek Pro II (Roche Diagnostics GmbH, Mannheim, Germany), a new point-of-care device measuring the international normalized ratio (INR) values, in comparison with CoaguChek XS Plus (Roche Diagnostics GmbH) and STA-R Max using STA-Neoplastine CI Plus (Diagnostica Stago SAS, Asnières-sur-Seine, France).

METHODS

The precision of Pro II was analyzed, according to the Clinical and Laboratory Standards Institute guidelines (CLSI POCT14-A2 and EP15-A3). In 105 clinical samples, the Pro II INR values were compared with those of XS Plus and STA-R Max using STA-Neoplastine CI Plus (CLSI EP09-A3 and EP35). We also compared the Pro II INR values between capillary blood (CB) and venous blood (VB; CLSI EP35).

RESULTS

The precision of Pro II was acceptable (within-run and between-run CV%: 2.71% and 3.28% at normal level; 1.52% and 4.47% at abnormal level, respectively). The Pro II INR values showed very high correlation and almost perfect agreement with those of XS Plus and STA-R Max using STA-Neoplastine CI Plus (r = .97 and κ = .94; r = .95 and κ = .91). The mean difference between Pro II and STA-R Max using STA-Neoplastine CI Plus increased as INR values increased, with 60% of samples showing differences >0.5 in the supratherapeutic range. The Pro II INR values showed very high correlation between CB and VB (r = .98).

CONCLUSION

Pro II INR values are accurate and reliable using both CB and VB; however, they should be confirmed by laboratory analyzers in the supratherapeutic range.

Use of a capillary specimen in the laboratory to verify a point-of-care international normalized ratio: Avoidance of a venipuncture in a pediatric setting

INTRODUCTION

Point-of-care (POC) international normalized ratio (INR) values above an institutional cutoff are confirmed in the laboratory using a gold standard venous specimen. This can be problematic in a pediatric setting.

METHOD

In this study, 449 consecutive POC INR results were compared to an INR performed in the laboratory on a capillary citrate specimen collected from the same finger-stick. The results were statistically analyzed.

RESULTS

The mean INR values from the CoaguChek XS and laboratory were 2.85 ± 1.19 and 2.63 ± 1.11, respectively. There was a good correlation between the methods with r = 0.97. Bland-Altman analysis indicated a bias of 0.22 favoring the CoaguChek XS, with 95% limits of agreement -0.29 to 0.72. Passing and Bablok method comparison resulted in a slope of 0.91 (y = 0.91x + 0.02). An INR of ≤0.5 was found between the methods in 89% of cases and 84% agreement was noted (κ = 0.69).

CONCLUSION

Comparing the capillary INR laboratory results to studies involving a venous specimen, the capillary specimen performed with equivalence. Thus, a capillary citrate specimen can be collected from the same finger-stick used to perform the POC INR for confirmation in the laboratory. This avoids the trauma of a venous collection in such a situation.

Verification of the qLabs international normalized ratio point-of-care device for monitoring of patients attending an anticoagulation clinic

INTRODUCTION

In the developing world, point-of-care (POC) testing for international normalized ratio (INR) plays an important role in the monitoring of patients on long-term warfarin therapy with limited access to healthcare ensuring safe and effective anticoagulation. A newly developed POC device for INR measurement by healthcare workers is the handheld qLabs POC device^® (Micropoint Biotechnologies Incorporated, Guangdong, China).

METHODS

The qLabs POC device^® was evaluated in 262 patients attending an anticoagulation clinic with regards to accuracy and precision of the INR results. The results were compared to the results obtained on the Stago STA R Max^® coagulation analyzer (Stago Diagnostica, Paris, France) on a wide range of normal and abnormal results of clinical relevance.

