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

Evaluation of a whole blood point-of-care coagulation analyzer in dogs

OBJECTIVE

To compare the accuracy of a point-of-care coagulation analyzer (POCCA) with a reference laboratory coagulation analyzer (LabCA) and to evaluate for confounding factors that could alter the performance of the POCCA.

DESIGN

Prospective, observational study.

SETTING

Two university veterinary teaching hospitals.

ANIMALS

Forty-three client-owned dogs undergoing coagulation testing between April 2020 and June 2021.

METHODS

Samples were obtained from dogs undergoing coagulation testing as part of a diagnostic workup. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) were measured on the POCCA and on the LabCA. PCV, platelet count, total plasma protein, hyperbilirubinemia, hemolysis, lipemia, and autoagglutination were recorded.

RESULTS

Moderate correlation was seen for PT and strong correlation was seen for aPTT between the POCCA and the LabCA (PT: 0.59, P < 0.0001; aPTT: 0.71, P < 0.0001). The POCCA results were consistent with normal or hypocoagulable samples for 30 of 38 PT and 33 of 37 aPTT results, as identified by the LabCA. Samples with PCV of 30%-55% were moderately correlated (PT: 0.63, P = 0.0004; aPTT: 0.63, P = 0.0003), but those outside that range were more likely to register an error message on the POCCA or provide disparate results. When hemolysis was present, there was a weak correlation between the POCCA and the LabCA for PT (rho: 0.38 [95% confidence interval: 0.19-0.76], P = 0.18) and a strong correlation for aPTT (rho: 0.86 [95% confidence interval: 0.62-0.95], P < 0.0001). Samples with hyperbilirubinemia were strongly correlated for PT (0.97, P = 0.002) but not for aPTT. Lipemia and autoagglutination were not observed.

CONCLUSION

There was an acceptable correlation in patients with PCV within the manufacturer's recommended reference range; however, measurements on samples with PCV outside the reference range were inconsistent with the LabCA. Caution should be used when using the POCCA in patients with coagulopathy and anemia or other potential confounders.

Role of Multimodal Monitoring in the Management of Massive Blood Transfusion in Pediatric Patients Undergoing Excision of Choroid Plexus Carcinoma - A Case-Based Review of a Novel Perioperative Protocol

Choroid plexus carcinomas (CPCs) are rare intraventricular lesions encountered in the pediatric population. The dreaded perioperative complication causing high mortality and morbidity in patients undergoing excision of CPC is massive intraoperative hemorrhage, which results in massive blood transfusion, and coagulopathy. Hence, the main crux of perioperative management is to tackle intraoperative hemorrhage and coagulopathy by instituting goal-directed blood transfusion guided by multimodality monitoring. This case series and literature review aims to present our institutional experience wherein the patients had a favorable outcome post-excision of CPC owing to goal-directed blood transfusion protocol guided by multimodality monitoring in the perioperative period.

Comparison of Point-of-Care PT-INR by Hand-Held Device with Conventional PT-INR Testing in Anti-phospholipid Antibody Syndrome Patients on Oral Anticoagulation

Evidence on agreement of point-of-care (POC) INR testing with laboratory testing in APS patients on oral anticoagulation (OAC), is scarce. This study assessed agreement of paired PT INR testing by a POC device vs. conventional platform-based laboratory test, in APS patients on OAC using a pre-determined definition of agreement. Simultaneous paired PT INR estimation in 92 APS patients was carried out, during October 2020-September 2021. POC INR was performed on capillary blood (pin prick) using the qLabs® PT-INR hand-held device, while laboratory INR estimation was performed using citrated blood (venepuncture) on STA-R Max Analyzer® using STA-NeoPTimal thromboplastin reagent®. Concordance was defined no greater than ± 30% (as per international standards ISO 17593:2007 guidelines) for each paired INR estimation. Agreement between the two was defined as ≥ 90% of paired INR measurements being concordant. 211 paired estimations were performed, within which 190 (90%) were concordant. Good correlation was seen between the 2 methods of INR estimation on Bland Altman plot analysis with an Intra-class correlation coefficient (95% CI) of 0.91(0.882, 0.932). Lab INR range > 4 (P = 0.001) was a significant predictor of higher variability between both methods of INR estimation. Lupus anti-coagulant, other anti-phospholipid antibodies (APL) or triple APL positivity did not result in any statistically significant variation in paired measurements. This study demonstrated good correlation between POC INR measurement and Lab INR estimation and agreement was ascertained between the 2 methods in APS patients on OAC.