RESULTS

The mean laboratory INR (2.50 ± 1.08) was significantly higher than the qLabs POC device^® INR (2.38 ± 1.07) (P < .0001). The correlation coefficient (r) was .88, the slope coefficient was 1.0 (CI, 0.8-1.2), and the intercept was -0.10 (CI, -0.50 to 0.30). The mean of the differences was -0.13% (CI, -0.19 to -0.06). Dosage concordance was 85.46% and clinical agreement was 92.37%. However, clinical agreement was 42.42% in the subgroup above the target range (>3.5). The imprecision was within acceptable limits (<5%) and the error message rate was 4.38%.

CONCLUSION

In conclusion, the qLabs POC device^® is accurate and precise with high levels of dosage concordance and clinical agreement for INR values within and below the target range.

Self-testing and self-management of oral anticoagulation therapy in children

Children and adolescents on oral anticoagulation therapy (OAT) present special challenges in terms of rapid fluctuations in International Normalised Ratio (INR) values, interruption in daily life due to frequent hospital/doctor visits, and difficulties and pain in the performance of venepuncture. Optimised management of OAT improves the quality of treatment, potentially accomplished by new methods such as patient self-testing (PST) and patient self-management (PSM). A review was performed, identifying 11 trials with children and adolescents. All studies had different methodological problems, predominantly by being non-randomised trials. A total of 284 patients were included with a mean follow-up of 22 months, finding a time within therapeutic INR target range between 63% and 84%. The coagulometers used for estimating the INR values were found to have sufficient precision and accuracy for clinical use, but external quality control is probably advisable. It can be concluded that PST and PSM are at least as good treatment options as conventional management in highly selected children. Larger studies, preferably randomised, controlled trials using clinical endpoints, are obviously needed in order to elucidate whether these new regimens of treatment are superior to conventional management of oral anticoagulation therapy.

An evaluation of a coagulation system (Xprecia Stride) for utilisation in anticoagulation management

AIM

To evaluate the reliability and performance of the Xprecia Stride coagulometer under the conditions in which it is most likely to be used.

METHODS

The performance of the Xprecia Stride coagulometer was compared with a local laboratory and the CoaguChek systems routinely used for international normalised ratio (INR) estimation within one primary and one secondary care based anticoagulation clinic in Birmingham. Anticoagulation clinic personnel were trained to use the Xprecia Stride. Patients attending the clinics were eligible if aged ≥18 years and had received warfarin for at least 3 months. Consenting participants provided capillary blood samples for parallel testing on the Xprecia Stride and CoaguChek systems. At the secondary care clinic, a venous blood sample was also collected for laboratory INR estimation. INR results were compared using linear regression analysis and Bland-Altman plots.

RESULTS

A total of 102 laboratory and 205 parallel coagulometer INR tests were performed. Linear regression revealed strong correlation between the Xprecia Stride and the laboratory (r=0.83) and between the Xprecia Stride and CoaguChek systems (r=0.92). Within the therapeutic range, agreement between the systems was very good with 87% of the Xprecia Stride and laboratory INR results and 93% of the Xprecia Stride and CoaguChek INR results being within 0.5 INR units of each other.

CONCLUSION

INRs tested using the Xprecia Stride system showed good agreement with the laboratory and CoaguChek systems. Findings indicate that in the hands of the intended users the Xprecia Stride is accurate, reliable and acceptable for use in a routine clinical setting.

The clinical effectiveness and cost-effectiveness of point-of-care tests (CoaguChek system, INRatio2 PT/INR monitor and ProTime Microcoagulation system) for the self-monitoring of the coagulation status of people receiving long-term vitamin K antagonist therapy, compared with standard UK practice: systematic review and economic evaluation

BACKGROUND

Self-monitoring (self-testing and self-management) could be a valid option for oral anticoagulation therapy monitoring in the NHS, but current evidence on its clinical effectiveness or cost-effectiveness is limited.

OBJECTIVES

We investigated the clinical effectiveness and cost-effectiveness of point-of-care coagulometers for the self-monitoring of coagulation status in people receiving long-term vitamin K antagonist therapy, compared with standard clinic monitoring.

DATA SOURCES

We searched major electronic databases (e.g. MEDLINE, MEDLINE In Process & Other Non-Indexed Citations, EMBASE, Bioscience Information Service, Science Citation Index and Cochrane Central Register of Controlled Trials) from 2007 to May 2013. Reports published before 2007 were identified from the existing Cochrane review (major databases searched from inception to 2007). The economic model parameters were derived from the clinical effectiveness review, other relevant reviews, routine sources of cost data and clinical experts' advice.

REVIEW METHODS

We assessed randomised controlled trials (RCTs) evaluating self-monitoring in people with atrial fibrillation or heart valve disease requiring long-term anticoagulation therapy. CoaguChek(®) XS and S models (Roche Diagnostics, Basel, Switzerland), INRatio2(®) PT/INR monitor (Alere Inc., San Diego, CA USA), and ProTime Microcoagulation system(®) (International Technidyne Corporation, Nexus Dx, Edison, NJ, USA) coagulometers were compared with standard monitoring. Where possible, we combined data from included trials using standard inverse variance methods. Risk of bias assessment was performed using the Cochrane risk of bias tool. A de novo economic model was developed to assess the cost-effectiveness over a 10-year period.

RESULTS

We identified 26 RCTs (published in 45 papers) with a total of 8763 participants. CoaguChek was used in 85% of the trials. Primary analyses were based on data from 21 out of 26 trials. Only four trials were at low risk of bias. Major clinical events: self-monitoring was significantly better than standard monitoring in preventing thromboembolic events [relative risk (RR) 0.58, 95% confidence interval (CI) 0.40 to 0.84; p = 0.004]. In people with artificial heart valves (AHVs), self-monitoring almost halved the risk of thromboembolic events (RR 0.56, 95% CI 0.38 to 0.82; p = 0.003) and all-cause mortality (RR 0.54, 95% CI 0.32 to 0.92; p = 0.02). There was greater reduction in thromboembolic events and all-cause mortality through self-management but not through self-testing. Intermediate outcomes: self-testing, but not self-management, showed a modest but significantly higher percentage of time in therapeutic range, compared with standard care (weighted mean difference 4.44, 95% CI 1.71 to 7.18; p = 0.02). Patient-reported outcomes: improvements in patients' quality of life related to self-monitoring were observed in six out of nine trials. High preference rates were reported for self-monitoring (77% to 98% in four trials). Net health and social care costs over 10 years were £7295 (self-monitoring with INRatio2); £7324 (standard care monitoring); £7333 (self-monitoring with CoaguChek XS) and £8609 (self-monitoring with ProTime). The estimated quality-adjusted life-year (QALY) gain associated with self-monitoring was 0.03. Self-monitoring with INRatio2 or CoaguChek XS was found to have ≈ 80% chance of being cost-effective, compared with standard monitoring at a willingness-to-pay threshold of £20,000 per QALY gained.

CONCLUSIONS

Compared with standard monitoring, self-monitoring appears to be safe and effective, especially for people with AHVs. Self-monitoring, and in particular self-management, of anticoagulation status appeared cost-effective when pooled estimates of clinical effectiveness were applied. However, if self-monitoring does not result in significant reductions in thromboembolic events, it is unlikely to be cost-effective, based on a comparison of annual monitoring costs alone. Trials investigating the longer-term outcomes of self-management are needed, as well as direct comparisons of the various point-of-care coagulometers.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013004944.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Analytical performance of a point-of-care device in monitoring patients on oral anticoagulation with vitamin K antagonists

BACKGROUND

[Please check the following sentence for clarity: "Point-of-care devices measuring international normalized ratio have clinical appeal, reports of 'off-label' in-hospital/primary care use report improved time to intervention/dose adjustment."]Point-of-care devices measuring international normalized ratio have clinical appeal, reports of 'off-label' in-hospital/primary care use report improved time to intervention/dose adjustment. We evaluated the accuracy and precision of a device for such multiple patient use compared to a reference laboratory.