Improving anticoagulation in sub-Saharan Africa: What are the challenges and how can we overcome them?

Patients in sub-Saharan Africa generally have poor anticoagulation control. We review the potential reasons for this poor control, as well as the potential solutions. Challenges include the affordability and centralisation of anticoagulation care, problems with access to medicines and international normalised ratio monitoring, the lack of locally validated standardized dosing protocols, and low levels of anticoagulation knowledge among healthcare workers and patients. Increasing numbers of patients will need anticoagulation in the future because of the increasing burden of noncommunicable disease in the region. We propose that locally developed "warfarin care bundles" which address multiple anticoagulation challenges in combination may be the most appropriate solution in this setting currently.

The Genetics of Warfarin Dose-Response Variability in Africans: An Expert Perspective on Past, Present, and Future

Coumarins such as warfarin are prescribed for prevention and treatment of thromboembolic disorders. Warfarin remains the most widely prescribed and an anticoagulant of choice in Africa. Warfarin use is, however, limited by interindividual variability in pharmacokinetics and a narrow therapeutic index. The difference in patients' pharmacodynamic responses to warfarin has been attributed to genetic variation in warfarin metabolism and molecular targets (e.g., CYP2C9 and VKORC1) and host-environment interactions. This expert review offers a synthesis of human genetics studies in Africans with respect to pharmacogenetics-informed warfarin dosing. We identify areas that need future research attention or could benefit from harnessing existing pharmacogenetics knowledge toward rational and optimal therapeutics with warfarin in African patients. A literature search was conducted until January 2019. A total of 343 articles were retrieved from nine African countries: Botswana, Ethiopia, Egypt, Ghana, Kenya, South Africa, Sudan, Tanzania, and Mozambique. We found 19 studies on genetics of warfarin treatment specifically among Africans. Genes examined included CYP2C9, VKORC1, CYP4F2, APOE, CALU, GGCX, and EPHX1. CYP2C9*2 and *3 alleles were highly frequent among Egyptians, while rare in other African populations. CYP2C9*5, *8, *9, and *11, and VKORC1 Asp36Tyr genetic variants explained warfarin variability in Africans better, compared to CYP2C9*2 and *3. In Africa, there is limited pharmacogenetics data on warfarin. Therefore, future research and funding commitments should be prioritized to ensure safe and effective use of warfarin in Africa. Lessons learned in Africa from the science of pharmacogenetics would inform rational therapeutics in hematology, cardiology, and surgical specialties worldwide.

An introduction to point-of-care testing in extracorporeal circulation and LVADs

There is a delicate balance between bleeding and clotting in patients on circuits such as ventricular assist devices or extracorporeal membrane oxygenation. Traditional coagulation tests, prothrombin time, activated partial thromboplastin time, and anti-factor Xa levels, are used to monitor patients on these devices. However, turnaround times and inability to assess global hemostasis, including platelets and fibrinogen have contributed to a recognition that faster, accurate, and more informative coagulation tests are needed. Activated clotting time is used to monitor heparin in patients on circuits and has the advantages of being a near-patient point-of-care test. However, its utility is limited to heparin monitoring. Viscoelastic tests (thromboelastometry and thromboelastography) are global, whole-blood coagulation tests, and whole-blood platelet aggregometry evaluates platelet function. Ideally, these tests can ensure that patients are within the therapeutic range of their antithrombotic medications, identify patients at risk for hemorrhagic or thrombotic complications, and guide management of acute bleeding complications. This ideal is currently hampered by a lack of studies that delineate clear ranges that are clinically relevant. Future research is needed to better understand the optimal use of point-of-care coagulation testing in patients on extracorporeal circuits and ventricular assist devices.