METHODS

The point-of-care international normalized ratio result of patients on oral anticoagulation at the Vascular Surgery clinic was compared to the reference to check for statistical and clinical correlation. This was a prospective case-control study design with sample size calculated for sensitivity of 87.5%, precision 5% and desired confidence level 95%.

RESULTS

There were 168 patients tested; 55% were male, the mean age was 45.4. Sixty per cent were in the target international normalized ratio range. Tests were done for statistical and clinical correlation. The international normalized ratio range using the point-of-care device was 0.8-7.5 (reference lab 0.8-10), mean international normalized ratio was 2.22 ± 1.6 (point-of-care device) compared to 2.46 ± 1.3 (reference lab). The mean absolute difference was 0.79 ± 0.92 and the mean relative difference was 8.1% ± 1.03. Data was analysed using a Bland-Altman plot yielding a mean of 0.738 (standard deviation 0.92). Concordance between the tests was 75% with r2 = 0.52 on linear regression. Using an error grid plot, excellent clinical correlation was seen in 63.8%. In 5.4% major corrective action was needed but potentially missed if relying on the point-of-care device.

CONCLUSION

The accuracy and precision of this point-of-care device is moderate. It may have potential utility only where access to a reference lab is difficult.

Assessment of point-of-care measurement of international normalised ratio using the CoaguChek XS Plus system in the setting of acute ischaemic stroke

BACKGROUND AND AIMS

Thrombolysis with alteplase (recombinant tissue plasminogen activator) is accepted hyperacute therapy for acute ischaemic stroke. Clotting must be normal before this can be administered safely. Laboratory testing of international normalised ratio (INR) takes 30-60 min, which can significantly delay administration of recombinant tissue plasminogen activator. Previous studies have suggested that point-of-care testing is useful in patients presenting with stroke and improves door-to-needle time. We performed a prospective study of point-of-care testing in patients presenting with acute ischaemic stroke.

METHODS

Fifty patients were entered into the study to compare point-of-care testing using the CoaguChek XS system with laboratory testing of INR.

RESULTS

Point-of-care testing correlated well with laboratory levels (R = 0.93, P < 0.0001). The standard deviation of difference between the two was 0.115. Overall, point-of-care testing tended to underestimate INR slightly, meaning that an INR value of 1.1 or less was required to be 95% certain that the laboratory value was 1.3 or below. Simultaneous testing using blood from a syringe was more consistent with laboratory results than testing capillary blood through finger prick.

CONCLUSION

Point-of-care INR testing correlates well with laboratory values. The results in this study mostly relate to values in the normal range. We suggest that it can be used to try to shorten door-to-needle time.

Comparison between the conventional method and a portable device for determination of INR

CONTEXT: Anticoagulation with warfarin is considered the appropriate treatment for venous thromboembolism and other thrombotic pathologies. Regular INR control is required for dosage adjustment and therapeutic control. Use of portable monitoring systems optimizes management of these patients. OBJECTIVE: To compare INR measurements taken using the portable Coaguchek XS system in capillary blood with the standard laboratory method using venous blood. METHOD: Fifty-two samples each of venous and capillary blood were collected from nineteen patients on warfarin, who had been admitted to the Hospital da Beneficência Portuguesa de São Paulo, and analyzed using the conventional method and the Coaguchek XS system, respectively. RESULTS: Spearman's correlation coefficient ® for the overall performance of the two methods was 0.978 (p<0.0001; 95%CI 0.961-0.988). The Kappa measure of agreement for all patients was 76.8% (p<0.001; IC: 95% 0.975-0.561). Mean INR according to the Coaguchek XS system underestimated the values provided by the conventional method by -0.01 INR points, with a standard error of 0.342. Results for INR values greater than 3.5 were satisfactory with a correlation coefficient of 0.71, but without statistical significance (p>0.714). CONCLUSIONS: The Coaguchek XS system can be used to monitor prothrombin time in patients on oral anticoagulants, provided INR values greater than 3.5 are confirmed using the conventional laboratory method.

[Evaluation of an educational program for oral anticoagulation in children with the INR home-monitoring CoaguChek XS(®)]

OBJECTIVE

To assesses the results of our education program relative to anticoagulation therapy and self-monitoring of INR.

MATERIALS AND METHODS

All children treated with oral anticoagulation therapy and followed using INR self-monitoring in Tours and Nantes, France, were included. A questionnaire on the treatment and its management was sent to the patients and their family. We analyzed the quality of anticoagulation using the proportion of INR within the target range.

RESULTS

Thirty-three children were included, with a mean age of 10.9years. Thirty-one questionnaires could be analyzed. Insufficient knowledge on the treatment objective and risks, the INR target range, and the interpretation of the INR was observed. We found 65.8% of INRs within the target range. The proportion of INRs within the target range was better with the INR self-testing than with the laboratory test (69.7% vs. 49.1%, P=0.003). There was no major complication observed during the study period. A moderate correlation (K=0.57) was noted between the INRs measured with the point-of-care monitor and the laboratory test on the same day.

CONCLUSION

However, home-monitoring of oral anticoagulation therapy increases the quality of anticoagulation. Both education and the training program need improvement in order to provide patients and their families with better knowledge on anticoagulation therapy.

Precision and accuracy of point-of-care testing coagulometers used for self-testing and self-management of oral anticoagulation therapy

BACKGROUND

Oral anticoagulation therapy is monitored by the use of the International Normalized Ratio (INR). Patients who perform self-testing or self-management use a point-of-care testing (POCT) coagulometer (INR monitor) to estimate their INRs. A precondition for a correct dosage of coumarins is a correct INR estimation, and the method and apparatus used for providing the INR measurements are crucial in this context. Several studies have been published regarding the precision and accuracy of these POCT coagulometers, and have led to diverse conclusions. It is difficult and challenging to perform an overview of the literature, owing to the vast amount of papers, with differences in design, statistical analysis, etc.

OBJECTIVES

The aim of this systematic review was to analyze the current literature, especially regarding the precision and accuracy of the POCT coagulometers, to provide recommendations for clinical use and quality control, and to point out areas for future research.

METHODS

We included a total of 22 studies, of which four were characterized as high-quality studies.

RESULTS

The precision of the POCT coagulometers was generally adequate for clinical use. Their performance in terms of accuracy has to be viewed in the context of the inherent inaccuracies of INR measurements.

CONCLUSIONS

The accuracy of POCT coagulometers seems, in this respect, to be generally acceptable, and they can be used in a clinical setting.

[Portable coagulometer devices in the monitoring and control of oral anticoagulation therapy: a systematic review]

OBJECTIVE

To compare portable coagulometer devices and conventional coagulometers. The clinical validity will be estimated via anticoagulation control (maintenance of therapeutic range), patient satisfaction, thrombotic or haemorrhagic events and mortality. Analytical validity will be studied in quality control terms.

DESIGN

Systematic review.

DATA SOURCES

MEDLINE and EMBASE databases, CRD, Cochrane, EMEA, FDA, EuroScan and the ClinicalTrials.gov.

METHODS

Inclusion criteria were studied in patients on anticoagulation therapy who used portable coagulometer devices. In an additional undertaking, the comparison with lab references was looked for, in order to evaluate the effectiveness. The quality of selected studies was assessed according to CASPe check-list. As meta-analysis was not possible, a qualitative synthesis was made.

RESULTS

Four evaluation reports and 7 systematic reviews were selected (two of them with meta-analysis). After these, 22 original articles were included for this review and they had high or very high score for CASPe check-list (≥7/10). Almost all of the studies found very high correlations between portable coagulometer devices and conventional coagulometers (r>90), and clinical advantages such as lower incidence of thromboembolism events. Three systematic reviews showed a lower mortality index.

CONCLUSIONS

The analytical-validity related articles show that portable coagulometers have an equivalent effectiveness to conventional coagulometers. Studies that include patient-reported outcomes show that self-monitoring patients, by means of portable coagulometers, have better analytical measurement results and fewer rates of thromboembolic events. Survival was analysed in very few studies; nevertheless, all of these show lower mortality. Similarly, the minority of selected articles includes economic evaluations, although they suggest a better cost-effectiveness of portable coagulometers compared to the conventional mode.

Assessing agreement between point of care and pathology laboratory results for INR: experiences from the Point of Care Testing in General Practice Trial

AIMS

To assess the level of agreement between international normalised ratio (INR) results obtained from pathology laboratories and point of care testing (PoCT) devices used in a general practice setting.

METHODS

INR pathology results were collected from multiple pathology laboratories and CoaguChek S PoCT devices over a 6 month period. Agreement was assessed using both clinically relevant agreement and the Bland Altman method.

RESULTS

Analysis was based on 1664 dual measurements collected on 417 patients from 26 general practices across Australia. The percentage of dual measurements satisfying the expanded and narrow agreement criteria were 91% and 89%, respectively. The mean difference in results and the 95% limits of agreement depended on the average INR result: mean difference = -0.30 + 0.08 x average; 95% limits of agreement = -0.30 + 0.08 x average +/- 0.77.

CONCLUSIONS

The current study provides further evidence that PoCT is an acceptable alternative to pathology laboratory testing in a general practice setting. The Bland Altman method is a useful and flexible tool for assessing agreement. Limits of agreement should be reported in future method comparison studies to assist clinicians in patient management.

Use of error grid analysis to evaluate acceptability of a point of care prothrombin time meter

BACKGROUND

Statistical methods (linear regression, correlation analysis, etc.) are frequently employed in comparing methods in the central laboratory (CL). Assessing acceptability of point of care testing (POCT) equipment, however, is more difficult because statistically significant biases may not have an impact on clinical care. We showed how error grid (EG) analysis can be used to evaluate POCT PT INR with the CL.

MATERIALS AND METHODS

We compared results from 103 patients seen in an anti-coagulation clinic that were on Coumadin maintenance therapy using fingerstick samples for POCT (Roche CoaguChek XS and S) and citrated venous blood samples for CL (Stago STAR). To compare clinical acceptability of results we developed an EG with zones A, B, C and D.

RESULTS

Using 2nd order polynomial equation analysis, POCT results highly correlate with the CL for CoaguChek XS (R(2)=0. 955) and CoaguChek S (R(2)=0. 93), respectively but does not indicate if POCT results are clinically interchangeable with the CL. Using EG it is readily apparent which levels can be considered clinically identical to the CL despite analytical bias.

CONCLUSION

We have demonstrated the usefulness of EG in determining acceptability of POCT PT INR testing and how it can be used to determine cut-offs where differences in POCT results may impact clinical care.

Point-of-care INR measurement in children requiring warfarin: what has been evaluated and future directions

Many children are surviving primary illnesses and now require thromboprophylaxis as a result of advances in management. Vitamin K antagonists are commonly prescribed to prevent or treat thrombosis. These agents are far more challenging to effectively manage in children. As a result of these challenges, frequent blood monitoring to measure international normalized ratio (INR) values is required. Point-of-care (POC) INR monitors use a capillary blood sample that has been expressed as a solution to improve effective management of vitamin K antagonist therapy. POC INR meters have been demonstrated to be accurate and precise in measuring INRs. Implementation of a standardized education program prior to patient use of POC meters results in differences between measured laboratory INRs and POC INR comparisons that meet criteria for clinical relevance. This indicates that POC INR meters are safe and effective for use in children.